Saskatoon berry (Amelanchier alnifolia): nutritional composition, phytochemical, health benefits, shelf-life extension and utilization

Abstract

Saskatoon berry (STB) contains various nutrients and phytochemicals. In recent years, considerable research has been conducted on the chemical composition and biological functions of the STB. STB encompass a diverse range of species with varying nutritional and functional profiles, which necessitates a systematic review to summarize and synthesize existing knowledge. In this review, we summarize the current developments in STB as a potential source of bioactive compounds. Special emphasis on health benefits, storage techniques, and applications. STB is a rich source of nutrients (carbohydrates, proteins, fats, and minerals) and phytochemicals (including polyphenols, polysaccharides, volatile, etc.) that are biologically active and beneficial to human health. These bioactive constituents have many health advantages, including antioxidant, anti-inflammatory, metabolic syndrome modulating, antimicrobial, and anticancer capabilities. In addition, practical applications of storage technology in STB are discussed. Recommendations for maximizing the potential of STB in promoting their development as functional food materials/ingredients are also offered.

Introduction

Saskatoon berry (Amelanchier alnifolia Nutt) belongs to the Rosaceae family, the Pomoide subfamily. Its aliases are Western Serviceberry, Western Shadbush, and Western Juneberry. It is native to North America, Europe, and Africa (Lavola et al., 2012) (Fig. 1A). There are 15 major varieties of Saskatoon berries (STB) with differences in physiological characteristics and nutrient content (Zhao et al., 2020a). STB begins to bear fruit after 3 to 5 years of planting, produces significant yields at 6 to 8 years, and reaches its maximum yield at 12 to 15 years. Its flowers are white and bloom from April to July. The fruit ripens from July to September as a small pome resembling blueberries. Unripe berries are white, then turn red, and finally become dark purple, indicating it ripen. A cluster contains 7–15 berries. Each fruit has a diameter of 14–18 mm and weight ranging from 0.9 to 1.4 g (Rop et al., 2013). The average production in mature orchards is 3000 to 4000 pounds per acre. The largest area of STB cultivation is in Canada. It is one of the most important commercial fruits in Canada and the second largest fruit grown in Saskatchewan. In 2022, STB’s total acreage in Canada was 1080 hectares, producing 689 metric tons, and the gross value of production was 2.915 million Canadian dollars (Horticulture Section Crops And Horticulture Division Agriculture And Agri-Food Canada, 2023). Ripe STB is usually consumed fresh or dried, and it can be used in drinks, syrups, fruit cakes, wine, and jams (Szpadzik And Krupa, 2021).

Fig. 1.

Global distribution (A), publication trends (B) and publication journal names (C) of Saskatoon berry

Over the past 20 years, the focus of STB research has been on chemical characterization and bioactivity analysis (Fig. 1B and C). STB has a rich nutritional value, and its bioactive components include polyphenols, polysaccharides, and flavonoids, which are effective antioxidants. STB has health-promoting effects, such as regulating intestinal flora, anti-inflammatory effects, and cholesterol reduction (Lachowicz et al., 2021). These phytochemicals enhance STB’s potential functions and can be used as ingredients in functional foods and pharmaceuticals to improve human health. STB contains all essential amino acids and nine non-essential amino acids (among them, cysteine, tyrosine, and arginine) (Master And Macedo, 2021). As a result, the demand for STB derivatives is likely to increase, providing an opportunity to develop STB in high-value products. This review summarizes the nutritional components, phytochemical, health benefits and storage techniques of STB. In addition, potential future applications of STB are discussed/ proposed.

Nutritional composition and bioactive phytochemicals of STB

Nutritional composition

Although STB is often regard as similar in shape and color to blueberries, it is a pome fruit that is more closely related to apple (Amicucci et al., 2019). STB consists of peel, flesh, and seed. Historically, Canadian aborigines used the STB juice to treat stomach problems, whereas unripe fruits were used as eye and eardrops (Nagalakshmi et al., 2014). Therefore, the study of nutrients and bioactive ingredients in STB is of scientific value in explaining the active ingredients that exert these effects and their mechanisms of action. STB is rich in carbohydrates (17.1–19.7 g/100 g), protein (1.23–1.44 g/100 g), ash (0.59–0.67 g/100 g), total fat (0.40–0.53 g/100 g), and minerals (0.25–0.48 g/100 g) (Mazza, 2005).

The importance of carbohydrates in nutrition is well known. Carbohydrates are structurally diverse and include monosaccharides, disaccharides, oligosaccharides, and polysaccharides (Amicucci et al., 2019). Carbohydrates are the main macrocomponent of STB, with an average value of 18.48 g/100 g, which is higher than that of blueberries (14.49 g/100 g). The average glucose, fructose, and sucrose contents were 6.38, 5.47, and 0.59 g/100 g, respectively. Another study demonstrated that the sugar content of STB ranged from 9.02 to 19.69 g/100 g and the pectin content ranged from 0.67% to 1.33% (Lachowicz et al., 2017). The total dietary fiber content of STB was 5.45–5.79 g/100 g, with soluble and insoluble fiber contents of 0.44–0.92 and 4.7–5.7 g/100 g, respectively (Mazza, 2005). STB has 1.7 times more dietary fiber than blueberries (3.50 g/100 g). The contents of total dietary fiber in STB range between blueberries and strawberries (15.50 g/100 g) (Miller et al., 2019; Ait Lhaj et al., 2021). Dietary fiber is vital for preventing disease (He et al., 2022). Different sources of dietary fiber have different physiological functions, such as reducing the risk of obesity (Delzenne et al., 2020), diabetes (Zhao et al., 2020b), cancer (He et al., 2019), and intestinal diseases (Beukema et al., 2020).

Plant proteins have become increasingly popular as useful components in human nutrition and commercial formulations in recent years. They are an economical and versatile alternative to animal source proteins (Sá et al., 2020). Previous research has demonstrated the importance of plant protein in human nutrition because of their ability to supply the body with essential amino acids (López et al., 2018). The protein content of STB is 1.23–1.44 g/100 g, which is higher than that of blueberries (0.40–0.74 g/100 g) (Correia et al., 2016). The study found that STB contains all essential amino acids and 9 non-essential amino acids, including three essential amino acids for preemies that are cysteine, tyrosine, and arginine. The highest content is glutamic acid (0.212 g/100 g), which is 2.3 times higher than that of blueberry. It is worth noting that STB contains three branched-chain amino acids (BCAAs), including isoleucine, leucine, and valine, all of which are higher than those in blueberries. BCAAs is the most important and effective nutritional supplements for any sport. They are very popular and commonly used by well-trained athletes (Master And Macedo, 2021). Therefore, STB is a good source of amino acids. However, studies on the functional properties of STB amino acids and their mechanisms of action are limited. In addition, the bioavailability of STB proteins has not yet been determined.

The total fat of STB is 0.40–0.53 mg/100 g. One hundred grams of STB seed oil contains 0.13 g of triglycerides and 99.32 g of total fatty acids. The STB is rich in unsaturated fatty acids, with the saturated fatty acids accounted for approximately 9.85 g/100 g of the total fatty acids, in comparison to the monounsaturated and polyunsaturated fatty acids that exist at significantly higher levels, with values of 31.29 and 68.16 g/100 g, respectively. The palmitic acid is the major unsaturated fatty acid of STB, with value of 6.62 g/100 g (Bakowska-Barczak et al., 2009). Blueberries comprise saturated fatty acids (7.24 g/100 g), monounsaturated fatty acids (21.21 g/100 g), and polyunsaturated fatty acids (43.41 g/100 g), all of which are lower than those of STB (Bederska et al., 2021). Another study showed that the fatty acid content of STB seed oil is 99.36 g/100 g. These studies showed that STB is a good source of fat. The excessive intake of saturated fatty acids has been associated with cardiovascular disease in humans, whereas reducing saturated fat intake has been reported to reduce the risk of cardiovascular disease by 17% (Hooper et al., 2020). The linoleic acid and α-linolenic acid contents of STB seed oil were 57.19 and 0.88 g/100 g, respectively (Bakowska-Barczak et al., 2007).

STB is a good source of micronutrients such as minerals and vitamins. The mineral content varies between varieties. Phosphorus (364.68–480.33 mg/kg), potassium (2746.05–4311.72 mg/kg), calcium (620.71–845.93 mg/kg), magnesium (210.09–315.92 mg/kg), and sodium (13.87–25.01 mg/kg) are the major mineral constituents of STB. Other minerals such as zinc, iron, copper, and manganese have also been reported (Rop et al., 2013). However, the bioavailability of these minerals remains to be studied. In addition, various vitamins have been found in STB (Fang, 2021). Vitamin A is the major vitamins with value of 10.68 mg/100 g, followed by Vitamin C (ascorbic acid) (3.55 mg/100 g), B2 (riboflavin) (3.54 mg/100 g), Vitamin E (α-tocopherol) (1.12 mg/100 g), B5 (pantothenic acid) (0.31 mg/100 g), B1 (thiamine) (0.04 mg/100 g), and B9 (4.55 µg/100 g). The factors affecting the accumulation of minerals and vitamins have not been studied.

Phytochemicals

STB contains various active compounds. Its main phytochemicals are polyphenols, volatile components, and sterols. Table 1 presents the distribution of major polyphenolic compounds across different anatomical regions of Saskatoon berry (fruits, pericarp, pulp, and seeds). This topic will be discussed in detail in the following section on polyphenols, whereas the volatilization components and other compounds will be addressed in subsequent sections.

Table 1.

Distribution of phytochemicals in different parts of Saskatoon berry

Parts	Anthocyanin (mg/100g.dm)	Flavanols (mg/100g.dm)	Phenolic acid (mg/100g.dm)
Whole fruit	571.2–1661.5	655.7–2353.5	196.6–1115.2
Peel	532.9–2083.0	1430–3849.9	215.9–1816.6
Flesh	7.2–209.7	609–1702.2	59.8–583.9
Seed	0.7–5.3	117.9–1847.4	5.6–90.7
References	Lachowicz et al. (2019a, b), Lachowicz et al. (2020a)

Polyphenols

Phenolic compounds are the main phytochemicals in STB, including flavonoids, phenolic acids, and proanthocyanidins (Marjanovic et al., 2021). The total phenolic content (TPC) significantly differed among the STB varieties. Nine varieties of STB (whole fruit) grown in the Czech Republic were reported to have TPC of 2.56–3.80 (g GAE/kg). The highest TPC among them was Tisnovsky, and the lowest was NS-2 (Rop et al., 2012). Scholars in Poland have also determined the TPC for different STB varieties. The study found that the TPC of the seven varieties ranged from 2992.35 to 6390.36 mg/100g.dm. The highest TPC was found in Clone Type S and the lowest in Pembina (Lachowicz et al., 2017). Souza et al. (2019) measured TPC in five Canadian varieties. The results showed that the highest TPC was found in Northline (50.42 mg/kg), followed by Martin (29.41 mg/kg) and Pembina (21.55 mg/kg). Another study indicated that TPC in the STB ranged from 1423.5 to 5130.5 (mg/kg d.m), the highest observed in Thessien and the lowest recorded in Pembina. The variation of TPC in different varieties of STB could be due to different genetic make-up and growing conditions such as climate and soli factors. Secondary metabolite synthesis and nutritional potential of edible and medicinal plants are significantly affected by these factors. In addition, comparison of TPC content in different parts of the fruit revels that the pericarp contains 40%–60% higher TPC than that of the flesh and seeds, suggesting that the polyphenols of STB are mainly distributed in the peel of the fruit. (Lachowicz et al., 2020a). These findings showed that the STB has a higher TPC than the other berry fruits such as wild raspberry (76.06 mg/kg), mulberry (33.15 mg/kg), black current (28.98 mg/kg), and blueberry (20.37 mg/kg) (Chen et al., 2014).

Phenolic acids are the most common polyphenols that consisted of aromatic phenols with carboxylic acid functional groups (Aleixandre et al., 2022). Previous research involving five different varieties of STB revealed that the phenolic acid of STB accounted for 11–27% of TFC. The phenolic acids of STB consisted of nine compounds, of which chlorogenic acid is the most abundant (358 mg/100g d.m) (Lachowicz et al., 2020a). In addition, other reports have indicated other phenolic acid compounds in STB, such as 3- and 5-feruloylquinic acid (Lachowicz et al., 2017). In vitro studies have shown that phenolic acids, anthocyanins, and proanthocyanidins in STB can lower blood glucose levels and significantly reduce the expression of interleukin-1β and cyclooxygenase-2. Moreover, the berry samples have been demonstrated to regulate lipid metabolism, ameliorating metabolic syndrome (Kraft et al., 2008).

Flavonoids are one of the important phytochemicals bioactive compounds of berry fruits. It consists of 15 carbon atoms and contains two benzene rings and a heterocycle. Substituting hydroxyl, methoxy, glycosidic, and other functional groups at different sites on the basic C6-C3-C6 skeleton results in a series of flavonoids of different types and isomers (Wang et al., 2022). Previous studies on several STB cultivars showed that the Tisnovsky variety had the highest flavonoid content (562.8 ± 20.0 mg/kg), followed by Smoked (550.5 ± 20.5 mg/kg) and Thiessen (531.2 ± 17.7 mg/kg) cultivars. In addition, quercetin was the second most abundant flavonoid in STB. The rutin content of Thiessen and Smoky were 23.6 and 30.7 mg/100 g, respectively, whereas the rutin concentration in Thiessen was twice than that in Martin (Juríková et al., 2013).

Anthocyanins are natural colorants found in most berries, giving them attractive red, purple, and black colors (Rambaran And Bowen-Forbes, 2020). Anthocyanins are the main pigments in STB. The color of the fruit peel and flesh intensified with the ripening of STB; when STB was ripe, the whole fruit was dark purple. Research has found that the total anthocyanin content in the ripe fruits ranged from 154 to 201 mg/100 g (Jin et al., 2015). The cyanidin-3-o-galactoside and cyanidin-3-o-glucoside are the two main components of the STB, with content accounting for 409.19 mg/100 g and 89.82 mg/100 g, respectively (Yang et al., 2016). Previous research has indicated that cyanidin-3-o-glucoside supplementation can modulate intestinal flora and metabolic disorders as well as reduce inflammation caused by a diet high in fat and sucrose (Huang et al., 2020).

Proanthocyanidins (PCA) are complexes consisting of monomeric, oligomeric, and polymeric flavan-3-ols linked through interfluve bonds (Chen et al., 2023). Kraft et al. (2008) identified a series of PCA polymers ranging from dimers to hexamers in STB. Moreover, the study found that PCA can ameliorate hyperglycemia in vivo in a rat model. Significant differences in the PCA content of STB have been reported in the literature. Lavola et al. (2012) reported that PCA levels in STB were 32–37 (mg/g), representing 46–69% of TPC. It consists of (-)-epicatechin units linked by β-type bonds. In a recent study, Marjanovic et al. (2021) founded that the total PAC content of STB was significantly lower, with a value of 1.057 (mg/g). The variations in the PCA levels could be due to differences in varieties, growth environments, storage conditions, and assay methods. Therefore, the development of stable detection techniques is one can be one of the focuses for future research.

Volatile compounds

A useful indicator for assessing the freshness, quality, and authenticity of berries is volatile molecules compounds (Dymerski et al., 2016). A previous study showed that there were 16 major volatiles in STB. Among them, benzaldehyde (85.5%), benzyl alcohol (2.5%), phenylacetaldehyde (0.9%), hexanal (0.5%), and 2-hexenal (0.2%) had an important organoleptic influence on fruit aroma (Parliment, 2001). The content of volatile components differs among different varieties. The STB varieties of Smoky and Thiessen had more aromatic substances and were more flavorful. This is attributed to their higher content of amygdalin and prunasin. The amygdalin and prunasin contents in ripe fruits were 42.00–129.20 g/kg and 5.01–13.71 g/kg, respectively. The amygdalin and prunasin contents in unripe fruits were 0–60.00 g/kg and 0–30.90 g/kg, respectively (Mazza And Cottrell, 2008). Following the chewing or processing, amygdalin or prunasin breaks down into benzaldehyde, hydrocyanic acid, and glucose Czech researchers have studied the volatile compounds of five local STB varieties. They identified 31 volatile compounds. Alcohols were mainly dominant, accounting for approximately 26.7%–46.7%, followed by aldehydes (20–34.8%), esters (12.5–26.7%), ketones (0.3–15.8%), acids (0–7.7%), and terpenoids (0–5.3%) (Butorová et al., 2016).

Other compounds

Other compounds such as carotenoids, cyanoglucosides, and sterols were also found in STB. Ripe STB fruits contained three carotenoids: lutein (0.29–0.85 mg/kg), zeaxanthin (0.05–0.12 mg/kg), and β-carotene (4.82–14.63 mg/kg). The green, unripe fruit had significantly higher levels of all three compounds than the ripe fruit. Lutein, zeaxanthin, and β-carotene of green fruit ranged between 4.82–14.63 mg/kg, 0.25–0.77 mg/kg, and 0.02–0.04 mg/kg, respectively. However, because these results were reported in a limited number of studies, the properties of these components need to be studied in depth. STB is rich in sterols, and its seed oil contains 7357–15,771 mg/kg of total sterols (Bakowska-Barczak et al., 2009). The sterol content of STB seed oils is higher than that of commercial seed oils, such as canola (4358–10,569 mg/kg), sunflower (2212–4146 mg/kg), and soybean (1735–4328 mg/kg) (Fine et al., 2016). Sterols have attracted attention owing to their ability to reduce triglycerides and cholesterol (Kopylov et al., 2021). In addition, sterols contribute to other biological activities, including anti-inflammatory (Ku And Lin, 2013), neuroprotective (Vanmierlo et al., 2015), and immunomodulatory (Alhazmi et al., 2021). However, research on STB sterol is limited; thus, it needs to be further explored.

Health benefits

STB has various biologically active components with various health benefits. In vitro and in vivo experiments were used to study the health benefits of STB whole fruit, fruit flesh, pericarp, seeds, leaves, and branches, mainly focusing on antioxidant, anti-inflammatory, regulation of metabolic syndrome, anticancer, neuroprotective, antidiabetic, and antimicrobial activities. The health benefits of STB are described in detail below (Fig. 2A).

Fig. 2.

The health benefits (A) and comprehensive application status (B) of Saskatoon berry

Antioxidant activity

Oxidative stress can lead to an excessive accumulation of free radicals in the body, which can cause various chronic diseases (Yang et al., 2023). Phenolics are common natural antioxidants that prevent oxidation, and STB extracts are of interest because of their excellent antioxidant properties. Studies on different parts of antioxidant extracts have shown that they exhibit good antioxidant activity. In addition, products prepared or fortified with STB exhibited significant antioxidant activity (Table 2).

Table 2.

Antioxidant activity and anti-inflammatory effects of different parts of Saskatoon berry

Parts	Sample	Results	References
Antioxidant activity
Whole fruit	Ethanol-formic acid–water extracts	Northline: (DPPH: 23.1 ± 1.3 mM TEAC/100mg, ABTS 327.5 ± 5.2 mM TEAC/100mg	Souza et al. (2019)
		Martin: (DPPH: 14.7 ± 1.7 mM TEAC/100mg, ABTS: 177.1 ± 4.4 mM TEAC/100mg)
Wet Pomace	Ethanol formic acid–water extracts (Northline)	DPPH: 19.4 ± 1.8 mM TEAC/100 mg, ABTS: 304.8 ± 7.1 mM TEAC/100 mg
Dry Pomace		DPPH: 16.8 ± 1.0 mM TEAC/100 mg, ABTS 327.8 ± 5.2 mM TEAC/100 mg
Whole fruit	Methanolic extracts	Total antioxidant activity: 4170 to 5290 mg Eq/kg. Inhibitory ability on nitric oxide (21.08% to 27.52%), superoxide anion (25.14% to 30.73%), hydroxyl radical (18.25% to 21.18%), and antioxidant activity in the liver lipid system (7.90% to 8.38%)
Whole fruit	Extracts (ethanol, water, acetic acid, 70:30:1, v/v/v)	Whole fruit extract: (DPPH: 90%, ORAC: 365.4 ± 21.5 mg TE/100 mL, TRAP: 124.1 ± 11.5 mg TE/100 mL)
Leaves		DPPH: 90%, ORAC: 1015.2 ± 29.7 mg TE/100 mL TRAP: 424.3 ± 33.2 (mg TE/100 mL)
Branches		DPPH: 90%, ORAC: 697.1 ± 33.8 mg TE/100 mL, TRAP: 24.1 ± 24.6 mg TE /100mL
Whole fruit	Powder	DPPH: 9.5–18.9 mmol TE/100 g; TRAP: 15.0–29.9 mmol TE/100 g	Lachowicz et al. (2020a)
Peel		DPPH: 32.3–57.9 mmol TE/100 g; TRAP: 14.5–41.5 mmol TE/100 g
Flesh		DPPH: 2.3–8.3 mmol TE/100 g; TRAP: 3.1–10.7 mmol TE/100 g
Seeds		DPPH: 0.2–3.6 mmol TE/100 g; TRAP: 0.4–5.7 mmol TE/100 g
Whole fruit	Bread enriched with STB powder	3% micro-encapsulated STB fruit powder: (antioxidant activity: 93%)	Lachowicz et al. (2021)
Whole fruit	Fruit beer	DPPH: Amela cultivar: 1.38 ± 0.08 mmol TE/L, Smoky cultivar: 1.68 ± 0.06 mmol TE/L, Martin cultivar: 1.58 ± 0.10 mmol TE/L ABTS: Amela cultivar: 1.65 ± 0.06 mmol TE/L, Smoky cultivar: 1.63 ± 0.10 mmol TE/L, Martin cultivar: 1.67 ± 0.07 mmol TE/L FRAP: Amela cultivar: 1.83 ± 0.04 mmol TE/L, Smoky cultivar: 2.46 ± 0.07 mmol TE/L, Martin cultivar: 1.81 ± 0.07 mmol TE/L	Gorzelany et al. (2022)
Whole fruit	Extracts	Cupric ion-reducing antioxidant capacity value of 323.99 µmol Trolox/g and ferric reducing antioxidant power value of 4.10 μmol Fe2+/g	Dăescu et al. (2024)
Anti-inflammatory effects
Whole fruit	Anthocyanin component, Cyanidin-3-glucoside	↓TNF-α, ↓PAI-1, ↓MCP-1 and inhibition of monocytes	Zhao and Shen. (2023)
Whole fruit	Cyanidin-3-glucoside (C3G)	The supplementation of C3G in the HFHS diet: circulating levels ↑, MCP-1↑, PAI-1 ↑	Huang et al. (2020)
Whole fruit	Ethanol extracts	↓TNF-α	Nayak and Rempel. (2013)
Whole fruit	Bread fortified with STB powder (3%)	Bread fortified with STB powder (3%): inhibited pancreatic lipase and cyclooxygenase-2 activity	Lachowicz et al. (2020b)

Several antioxidant activity assays, including DPPH (2,2-Diphenyl-1-picrylhydrazyl), ABTS (2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), superoxide anion scavenging, hydroxyl radical scavenging, ORAC (oxygen radical absorbance capacity), and TRAP(total reactive antioxidant potential), have been employed to evaluate the antioxidant potential of STB. Tian et al. (2018) compared the antioxidant activity of whole fruits, leaves, and branches. The study found that all the extracts had 90% DPPH radical scavenging activity. However, the leaf extract showed the strongest ORAC activity (1015.2 ± 29.7 TE mg/100mL) and the highest TRAP value of 424.3 ± 33.2 TE mg/100 mL. A previous study found that the Northline exhibited the highest DPPH and ABTS radical scavenging activities of 23.1 ± 1.3 and 327.5 ± 5.2 mM TEAC/100 mg, respectively. The DPPH and ABTS radical scavenging activities of Martin were 14.7 ± 1.7 and 177.1 ± 4.4 mM TEAC/100 mg, respectively. In addition, the DPPH and ABTS radical scavenging activities of whole fruits were higher than those of pomace (Souza et al., 2019). Another study showed that peels have the highest antioxidant activity. It has a range of 32.3–57.9 mmol TE/100 g for DPPH radical scavenging activity and 14.5–41.5 mmol TE/100g for TRAP (Lachowicz et al., 2020a). Rop et al. (2013) investigated the antioxidant activity of the methanolic extract of whole fruits. The values of total antioxidant activity were 4.17–5.29g (Eq/kg). The extracts showed moderate inhibitory activity against nitric oxide (21.08% to 27.52%), superoxide anion (25.14% to 30.73%), hydroxyl radical (18.25% to 21.18%), and antioxidant activities in the liver lipid system (7.90% to 8.38%). The antioxidant activities of STB-fortified products were evaluated. A recent study found that adding 3% STB powder was microencapsulated and then added to the bread, it significantly increased its antioxidant activity (Lachowicz et al., 2021). STB was used as a beer flavor enhancer, and it significantly enhanced the antioxidant activity of beer (Gorzelany et al., 2022). Amelanchier lamarckii extract exhibited potent antioxidant activity with cupric ion-reducing antioxidant capacity value of 323.99 µmol Trolox/g and ferric reducing antioxidant power value of 4.10 μmol Fe²⁺/g (Dăescu et al., 2024). A recent study demonstrated that Saskatoon berries contain abundant bioactive compounds, particularly phenolics (including chlorogenic acid, quercetin, and cyanidin derivatives), and demonstrate significant antioxidant and antimicrobial properties (Sagandyk et al., 2024).

These results suggest that STB is an excellent natural antioxidant that could be used as a dietary supplement. However, the current studies were mainly based on in vitro antioxidant tests and did not reflect the actual mechanism of STB. Therefore, animal and human experiments are needed to confirm the antioxidant ability of STB in future studies.

Anti-inflammatory effect

In vivo studies are critical for understanding the potential health benefits of STB. Previous studies have demonstrated that whole fruit powders and extracts (lyophilized powder, anthocyanin component, cyanidin-3-glucoside, and ethanol extracts) can modulate proinflammatory markers and signaling pathways (Table 2). Various studies have demonstrated the anti-inflammatory effects of polyphenols (Burgos-Edwards et al., 2019; Tan et al., 2022). A previous study demonstrated that adding fortification enhancers (3% STB powder) to bread inhibited pancreatic lipase and cyclooxygenase-2 activity (Lachowicz et al., 2020b). Huang et al. (2020) founded that when cyanidin-3-glucoside was added to the high-fat, high-sucrose (HFHS) diet, it significantly lowered the blood levels of MCP-1 and PAI-1 in mice. Nayak and Rempel (2013) showed that STB ethanol extract had a strong TNF-α inhibitory effect on LPS-stimulated macrophages RAW264.7, which was similar to that of curcumin. Its inhibitory effect on TNFα is attributed to its high levels of phenolic compounds. Another study demonstrated that the anthocyanin component of STB and cyanidin-3-glucoside reduced inflammatory markers (TNF-α, PAI-1, and MCP-1) and inhibited monocytes (Zhao And Shen, 2023).

The current study focused on the components of STB polyphenols and their anti-inflammatory properties. However, few studies have investigated other potential active components of STB. Therefore, further studies should be conducted to explore the anti-inflammatory potential of STB polysaccharides and peptides.

Regulation of metabolic syndrome

Metabolic syndrome is a disease that includes abdominal obesity, impaired glucose metabolism, dyslipidemia, and hypertension. It can synergistically increase the risk of developing type 2 diabetes, cardiovascular disease and even death (Jun et al., 2022). STB and its extracts have been shown to reduce cholesterol, inhibit hepatic steatosis, regulate neuroendocrine function, reverse intestinal flora dysbiosis, and regulate insulin secretion, thereby achieving the regulation of metabolic disorders (Table 3).

Table 3.

Regulation of metabolic syndrome of different parts of Saskatoon berry

Parts	Sample	Result	References
Whole fruit	Lipophilic bioactive compounds	Possesses antihypertensive activity	Kodikara et al. (2024)
Whole fruit	Powder, anthocyanin component and protocatechuic acid	↑Bacteroidetes/Firmicutes (B/F) ratio, Increased the abundances of Bacteroidaceae, Muribaculaceae, and Ruminococcaceae Decreased the abundances of Lachnospiraceae in mouse feces	Zhao and Shen. (2023)
Whole fruit	Powder	↓Body weight, ↓visceral adiposity, ↓systolic blood pressure, ↓cardiac fibrosis ↓plasma total cholesterol ↓Plasma concentrations of triglycerides and non-esterified fatty acids ↓Plasma activities of alanine transaminase and aspartate transaminase Saskatoon berry powder normalized liver expression of hexokinase 1 and glycogen phosphorylase and increased glucose 6-phosphatase	Preez et al. (2020)
Whole fruit	Powder	Inhibition of α-amylase with IC50 values ranging from 18.33 to 31.70 mg/mL Inhibition of α-glucosidase with IC50 values were between 27.833 and 42.23 mg/mL. Inhibition of pancreatic lipase with IC50 values ranging from 88.20 to 132.63 mg/mL	Lachowicz et al. (2019a, b)
Flesh		Inhibition of α-amylase with IC50 values ranging from 22.53 to 42.15 mg/mL Inhibition of α-glucosidase with IC50 values were between 27.83 and 43.79 mg/mL. Inhibition of pancreatic lipase with IC50 values ranging from 81.90 to 123.15 mg/mL
Peel		Inhibition of α-amylase with IC50 values ranging from 11.05 to 18.41 mg/mL. Inhibition of α-glucosidase with IC50 values were between 23.60 and 37.06 mg/mL. Inhibition of pancreatic lipase with IC50 values ranging from 94.50 to 144.10 mg/mL
Seeds		Inhibition of α-amylase with IC50 values ranging from 33.08 to 55.12 mg/mL. Inhibition of α-glucosidase with IC50 values were between 59.89 and 90.87 mg/mL The seeds have no inhibitory activity against pancreatic lipase
Whole fruit	Cyanidin-3-glucoside (C3G)	↓Body weights, ↓glucose, ↓lipid, ↓plasma insulin, ↓insulin resistance ↓Relative abundance of Bacteroidetes, ↓relative abundance of Firmicutes, ↑relative abundances of Muribaculaceae family bacteria ↓Bacteroidetes/Firmicutes Ratio (B/F), ↑Firmicutes/Bacteroidetes ratio	Huang et al. (2020)
Whole fruit	Water extract	↓Acid soluble metabolite accumulation, ↓fatty acid oxidation rate, ↓CO2, ↓mitochondria	Kraft et al. (2008)
Leaves	Ethyl acetate and aqueous extracts	STB extract inhibits glucose absorption in vivo through the mechanism of inhibition of sucrase, maltase, and isomaltose activities of a-glucosidase. ↓Post-prandial glycemic	Zhang et al. (2012)

Zhao et al. (2015) explored the mechanism of action of STB powder and its anthocyanin extracts (cyanidin-3-glucoside: C3G, and cyanidin-3-galactoside: C3Ga) on the endoplasmic reticulum. The study demonstrated that STB powder reduced thioflavin T (ThT) fluorescence and unfolded protein response (UPR) markers (glucose-regulated protein 78/94), X-box binding protein-1, and C/EBP homologous protein) in the hearts and aortas of male diabetic db/db and C57BL/J wild-type mice. In addition, the inhibitory effects of C3G on ThT and UPR were stronger than those of C3Ga. This indicated that they are involved in the anti-endoplasmic reticulum stress effect of STB powder in diabetic mice. These results suggest that STB powder and its anthocyanin extracts can be used as potential functional supplements to prevent diabetes. Another research has demonstrated that STB supplementation normalizes body weight and fat, improves glucose tolerance, lowers systolic blood pressure, reduces inflammation, lowers total plasma cholesterol, and improves the structure and function of the heart and liver. In addition, it normalized the expression of hexokinase 1 and glycogen phosphorylase in the liver and increased glucose 6-phosphatase levels. These results indicate that STB can regulate glycolysis and gluconeogenesis, thereby improving metabolic syndrome (Preez et al., 2020). Another study indicated that the C3G of STB can reduce metabolic disorders and inflammation and modulate gut flora dysbiosis caused by a high-fat diet (Huang et al., 2020). Several researchers have used in vitro assays such as aldose reductase assay, α-glucosidase inhibition assay, and pancreatic lipase activity assays to assess the modulatory effects of STB extract on metabolic syndrome. They found that the STB extract alleviated metabolic disorders to varying degrees (Kraft et al., 2008; Zhang et al., 2012). A previous study reported that supplementation with STB powder, C3G, and protocatechuic acid significantly decreased high-fat-high-sucrose diet-induced metabolic markers. In addition, it increased the abundance of Bacteroidaceae, Muribaculaceae, and Ruminococcaceae and decreased the abundance of Lachnospiraceae in mouse feces (Zhao And Shen, 2023). A recent study demonstrated that Saskatoon berries display a unique phytosterol and terpene profile with potential antihypertensive activity (Kodikara et al., 2024). These comprehensive studies have established STB powder and its anthocyanins as promising therapeutic agents for metabolic syndrome and diabetes. The current research has predominantly focused on rodent models and in vitro experiments, necessitating a broader investigative scope to fully understand STB’s therapeutic potential. Future mechanistic studies should employ advanced omics approaches to elucidate the molecular interactions between STB components and establish clear structure–activity relationships. Expanded preclinical validation should include humanized mouse models, biomarker exploration, and multi-organ pharmacokinetic studies to improve the robustness of safety and efficacy evaluations. Clinical trials should incorporate multi-center designs, real-world evidence, and personalized treatment strategies to ensure broad applicability, optimal dosing, and sustained therapeutic benefits. The parallel development of standardized STB formulations and robust quality control methods is crucial to ensure consistent therapeutic efficacy and safety. This systematic research approach will address current knowledge gaps regarding the molecular mechanisms, bioavailability, and therapeutic efficacy of STB, providing a solid evidence base for its clinical implementation. This comprehensive investigation will enhance our understanding of STB’s therapeutic potential and support its translation into effective clinical interventions for metabolic syndrome and related disorders.

Antibacterial effect

Foodborne pathogens pose significant risks to public health and safety. One report stated that over 90% of deaths are caused by foodborne pathogens (Liu et al., 2022). The antimicrobial effects of STB extracts against fungi, bacteria, and harmful microorganisms have been extensively studied. Table 4 shows the antimicrobial activity of various STB extracts.

Table 4.

Antibacterial and other health effects of different parts of Saskatoon berry

Parts	Sample	Result	References
Antibacterial effects
Whole fruit	Extracts	Inhibiting bacteria-Enterococcus hirae growth and development. Antibacterial zone: 2.57–8.03 mm	Lachowicz et al. (2019a, b)
Flesh		The extracts of flesh, peel, and seeds had no antibacterial activity
Peel
Seeds
Whole fruit	Extracts (ethanol, water, acetic acid, 70:30:1, v/v/v)	Inhibiting the growth of Escherichia coli, Listeria monocytogenes, Staphylococcus aureus, and Bacillus cereus	Tian et al. (2018)
Leaf		Inhibiting the growth of Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, and Bacillus cereus
Branch		Inhibiting the growth of Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, and Bacillus cereus
Other health effects
Whole fruit	Powder	The Saskatoon berry (STB) diet supplementation did not reduce kidney weight, kidney water content, BP, and left ventricle weight The STB diet supplementation reduced cardiac remodeling and MDA concentration without altering the creatinine concentration The STB diet may be useful in preventing cardiac remodeling and oxidative stress	Raj et al. (2021)
Branch	Methanolic extract	Strong antiviral activity against bovine coronavirus	McCutcheon et al. (1995)

Tian et al. (2018) founded that the leaf extracts of RTB inhibited the growth of Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, and Bacillus cereus more strongly than the fruit and branch extract. In addition, whole fruit, leaf, and branch extracts of STB inhibited Salmonella enterica sv. Typhimurium. In another study, whole fruit extract of STB was found to inhibit the growth and development of only one bacterium (Enterococcus hirae) with a circle of inhibition of 2.57–8.03 mm. However, the pulp, peel, and seed extracts had no antimicrobial activity (Lachowicz et al., 2019a, b). This phenomenon may be due to the antimicrobial activity of the whole fruit due to the synergistic interaction of compounds in its various parts, higher concentrations of active ingredients, and protection of biological activity by the intact fruit matrix. This complex interaction may be lost when the fruit is separated into different parts, resulting in the inability of pulp, peel, and seed extracts alone to exert antimicrobial effects. More in-depth chemical analyses and compound interaction studies are required to elucidate this phenomenon.

These studies revealed the antimicrobial potential of RTB and STB extracts and significant differences between the extracts from different regions. Future studies should deeply analyze the chemical composition of each part, especially the differences between the whole fruit and the isolated parts. In addition, the mechanisms of interactions between different compounds should be explored as well as broader screening tests for antimicrobial profiles.

Other health effects

STB has also been documented to have other health benefits, including protection of the kidneys and anti-cardiac syndrome (Table 4). A study demonstrated that methanolic extract of the STB branch showed strong antiviral activity against bovine coronavirus (McCutcheon et al., 1995). The study found that supplementing the STB diet did not reduce kidney weight, water content, blood pressure, or left ventricular weight. In addition, supplementation with the STB diet reduced cardiac remodeling and malondialdehyde concentrations but did not alter creatinine concentrations (Raj et al., 2021). These results suggest that the STB diet may help prevent cardiac remodeling and oxidative stress. In addition, supplementation with STB did not have other adverse effects on animal organs or on other metabolic activities.

Shelf-life extension techniques for STB

This section focuses on techniques to extend the shelf-life of fresh STB. Fresh ripe STB fruit has a high moisture content (82%–84%) and a short shelf life (10–14 days) (Nagalakshmi et al., 2014). They will decay and spoil within a few days if not preserved properly (Meda et al., 2016). Microbial action (such as bacteria, molds, and yeasts), oxidative reactions, enzyme activity, physical damage, and water loss through evaporation are common factors leading to postharvest decay and deterioration of fruits (Romanazzi et al., 2016; Anand And Barua, 2022). Shelf-life extension of STB is crucial for broadening the utilization of the fruit. different process parameters and mechanisms of shelf-life extension affect not only the physicochemical properties of the fruit but also its nutritional and antioxidant properties. Therefore, the fruits need to be processed using appropriate techniques to extend their shelf life and maintain their nutrient quality.

Low-temperature storage

Low-temperature storage including refrigeration and frozen storage, are common techniques for preserving foods, fruits, and vegetables for long periods. Freezing is widely acknowledged as a primary technique for the extended preservation and preservation of fruits because of its minimal effect on nutritional value (Neri et al., 2020). Low temperature slows down the rate of chemical reactions, microbial growth, and biodegradation processes, thus prolonging their shelf life (Kulus, 2019). There were no significant differences in the aroma, flavor, sweetness, or overall flavor intensity of STB when the fruits were stored for 5 days at 4 °C (Kidd, 2007). Bakowska-Barczak and Kolodziejczyk (2008) reported that after 9 months of storage at – 20 °C, 17 varieties of STB showed a slight decrease (< 5%) in total polyphenol content. During the cold storage, the antioxidant activity of 16 STB varieties, except for Smokey, remained unchanged with DPPH and ABTS radicals 2.8 and 5.0 mM/100g, respectively. Michalczyk and Macura (2010) compared the effects of frozen storage and pasteurization on the storage characteristics of STB. The study demonstrated that the anthocyanins of the fruit were well preserved after 10 months at – 20 ℃. However, the pasteurization was performed out at two temperatures, 85 °C and 100 °C for 15 min, which significantly reduced the total anthocyanins after 10 months of storage at 22 ℃. In addition, the EC₅₀ of DPPH free radical scavenging activity of fresh fruits was 21 mg/100g. The EC₅₀ of DPPH of the frozen-stored fruit slightly reduced. However, The EC₅₀ of DPPH free radical of pasteurization was increased by twofold compared with fresh fruits. It is therefore concluded that freezing can be used as a technique for preserving the quality of STB. Nevertheless, freezing is a high-energy consumption technology that results in expensive preservation for long-term storage. Therefore, the exploration of new preservation technologies for STB applications, such as edible coatings and films, nanotechnology applications, and smart packaging, is necessary.

Ozone treatment

Ozone treatment inhibits various microorganisms and is an effective technology for extending shelf life (Botondi et al., 2021). A recent study demonstrated that ozone treatment reduced the number of aerobic mesophilic bacteria, yeasts, and molds on fruit. It effectively extended the STB shelf life (Gorzelany et al., 2022). However, the effects of ozone treatment on other nutrients such as vitamins and phytochemicals have yet to be studied and thus should be the focus of future research.

Drying treatment

Drying can effectively improve the shelf life of food. The preservation of food is achieved via reduction of moisture content and water activity, thus inhibiting the propagation of microorganisms and enzymatic activity in the food (An et al., 2022). Nagalakshmi et al. (2014) found that vacuum microwave drying increased the L^* value of STB compared with freeze drying. A shorter drying time resulted in minimal effect on the total color difference value. However, the fruit became harder, chewier, and gummier with increasing microwave power and drying time, whereas its cohesiveness and springiness decreased. In contrast, another study showed that increasing microwave power, drying time, and decreasing loading could increase the rehydration activity of STB. In addition, it leads to an increase in the hardness and total color difference in STB (Meda et al., 2016). In a recent study, Lachowicz et al. (2019a, b) found that the highest retention of polyphenolic compounds was obtained with microwave vacuum drying (MVD), followed by convective drying/microwave vacuum drying (CD/MVD) and CD. Furthermore, VMD had the same qualities as freeze drying (FD), especially regarding the retention of polymeric procyanidins and flavanols in STB. It was noted that VMD can reduce the drying time by 20 times compared with FD. Thus, VMD is suitable for drying STB. Current research has focused on studying the physical properties of STB. However, the impact of drying conditions namely drying time, temperature, and vacuum on the nutritional properties of STB remains to be investigated. Furthermore, STB peel is a protective layer that obstructs moisture removal, leading to longer drying times and poorer product quality. Study on pretreatments technique prior to drying in order to enhance permeability of the peel should be explored. Novel non-thermal pretreatment techniques, such as ultrasound, pulsed electric field, and cold plasma, are expected to increase moisture diffusion and drying rates. This shortens the drying time, thereby improving the quality, functionality, and stability of dried STB.

Applications of Saskatoon berries and their components

STB is rich in nutrients and phytochemicals and has great potential for the development of various foods. Besides being processed in conventional food products, STB can be used as a flavor enhancer and functional ingredient to develop new food products. They impart additional flavor and nutrient content to foods and improve their quality and functional properties. Moreover, they are also used in cosmetics. In this section, the current and potential utilization of STB and its components for food-related applications is reviewed (Fig. 2B).

Conventional food

STB can be eaten fresh or added as a part of ingredients in cakes, puddings, pies, fruit plates, decorations, and other desserts. STB-based products currently sold in Canada include dried fruit, jams, syrups, juice, wine, and liqueur (Fang, 2021). Several researchers reported the use of STB in production of drinks such as juice and alcoholic beverage. Vuong et al. (2006) investigated the bioactivity of fermented STB juices fermented with Serratia vaccinii at 22 ℃ for 10 days. The study found that the fermented STB juice has a good antioxidant activity and strong inhibition of nitric oxide (NO) production by lipopolysaccharide or interferon-gamma-activated macrophages. The seed oil of STB has beencextracted and characterized. Bakowska-Barczak et al. (2009) processed STB seeds into oil using the physical pressing method and analyzed the chemical composition of the oil. The linoleic acid content in STB seed oil was 47.3%, and the total tocopherol content ranged from 1053 to 1754 mg/kg. These findings suggest that STB seed oil can be used in the food and cosmetic industries owing to its high content of essential fatty acids and antioxidants.

Flavor enhancer

Flavor enhancers are compounds used to enhance the taste and flavor of food (Vasilaki et al., 2022). Grant et al. (2017) investigated the effect of the addition of commercially available Saskatoon berry syrup (STBS) on the flavor and consumer acceptance of rooibos (RT) and green tea (GT). The study found that adding STBS to RT and GT significantly increased the sweetness, aftertaste, and overall acceptability. In addition, it reduced the bitterness and astringency of RT and GT. Another study demonstrated that STB fruits can be flavor enhancers in fruit beer production. Barley beers brewed with ripe STB fruit flesh enhance the organoleptic characteristics of the beer (taste, fruitiness, and aroma), balance bitterness, and give the beer a better color (Gorzelany et al., 2022). The addition of lyophilized Saskatoon berries to bread showed relatively weaker gas retention capacity than elderberries and led to decreased bread volume with increasing addition levels. However, at a moderate addition level (5%), the bread still achieved acceptable sensory properties, particularly in flavor characteristics (Kolesárová et al., 2024). Despite the potential of STB as a flavor enhancer, some limitations of the current research. Research has focused on a narrow range of products (mainly beverages and bakery products), and there is limited understanding of the mechanisms of flavor modulation and STB stability during processing. In addition, optimal concentrations vary widely among food matrices, and standardized application protocols are lacking. Future research should investigate the mechanisms of flavor modulation by STBs and the stability of the compounds during processing and storage; expand the scope of application to a wide range of food categories beyond the current applications; and optimize the concentration levels to balance the relationship between flavor enhancement and product quality. This systematic approach will facilitate the wider use of STB as natural flavoring agents in the food industry.

Functional ingredient

Saskatoon berry antioxidant capsules are already commercially available in Canada. According to the product description, the main medicinal ingredient in the antioxidant capsules is dried STB fruit (827 mg), and the non-medicinal ingredients are hypromellose, magnesium stearate, and maltodextrin. The product is claimed to be a source of antioxidants that help protect cells from oxidative damage caused by free radicals. A bio-company in Thailand has developed an anti-acne cream using STB whole fruit extract, whose main function is to help reduce inflammation and acne irritation.

One of the most popular foods is bread. Most breads are made with wheat, while other types of flour such as soy, potatoes, and rye are also used. However, bread production often faces several challenges, such as lack of nutritional simplicity and color stability, which can be significantly improved by the addition of nutritional enhancers (Peñalver et al., 2020). STB is a good source of polyphenols, which can be supplemented in bread to improve its quality and bioaccessibility. Lachowicz et al. (2020b) reported that nutritional fortification at 3% (STB fruit powder) improved sensory attributes and color of bread. Bread containing STB fruit powder is characterized by the high bioavailability of flavan-3-ols, phenolic acids, and anthocyanins. In addition, STB fruit powder increased the inhibitory activity of bread against α-amylase, α-glucosidase and lipoxygenase. In a further study, Lachowicz et al. (2021) found that found that the addition of 6% STB freeze-dried powder to wheat bread significantly increased its phenolic content and antioxidant activity. The addition of STB powder reduced the digestibility of starch and protein. In addition, the addition of STB powder enhanced the inhibition of cyclooxygenase-1 and -2 and increased the inhibition of lipoxygenase, α-amylase, α-amylase, and pancreatic lipase activities of bread. Kolesárová et al. (2022) investigated the effect of STB freeze-dried powder (ripe whole fruit) addition on cookie quality. The results showed that replacing 10% of wheat flour with STB powder improved the appearance and texture of the cookies and imparted a berry color. STB powder is rich in polyphenols, significantly enhances the nutritional quality and bioaccessibility of baked goods. In addition, STB powder can act as a natural colorant, improving the sensory attributes and color stability of baked goods. Another study explored the incorporation of Saskatoon berry juice into whey beverages through thermostatic coagulation, which achieved significant nutritional enhancement, particularly in vitamin B3, calcium content, and energy value, while maintaining microbiological safety and improved carbohydrate content compared with processed whey, demonstrating its potential as a functional beverage formulation (Zhakupova et al., 2023). A recent study showed that Saskatoon berry powder can be successfully incorporated into functional foods, such as Greek-style frozen yogurt, retaining key bioactive compounds, including volatile organic compounds and phenolic acids. However, sensory properties, particularly texture and aroma, must be further optimized (Ryland et al., 2024). The co-encapsulation of Saskatoon berry pomace polyphenols with probiotics demonstrated a potential strategy for functional ingredient development, where polyphenolic compounds (TPC: 2.49 mg GAE/1 g) enhanced probiotic survival (9.08 log CFU/mL) in the gastrointestinal tract (Sharma et al., 2024). However, the application of spray-dried powder was constrained by its limited dispersibility properties, suggesting the need for further optimization of carrier materials and processing parameters for broader food applications. Future research should prioritize optimizing the function of STB as a food ingredient along a number of dimensions: technical (improving dispersion, stability and processing methods), product development (expanding the range of applications beyond current bakery and dairy products, investigating interactions with different food matrices), organoleptic properties (enhancing color stability, texture and flavor profiles), as well as the development of cost effective production methods and the establishment of standardized operating procedures. Particular attention should be given to the development of advanced encapsulation technologies and delivery systems to protect bioactive compounds while ensuring uniform distribution in food. There is also a need to study the effect of different processing parameters on the functional properties of STBs and to establish optimal levels of incorporation for various food applications to maximize technical functionality and consumer acceptance. This systematic approach will facilitate the wider commercial adoption of STB as a value-added functional ingredient in the food industry.

Potential utilization of STB

STB is considered a superfruit because of its rich nutritional properties. There have been several achievements in the processing and applications of STB. However, most current research focuses on the traditional food products and polyphenols of STB, the novel utilization and development of functional ingredients from STB components, such as dietary fibers polysaccharides, and anthocyanins, are limited. Therefore, further research on STB is required to explore more possibilities. The anthocyanins from STB can be extracted as natural coloring agents to enrich the color and taste of food. Furthermore, anthocyanins are particularly sensitive to pH, showing red or pink color under acidic conditions, and change to blue or purple under alkaline conditions. The possibility of incorporation of STB anthocyanins into biopolymer films can be further explored. It can be used as quality indicators to monitor changes in seafood, fruits, and vegetables during storage. The processing of ripe STB into juice produces a large quantity of pomace, which is normally disposed of as waste or used as animal feed. The pomace contains a large amount of dietary fiber (DF) (Valencia-Hernandez et al., 2021). DF has many health benefits, including promoting gut health (Cui et al., 2019), regulating blood sugar levels (Russell et al., 2016), lowering blood lipids (Surampudi et al., 2016), and preventing colon cancer (Hidaka et al., 2020). Thus, the biological properties and applications of dietary fibers in STB pomace should be thoroughly investigated in the future. This approach will be an effective strategy for not only to introduce a new source of DF for commercial utilization, but it provides a sustainable development of STB fruit pomace, aiming to reduce environmental pollution. STB seeds are rich in sterols. However, their research is limited. There is currently no evidence of toxicity associated with plant sterols (Plat et al., 2019). Therefore, it is considered to be a highly promising functional ingredient. Plant sterols have been described previously as having various biological activities. However, whether the key factor for their biological activity is a chemical characterization, or physiological effects still being determined is unclear. Therefore, studying the structural-activity relationship between sterols is important for future research.

The comprehensive development of STB as a functional food and medicinal resource faces several challenges that require systematic investigation. These challenges span multiple aspects of research and development, from fundamental safety assessments to industrial applications. Product development of STB faces the challenges of process optimization, compound characterization, toxicological evaluation, and structural activity relationship elucidation. Transitioning from traditional foods to validated functional ingredients requires robust safety and efficacy evidence. The current safety assessments lack systematic toxicological evaluations through both in vitro and in vivo studies. While cell culture studies have demonstrated the potential bioactivities of STB compounds, the absence of comprehensive safety data, particularly regarding long-term consumption and potential interactions with medications, poses a significant barrier to their commercial development. The limited clinical evidence base represents another critical gap. Although preliminary studies using polyphenol extracts have shown potential effect in animal models, particularly regarding their anti-inflammatory and antioxidant effects, human clinical trials are notably scarce. Future research priorities should include standardized safety protocols that align with international regulatory requirements and alongside well-designed randomized controlled trials investigating specific health claims. Additionally, comprehensive bioavailability studies in human subjects and thorough investigation of potential contraindications and drug interactions are essential to establish STB's safety and efficacy profile.

Except for safety considerations, there are significant gaps in the current understanding of the chemical composition and biological activity of STB. Although significant research has been conducted on the polyphenols of STB, other potentially valuable compounds remain to be explored. Previous studies have extensively characterized the polyphenolic content and functional properties of STB, focusing particularly on specific anthocyanins such as cyanidin-3-glucoside (C3G) and cyanidin-3-galactoside (C3Ga). Although these individual compounds have shown potential biological activity, current research approaches have focused on single components rather than their synergies. A full understanding of the bioactivity and functional properties of STB requires a systematic assessment of the structure–activity relationships and potential synergies among various bioactive components. To address these research gaps, advanced separation and characterization techniques are needed to isolate and identify novel bioactive compounds, assess their interactions, and establish standardized analytical methods for quality control. These techniques should focus on the isolation and characterization of novel bioactive compounds, particularly proteins, carbohydrates, and sterols, along with the determination of structure–activity relationships of individual compounds. In addition, the assessment of potential synergistic effects between different components and the development of targeted extraction methods for specific bioactive fractions are critical areas of research. Recent advances in separation techniques, such as supercritical fluid extraction and membrane filtration, offer viable methods for more efficient and selective separation of compounds, making it possible to develop standardized extracts with bioactive profiles.

Another significant challenge is the commercialization of STB. The seasonal availability and perishability of STB represent significant barriers to its commercial adoption. Current storage methods are insufficient to maintain year-round supply while preserving bioactive compounds. This technical limitation has broad implications for product development and market expansion. Several innovative approaches show promise in addressing these preservation and processing challenges. Smart preservation techniques incorporating modified atmosphere packaging and bioactive coatings, combined with advanced drying methods that maintain nutritional value while extending the shelf life, represent promising directions for further development. Green extraction technologies for valuable compounds from by-products further enhance the potential for sustainable processing. The valorization of STB waste, particularly peels and seeds, represents an important opportunity for sustainable processing. Recent studies have demonstrated the potential of extracting anthocyanins from peels to produce natural colorants and developing improved methods for seed oil extraction. However, these processes require optimization for industrial scale implementation.

In the future, research emphasis should focus on establishing comprehensive safety protocols and initiating human clinical trials while simultaneously developing and validating advanced analytical methods for compound characterization. The scaling up of promising preservation and extraction technologies, coupled with an investigation of sustainable processing methods for whole-fruit utilization, will provide a foundation for the evidenced development of STB products while addressing current technological limitations. Success in these areas will enable the translation of STB’s promising properties into commercially viable functional foods and nutraceuticals. Through focused research efforts in these key areas, the full potential of STB as a valuable resource for both nutritional and medicinal applications can be realized, leading to innovative products that meet modern market demands while maintaining scientific rigor and safety standards.

Funding

Open access funding provided by The Ministry of Higher Education Malaysia and Universiti Putra Malaysia.

Data availability

No data was used for the research described in the article.

Declarations

Conflict of interest

The authors declare no conflict of interest. All authors have read and agreed to the published version of the manuscript.