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Journal of Food Science and Technology logoLink to Journal of Food Science and Technology
. 2020 Aug 27;58(6):2360–2367. doi: 10.1007/s13197-020-04748-0

Nutritional values of Baccaurea pubera and comparative evaluation of SHS treatment on its antioxidant properties

Syafiqah Shaharuddin 1, Rafidah Husen 2, Azizah Othman 1,✉
PMCID: PMC8076416  PMID: 33967332

Abstract

Baccaurea pubera is a blood red coloured fruit found exclusively in Borneo. This study was conducted to evaluate the effect of superheated steam treatment on its antioxidant properties and mineral content as well as to determine nutritional values of the fruit. The fruits were treated with superheated steam at 170 °C for 15 min prior to extraction and freeze drying. The results showed that, in comparison to the control, superheated steam treatment enhanced the total phenolic content by 147.8% (287.16 mg GAE/100 g vs. 115.87 mg GAE/100 g) and DPPH radical scavenging activity by 23.7% (66.94% vs. 54.13%). However, there were reductions, as compared to the control treatments, in total flavonoid content by 16.5% (8.29 mg QE/100 g vs. 9.93 mg QE/100 g), lycopene content by 28.6% (0.020 μg/100 g vs. 0.028 μg/100 g) and ferric reducing antioxidant power by 22.2% (844.41 mg TE/100 g vs. 1085.15 mg TE/100 g). The superheated steam treatment was also observed to reduce the mineral content of the fruit, from as little as 3.6% to as high as 52% depending upon the specific mineral.

Keywords: Baccaurea pubera, Superheated steam treatment, Nutritional values, Antioxidant capacity

Introduction

Malaysia is home to diversified natural resources, flora, and fauna. Some fruits in the country are consumed but not studied sufficiently for commercialized applications. Lack of data on nutritional composition and practices of production and postharvest for such fruits have prevented their commercialization (Ikram et al. 2009; Shakirin et al. 2010). Kejirak fruit [Baccaurea pubera (Miq.) Mull. Arg.] is one of the underutilized fruits belonging to the Euphorbiaceae family and locally known as ‘red tampoi’ due to its blood red pulp (Fig. 1).

Fig. 1.

Fig. 1

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B. pubera fruits

The taste of B. pubera is reported to be refreshingly sweet and tangy (Hoe and Siong 1999). To date, very limited studies have been reported on this particular underutilized fruit. Other underutilized fruits of the same Baccaurea family, namely B. angulata (belimbing hutan), B. motleyana (rambai), and B. polyneura (jentik–jentik) have been reported to have antioxidant properties (Ahmed et al. 2015; Ikram et al. 2009). B. pubera is a seasonal fruit, and its availability is very limited but abundantly available when in season. Processing the fruit into food products will make this fruit more available to consumers. However, processing measures can normally affect the nutritional content of the fruits.

In fruit extraction, pre-treatment steps are applied to resolve issues, such as poor solvent diffusion; the release of covalently bonded phenolic compounds with other components like proteins, cellulose, and lignin; low solubility of lipophilic phytochemicals; cell wall interferences; large amounts of organic solvents used; and extended extraction time (Stamatopoulos et al. 2012). Raw materials are treated to minimize the matrix effects on the extractability of phenolic compounds. However, water-soluble phenolic compounds are lost when treating samples using heat due to leaching during blanching; furthermore, elevated temperatures degrade phenolic compounds.

Superheated steam (SHS) is dry steam with a temperature higher than the saturation temperature for that particular steam pressure. SHS has been used as a drying method for food, such as potatoes, sugar beet pulp, shrimps, and spent grain. The approach may be used as an alternative heat pre-treatment to water blanching due to the utilization of steam; hence, the approach may be able to reduce the leaching of water-soluble pigments from fruits in water blanching, thus producing better yield. Stamatopoulos et al. (2012) reported that steam blanching pre-treatment of olive leaves before extraction increased the yield of oleuropein significantly, by 25–35 times. An SHS oven provides an oxygen-deficient environment, thus providing better protection toward oxidative loss of bioactive components (Sehrawat et al. 2018). Furthermore, SHS is able to maintain the color, texture, and rehydration of products (Sehrawat et al. 2018).

This study aims at evaluating the nutritional composition of B. pubera and its antioxidant properties influenced by the SHS pre-processing treatment.

Materials and methods

Chemical and reagents

Aluminium chloride hexahydrate, sodium acetate trihydrate, acetic acid, petroleum ether, Trolox, gallic acid and quercetin standards, and DPPH (2,2-diphenyl-2-picrylhydrazyl) were purchased from Sigma-Aldrich, Germany. Meanwhile, 95% ethanol, pH buffer 4, pH buffer 7, and ICP multi-element standard were obtained from Merck, Germany. Hydrogen peroxide, sulfuric acid, nitric acid, boric acid, hydrochloric acid, acetone, and Folin-Ciocalteu reagent were acquired from R&M Chemicals, United Kingdom. Sodium carbonate and TPTZ (2,4,6-tripyridyl-s-triazine) were obtained from Ajax, New Zealand and Fluka, Germany, respectively. Finally, ferric chloride hexahydrate and hexane were purchased from HmbG GmbH, Denmark.

Fruit sample

2 kg of fresh B. pubera was collected in Sarawak, Malaysia at its commercial ripening stage. The fruits were divided into two groups: the SHS-treated (SHST) group subjected to SHS treatment and the control (untreated) group. SHS treatment was done according to Rafidah et al. (2014) with slight modification, where the fruits were exposed to SHS at 170 °C for 15 min using an SHS oven (DC Quto QF-5200C, Naomoto, Japan).

Extraction of phenolic compounds

Phenolic compounds in the fruit samples were extracted with 80% ethanol (v/v) at a ratio of 1:10. The extraction was performed according to the methods of Ikram et al. (2009) with slight modification. The mixture was shaken for 2 h at 200 rpm and 28 °C using an incubator shaker (Innova 40, Eppendorf, Germany), filtered, and evaporated under vacuum at 175 mbar using a rotavapor (RE21, Büchi, Switzerland) with water bath temperature of 25 °C. Next, the liquid extract was lyophilized at − 60 °C in a freeze dryer (Alpha 1-4 LD plus, Martin Christ, Germany) for 7 days, according to the drying method of Rafidah et al. (2014). The dried extracts were stored at − 30 °C for further analysis of the antioxidant properties of the fruit.

Physicochemical properties

Proximate analysis was performed on fresh B. pubera. The proximate composition was determined according to the AOAC method. The color of the fruits was determined using a chromameter (CR-400, Konica Minolta Sensing Inc., Japan). The parameters determined were L*, a*, and b*. Meanwhile, pH was measured using a pH meter (HI 2211 pH/ORP meter, Hanna Instruments, USA).

Total phenolic content

Total phenolic content (TPC) was determined according to the method of Othman et al. (2014). 200 µL of each untreated and SHST extract was pipetted into an amber test tube. 1.5 mL of Folin-Ciocalteu reagent diluted by ten-fold using distilled water was added and mixed. The mixture was allowed to stand at room temperature for 5 min. Then, 1.5 mL of 0.56 M sodium carbonate (Na2CO3) solution was added to the mixture and left to stand for 90 min at room temperature in dark condition. After 90 min, the absorbance of the mixture was determined using an ultraviolet–visible (UV–vis) spectrophotometer (Thermo Scientific, Thermo Fisher Scientific, USA) at 725 nm. The measurements were compared to a standard curve of gallic acid and the results were expressed as milligrams of gallic acid equivalents (GAE) per 100 g edible portion.

Total flavonoid content

Total flavonoid content (TFC) was determined using the method outlined by Djeridane et al. (2006) based on the formation of flavonoid-aluminum. 1 mL of sample extract was mixed with 1 mL of 2% aluminum chloride-6-hydrate (AlCl3·6H2O) solution. The mixture was incubated at room temperature for 15 min. After the incubation period, the absorbance of the mixture was measured using a UV–vis spectrophotometer (Thermo Scientific, Thermo Fisher Scientific, USA) at 430 nm. The measurements were compared to a standard curve of quercetin concentrations and expressed as milligrams of quercetin equivalents (QE) per 100 g edible portion.

DPPH radical scavenging activity

Free radical scavenging activity against 2,2-diphenyl-2-picrylhydrazyl (DPPH) radicals was determined using the method of Oboh (2005). 1 mL of ethanolic extract was added to 2 mL of 0.15 mM DPPH and mixed thoroughly on a vortex mixer (REAX Control, Heidolph, Germany). The mixture was left in a dark place for 30 min. After the incubation period, the absorbance of the mixture was measured at 517 nm using a UV–vis spectrophotometer (Thermo Scientific, Thermo Fisher Scientific, USA) against 80% ethanol as blank. The mixture of 80% ethanol and DPPH solution acted as a control, and ascorbic acid was used as a comparative standard. The antioxidant activity was expressed as the percentage of scavenging activity using the following formula:

Percentageofscavengingactivity(%)=Acontrol-AsampleorstandardAcontrol×100 1

where

  • Acontrol is the absorbance of the mixture of 80% ethanol and DPPH solution, and

  • Asample or standard is the absorbance of the sample or standard mixed with the DPPH solution.

Ferric reducing antioxidant power assay

Ferric reducing antioxidant power (FRAP) was measured using the method described by Benzie and Strain (1996). FRAP is based on the reduction of Fe3+-TPTZ (2,4,6-tripyridyl-s-triazine) complex into a blue ferrous compound at low pH. In the method, a FRAP reagent was freshly prepared by mixing 300 mM acetate buffer (pH 3.6), 10 mM TPTZ solution, and 20 mM ferric chloride hexahydrate (FeCl3·6H2O) solution in the ratio of 25:2.5:2.5. The reagent was incubated at 37 °C for 10 min. After that, 100 µL of 1.5 mg/mL ethanolic extract was mixed with 8.7 mL of the freshly prepared FRAP reagent and incubated in a dark place at 50 °C for 1 h. The absorbance of the mixture was determined after 1 h at 593 nm. The measurements were compared with a standard curve of Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid). The result was expressed as milligram Trolox equivalent (TE) per 100 g edible portion.

Lycopene content

The concentration of lycopene in B. pubera extract was measured according to the procedure modified by Amiri-Rigi and Abbasi (2016). Lycopene was extracted by adding 0.5 g of the fruit extract to a solvent containing hexane:ethanol:acetone in the ratio of 2:1:1 to the final volume of 20 mL. This procedure was done at room temperature under reduced light condition. The mixture was placed in an incubator shaker (Innova 40, Eppendorf, Germany) at 27 °C and 300 rpm for 15 min. Then, 3 mL of deionized water was added to the mixture and the solution was further shaken for another 5 min. The suspension was left to stand at room temperature for 5 min or until the spontaneous separation of polar and non-polar phase completed. The upper (non-polar) phase was transferred into an amber tube and the lower (polar) phase was re-extracted until it decolorized. The upper phases from each extraction were combined. The decolorization of the lower phase after several extractions indicated that lycopene was present in the sample. The amount of lycopene was measured after the confirmation. The absorbance of the non-polar phase was recorded at a wavelength of 503 nm using hexane as blank in a UV–vis spectrophotometer (Thermo Scientific, Thermo Fisher Scientific, USA). The lycopene content in the extract was calculated as follows:

Lycopene(μg/g)=A50317.2×104×1b×536.9×1L103mL×106μg1g×VmLkg×kg103g 2

where

  • A503 is the absorbance of the non-polar phase at 503 nm,

  • 17.2 × 104 is the molar extinction coefficient for lycopene in hexane (L/mole cm),

  • b is the path length (1 cm),

  • 536.9 g/mol is the molecular weight of lycopene (g/mole), and

  • V is the volume of non-polar phase (mL).

Mineral content

Mineral content was determined using the method of Kumaravel and Alagusundaram (2014) with slight modification using inductively coupled plasma-optical emission spectrometry (ICP-OES) (Optima DV2100, Perkin-Elmer, USA).

Statistical analysis

All experiments were performed in triplicates. The results were expressed as mean ± standard deviation (SD). The data were analyzed using independent samples t test to determine the difference between the two extracts using SPSS version 23 (SPSS Inc., Chicago, IL, USA). For antioxidant activities, the data were analyzed using analysis of variance (ANOVA). Pearson correlation was used to assess the relationships between TPC, TFC, and antioxidant activities (i.e., DPPH and FRAP). The significance level was set at p < 0.05.

Results and discussion

Physicochemical properties of B. pubera

Proximate composition

The proximate composition of B. pubera was expressed as a percentage (%), as shown in Table 1. The proximate composition of B. pubera reported by Hoe and Siong (1999) also showed a nearly identical result. The slight difference might be due to the genetic origin of species, cultivation techniques, and environmental factors, such as the climate and temperature (Jamil et al. 2010). According to Kahoun et al. (2016), there are differences in the chemical composition of honey, depending on the production year, region, and different climatic and geographical factors, even if the honey is derived from the same floral sources. No details on the methods used were given in the study by Hoe and Siong (1999). The difference in the methods of analysis used could contribute to the differences in the nutrient composition.

Table 1.

Physicochemical properties of B. pubera fruit

Analyses Result Hoe and Siong (1999)
Moisture content (%) 60.24 ± 0.86 65.7
Fat (%) 3.84 ± 0.08 4.7
Protein (%) 3.09 ± 0.84 1.7
Carbohydrate (%) 28.83 ± 0.05 25.5
Ash (%) 4.00 ± 0.14 0.8
Energy (kcal) 161.84 ± 1.52 151
pH 3.68 ± 0.02 –
Colour –
 L* 34.25 ± 0.83
 a* 19.65 ± 2.36
 b* 11.63 ± 1.56
Lycopene (µg/100 g) 0.16 ± 0.01 –
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Results were expressed as mean ± standard deviation (n = 3)

pH and color

The pH level of B. pubera was acidic at the value of 3.68. This value is comparable to the pH of peaches (pH 3.4–3.6), blueberries (pH 3.7), red cherries (pH 3.25–3.82), raspberries (pH 3.2–3.7), and grapes (pH 3.4–4.5) (US Food & Drug Administration 2012). The acidity in most ripe fleshy fruits is mainly due to the presence of organic acids that contribute to flavor, and positively affect digestion and other biochemical processes in humans (Švarc-Gajić et al. 2018).

Meanwhile, the color analysis of B. pubera showed positive a* (redness) and positive b* (yellowness) values. This result indicated that B. pubera was in the red direction with a yellow hue. Many plants or fruits with natural red pigments contain lycopene. Examples of red colored fruits containing lycopene are tomato, watermelon, pink grapefruit, guava, and papaya. The lycopene content in B. pubera was 0.16 µg/100 g dried edible portion. An example of fruit containing lycopene is apricot, which contains 10 µg lycopene/100 g wet weight (Rao and Rao 2007).

Extraction yield

The percentage yield obtained was 16.68% and 9.37% for untreated and SHST fruit extracts, respectively. From the result, the treatment reduced the extraction yield compared to the control. This is because the untreated B. pubera is not being subjected to heat treatment. Hence, for the extraction, other compounds such as carbohydrates (i.e., glucose and fructose), water-soluble vitamins, and other volatile elements were extracted together from the untreated sample. However, in the SHST B. pubera, the compounds may have already degraded due to the thermal treatment applied. Thus, the weight of the dried extract of untreated B. pubera is higher than the SHST B. pubera. Nevertheless, the SHST extract has better quality in terms of TPC and DPPH scavenging activity than the untreated extract. The SHST extract has good antioxidative properties although SHS treatment produced a lower yield of extract.

Total phenolic content and total flavonoid content

The TPC and TFC of B. pubera extract are shown in Table 2. For the untreated group, the TPC (115.87 ± 35.11 mg GAE/100 g) was comparable to the TPC of its closely related species, B. angulata (153.6 GAE/100 g edible portion) (Ahmed et al. 2015), and other underutilized fruits, such as durian hutan (Durio sp.) at 113.95 mg GAE/100 g edible portion, and pulasan kuning (Nephelium ramboutan-ake) at 144.67 mg GAE/100 g edible portion (Ikram et al. 2009). On the other hand, the TFC (9.93 ± 0.40 mg QE/100 g) of the untreated B. pubera extract was significantly higher compared to the TFC of its closely related species, B. angulata (0.37 mg QE/100 g edible portion) (Ahmed et al. 2015).

Table 2.

Antioxidant properties of untreated and SHST B. pubera extracts

Sample Antioxidant properties
TPC (mg GAE/100 g) TFC (mg QE/100 g) DPPH (%) FRAP (mg TE/100 g) Lycopene (µg/100 g)
Untreated B. pubera 115.87 ± 35.11b 9.93 ± 0.40a 54.13 ± 1.05b 1085.15 ± 12.23a 0.028 ± 0.0013a
SHST B. pubera 287.16 ± 44.01a 8.29 ± 0.28b 66.94 ± 0.65a 844.41 ± 7.18b 0.020 ± 0.0009b
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Data were expressed as mean ± standard deviation (n = 3). The values in different rows with different letters indicate significant difference at p < 0.05

The effects of SHS treatment on the TPC and TFC of B. pubera extract are also presented in Table 2. The TPC of the SHST B. pubera extract increased by almost 2.5 folds compared to the untreated B. pubera extract (Table 2), which was more than three times higher than the increase in SHS dried avocado pulp (Rafidah et al. 2014). SHS may have disrupted the cellular structure of the fruits, hence resulting in more antioxidant components released from the pulp (Huang et al. 2006). Noda et al. (2013) also reported an increase in the TPC of onions as the steaming time at high pressure increased. The authors proposed that employing high temperature and pressure steam for steam explosion, followed by rapid decompression to atmospheric pressure, reduced polyphenols to low molecular weight compounds and dissolved as phenolic compounds in water.

In contrast, the TFC of B. pubera extract dropped by 16.5% when subjected to SHS treatment. The decrease in the amount of quercetin, which is a type of flavonoid, due to steam processing has also been reported. It is suggested that the flavonoids might have leached out into the water and discarded at the end of the process (Harris et al. 2015; Lombard et al. 2005). Prommuak et al. (2008) also suggested that the amount of TFC is influenced by its glycosidic forms. The authors stated that flavonoids are usually present in glycosidic forms. However, deglycosylation of flavonoids may have occurred when the sample is subjected to pre-treatment with severe steam explosion, thus reducing flavonoids in the extracts. However, the result from this study contradicted with the findings by Rafidah et al. (2014), where the TFC in SHS dried avocado pulp increased by 48.6% at the highest temperature of 170 °C. The difference in the result could be due to the difference in the application of SHS as this study only performed pre-treatment with SHS instead of drying technique.

Antioxidant activities

The antioxidant activities of B. pubera extract were determined based on DPPH free radical scavenging activity and FRAP, as displayed in Table 2. The percentage of DPPH scavenging activity of untreated B. pubera of 54.13% was similar to durian kuning (Durio kutejensis), durian tutong and mertajam (Leppisanthes rubiginosa) with 54% scavenging activity, bidara (Ziziphus mauritania) at 57.66%, and mata kucing (Nephellium malaiense) at 56.76% (Ikram et al. 2009).

When treated with SHS, the DPPH radical scavenging activity of B. pubera increased by 23.7% compared to the untreated group. The finding from this study is in agreement with the study by Dewanto et al. (2002), where the thermal processing of sweet corn at 115 °C for 25 min increased the total antioxidant activity significantly by 44%, and the TPC increased by 54% compared to the control sample. The increase in the DPPH scavenging activity of SHS treated B. pubera could be due to the reduction of polyphenols to low molecular weight compounds by the steam (Dewanto et al. 2002; Noda et al. 2013). A study reported that low molecular weight phenolic compounds present in the sample lead to high scavenging activity of DPPH free radicals (Othman et al. 2014). Furthermore, the increase in solubilized flavonoids and the liberation of non-phenolic substances from the cell structure of the fruit owing to thermal processing could also explain the increase in DPPH scavenging activity and total antioxidant activity (Roy et al. 2009). Noda et al. (2013) also stated that degraded polysaccharides and pyrolysis products may also contribute to the antioxidant activity and phenolic compounds.

Zhang et al. (2014) proposed that fruits with higher TPC usually showed stronger antioxidant capacity. A strong positive correlation (R2 = 0.963) was found between the TPC and DPPH of B. pubera. It can be suggested that the polyphenolic compounds in B. pubera extract could be responsible for the scavenging of DPPH free radicals. A similar correlation between TPC and DPPH was also found in a study on some Malaysian herbal plants, where all samples (tenggek burung, kesum, salam, and curry leaves) showed a strong positive correlation between TPC and DPPH (Othman et al. 2014).

In contrast, the antioxidant activity based on the FRAP from the FRAP assay was lower in the SHS treated B. pubera than the untreated B. pubera. This finding is similar to the result of the TFC described earlier. The decrease in flavonoids content in the SHST B. pubera might have led to a decrease in the FRAP activity. This finding is further supported by the strong positive correlation (R2 = 0.935) between the TFC and FRAP assay. In a study by Wojdyło et al. (2016), high antioxidant power occurs due to the presence of flavonoids, such as flavan-3-ols and flavonols. Flavonoids are strong reducing agents. These compounds might have reduced iron (III) to iron (II), hence resulting in an increase in antioxidant activity. Thus, in this study, SHS treatment affects the flavonoids content in B. pubera.

Lycopene

A small amount of lycopene was discovered in B. pubera (0.16 µg/100 g fresh sample). In the extracted samples, SHS treatment reduced the lycopene content by 28.6%. The high amount of trans-lycopene decreased in lycopene standard when the sample was heated at 150 °C, and no lycopene was detected after 10 min of treatment (Lee and Chen 2002). A significant loss of lycopene in dried tomato was observed when dried at 110 °C in the production of tomato puree (Takeoka et al. 2001). Despite the negative results of heat processing on lycopene pigments, thermal treatment resulted in more stable processed tomato with increased bioavailability of lycopene (Dewanto et al. 2002). The difference in the results, whether heat treatment can increase or decrease lycopene content, could be influenced by the difference in food matrices (Benlloch-Tinoco et al. 2015). The decrease in the lycopene content in a heat-treated food sample could be due to the effect of thermal degradation of pigments (Benlloch-Tinoco et al. 2015). The application of heat treatment supports the isomerization of lycopene, from the all-trans-lycopene to cis-lycopene. The ingestion of cis-lycopene may ease its absorption into the lymphatic system compared to its trans-form (Heredia et al. 2010). Therefore, cis-lycopene is more favorable than its trans-form. However, an increase in temperature and prolonged heating time can cause a higher degradation rate of lycopene than isomerization (Lee and Chen 2002). Temperature higher than 100 °C and longer exposure time to heat lead to greater degradation of lycopene content (Fanie 2008). It is suggested that high temperature breaks the molecules into smaller fractions (Fanie 2008). The SHS temperature of 170 °C might have degraded the lycopene in the SHS treated B. pubera extract in this study.

Mineral content

The content of minerals involving phosphorus (P), potassium (K), calcium (Ca), sodium (Na), zinc (Zn), magnesium (Mg), iron (Fe), and copper (Cu) elements was determined and the effect of SHS treatment was evaluated. As shown in Table 3, the content of P and K were the highest in the fruit, with P being the major element (95.5%). Fe and Cu were the least in the fruit content. Phosphorus is a macromineral that is required with calcium for healthy bones and tooth structure, the structure of cell membranes throughout the body, and energy metabolism. Phosphorus has very low toxicity. Meanwhile, iron and copper are trace minerals needed by the human body in a very small amount (British Nutrition Foundation 2019).

Table 3.

Mineral composition of untreated and SHST B. pubera extracts

Elements (mg/100 g edible portion) Untreated SHST
Phosphorus 763.68 ± 1.7019a 515.07 ± 3.2971b
Potassium 26.10 ± 0.0945a 21.34 ± 0.0946b
Calcium 2.87 ± 0.0319a 1.48 ± 0.0120b
Sodium 2.71 ± 0.0453a 1.30 ± 0.0167b
Zinc 2.48 ± 0.0177a 2.39 ± 0.0088b
Magnesium 1.80 ± 0.0152a 1.40 ± 0.0102b
Copper 0.16 ± 0.0014a 0.08 ± 0.0004b
Iron 0.09 ± 0.0039a 0.06 ± 0.0009b
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Data were expressed as mean ± standard deviation (n = 3). The values in different columns with different letters indicate significant difference at p < 0.05 between untreated and SHST B. pubera extracts

The SHS treatment affected the mineral content of B. pubera. The mineral content decreased for all elements, ranging from 3.63 to 52.03%. The lowest decrease in percentage was observed in Zn (3.63%), followed by K (18.24%), Mg (22.22%), P (32.55%), Fe (33.33%), Ca (48.43%), Cu (50%), and Na (52.03%). Cooking with a microwave oven also reduced the mineral content of mustard leaves (Sinapis alba) (Lima et al. 2019). The stability of minerals depends on the exposure to heat and air, the origin of food, and particle size (Akhtar et al. 2009). Morales-de la Peña et al. (2011) suggested that the severity of heat treatment may have modified the mineral content in foods.

Conclusion

This study provides data on the physicochemical properties of B. pubera. The results showed that B. pubera is an acidic fruit with a small amount of lycopene. This underutilized fruit is also found to be a good source of antioxidants. The TPC, TFC, and antioxidant activity of the fruit are comparable to other fruits. This study showed that SHS treatment might enhance the antioxidant activity of B. pubera by increasing the TPC in the fruit. The positive correlation between TPC and DPPH concluded that polyphenols could be the compounds contributing to the free radical scavenging activity. It is proposed that SHS treatment on fruits needs to be conducted at lower temperature and/or lower pressure in future studies to prevent degradation of flavonoids or other volatile compounds.

Acknowledgements

The authors would like to thank Prof. Dato’ Dr. Mohd. Ali Hassan for the facilities, and Dr. Ahmad Muhaimin Roslan for the technical support of the superheated steam treatment at the Biomass Technology Centre, Universiti Putra Malaysia, Serdang, Selangor, Malaysia. Funding was provided by Universiti Teknologi MARA.

Footnotes

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References

  1. Ahmed IA, Maryam AM, Muhammad I, Norazlanshah H, Mohammad SBAR, Radiah AG, Ridhwan AW, Solachuddin JA, Mohammad NAY. Antioxidant activity and phenolic profile of various morphological parts of underutilised Baccaurea angulata fruit. J Food Chem. 2015;172:778–787. doi: 10.1016/j.foodchem.2014.09.122. [DOI] [PubMed] [Google Scholar]
  2. Akhtar S, Anjumet FM, Rehman S-U, Sheik MA. Effect of storage and baking on mineral contents of fortifies whole wheat flour. J Food Process Preserv. 2009;34:335–349. doi: 10.1111/j.1745-4549.2009.00405.x. [DOI] [Google Scholar]
  3. Amiri-Rigi A, Abbasi S. Microemulsion-based lycopene extraction: effect of surfactants, co-surfactants and pre-treatments. Food Chem. 2016;197:1002–1009. doi: 10.1016/j.foodchem.2015.11.077. [DOI] [PubMed] [Google Scholar]
  4. Benlloch-Tinoco M, Kaulmann A, Corte-Real J, Rodrigo D, Martínez-Navarrete N, Bohn T. Chlorophylls and carotenoids of kiwifruit puree are affected similarly or less by microwave than by conventional heat processing and storage. Food Chem. 2015;187:254–262. doi: 10.1016/j.foodchem.2015.04.052. [DOI] [PubMed] [Google Scholar]
  5. Benzie IF, Strain JJ. The Ferric Reducing Ability of Plasma (FRAP) as a measure of “antioxidant power”: the FRAP assay. Anal Biochem. 1996;239(1):70–76. doi: 10.1006/abio.1996.0292. [DOI] [PubMed] [Google Scholar]
  6. British Nutrition Foundation (2019) Minerals and trace elements–British Nutrition Foundation—Page #1. Retrieved February 13, 2019, from https://www.nutrition.org.uk/nutritionscience/nutrients-food-and-ingredients/minerals-and-trace-elements.html?limit=1&start=4
  7. Dewanto V, Wu X, Adom KK, Liu RH. Thermal processing enhances the nutritional value of tomatoes by increasing total antioxidant activity. J Agric Food Chem. 2002;50:3010–3014. doi: 10.1021/jf0115589. [DOI] [PubMed] [Google Scholar]
  8. Djeridane A, Yousfi M, Nadjemi B, Boutassouna D, Stocker P, Vidal N. Antioxidant activity of some algerian medicinal plants extracts containing phenolic compounds. Food Chem. 2006;97(4):654–660. doi: 10.1016/j.foodchem.2005.04.028. [DOI] [Google Scholar]
  9. Fanie M. Stability of lycopene during processing and storage. Food Ingred Bras. 2008;5:32–42. [Google Scholar]
  10. Harris S, Brunton N, Tiwari U, Cummins E. Human exposure modelling of quercetin in onions (Allium Cepa L.) following thermal processing. Food Chem. 2015;187:135–139. doi: 10.1016/j.foodchem.2015.04.035. [DOI] [PubMed] [Google Scholar]
  11. Heredia A, Peinado I, Rosa E, Andrés A. Effect of osmotic pre-treatment and microwave heating on lycopene degradation and isomerization in cherry tomato. Food Chem. 2010;123(1):92–98. doi: 10.1016/j.foodchem.2010.04.005. [DOI] [Google Scholar]
  12. Hoe VB, Siong KH. The nutritional value of indigenous fruits and vegetables in Sarawak. Asia Pac J Clin Nutr. 1999;8(1):24–31. doi: 10.1046/j.1440-6047.1999.00046.x. [DOI] [PubMed] [Google Scholar]
  13. Huang YC, Chang YH, Shao YY. Effects of genotype and treatment on the antioxidant activity of sweet potato in Taiwan. Food Chem. 2006;98:529–538. doi: 10.1016/j.foodchem.2005.05.083. [DOI] [Google Scholar]
  14. Ikram EHK, Khoo HE, Jalil AMM, Ismail A, Idris S, Azlan A, Nazri HSM, Diton NAM, Mokhtar RAM. Antioxidant capacity and total phenolic content of malaysian underutilized fruits. J Food Compos Anal. 2009;22:388–393. doi: 10.1016/j.jfca.2009.04.001. [DOI] [Google Scholar]
  15. Jamil MS, Nadeem R, Hanif MA, Ali MA, Akhtar K. Proximate composition and mineral profile of eight different unstudied date (Phoenix Dactylifera L.) varieties from Pakistan. Afr J Biotech. 2010;9(22):3252–3259. [Google Scholar]
  16. Kahoun D, Řezková S, Královský J. Effect of heat treatment and storage conditions on mead composition. Food Chem. 2016;219:357–363. doi: 10.1016/j.foodchem.2016.09.161. [DOI] [PubMed] [Google Scholar]
  17. Kumaravel S, Alagusundaram K. Determination of mineral content in Indian spices by ICP-OES. Orient J Chem. 2014;30(2):631–636. doi: 10.13005/ojc/300231. [DOI] [Google Scholar]
  18. Lee MT, Chen BH. Stability of lycopene during heating and illumination in a model system. Food Chem. 2002;78(4):425–432. doi: 10.1016/S0308-8146(02)00146-2. [DOI] [Google Scholar]
  19. Lima AMS, dos Santos LO, David JM, Ferreira SLC. Mineral content in mustard leaves according to the cooking method. Food Chem. 2019;273:172–177. doi: 10.1016/j.foodchem.2017.12.042. [DOI] [PubMed] [Google Scholar]
  20. Lombard K, Peffley E, Geoffriau E, Thompson L, Herring A. Quercetin in onion (Allium Cepa L.) after heat-treatment simulating home preparation. J Food Compos Anal. 2005;18(6):571–581. doi: 10.1016/j.jfca.2004.03.027. [DOI] [Google Scholar]
  21. Morales-de La Peña M, Salvia-Trujillo L, Rojas-Graü MA, Martín-Belloso O. Changes on phenolic and carotenoid composition of high intensity pulsed electric field and thermally treated fruit juice-soymilk beverages during refrigerated storage. Food Chem. 2011;129(3):982–990. doi: 10.1016/j.foodchem.2011.05.058. [DOI] [PubMed] [Google Scholar]
  22. Noda Y, Asada C, Sasaki C, Hashimoto S, Nakamura Y. Extraction method for increasing antioxidant activity of raw garlic using steam explosion. Biochem Eng J. 2013;73:1–4. doi: 10.1016/j.bej.2013.01.013. [DOI] [Google Scholar]
  23. Oboh G. Effect of blanching on the antioxidant properties of some tropical green leafy vegetables. Lebensmittel-Wissenschaftund-Technologie—Food Sci Technol. 2005;38(5):513–517. doi: 10.1016/j.lwt.2004.07.007. [DOI] [Google Scholar]
  24. Othman A, Mukhtar NJ, Ismail NS, Chang SK. Phenolics, flavonoids content and antioxidant activities of 4 Malaysian herbal plants. Int Food Res J. 2014;21(2):759–766. [Google Scholar]
  25. Prommuak C, De-Eknamkul W, Shotipruk A. Extraction of flavonoids and carotenoids from Thai silk waste and antioxidant activity of extracts. Sep Purif Technol. 2008;62(2):444–448. doi: 10.1016/j.seppur.2008.02.020. [DOI] [Google Scholar]
  26. Rafidah H, Ando Y, Amin I, Shirai Y, Mohd Ali H. Enhanced polyphenol content and antioxidant capacity in the edible portion of avocado dried with superheated-steam. Int J Adv Res. 2014;8(2014):241–248. [Google Scholar]
  27. Rao AV, Rao LG. Carotenoids and human health. Pharmacol Res. 2007;55(3):207–216. doi: 10.1016/j.phrs.2007.01.012. [DOI] [PubMed] [Google Scholar]
  28. Roy MK, Juneja LR, Isobe S, Tsushida T. Steam processed broccoli (Brassica Oleracea) has higher antioxidant activity in chemical and cellular assay systems. Food Chem. 2009;114(1):263–269. doi: 10.1016/j.foodchem.2008.09.050. [DOI] [Google Scholar]
  29. Sehrawat R, Nema PK, Kaur BP. Quality evaluation and drying characteristics of mango cubes dried using low-pressure superheated steam, vacuum and hot air drying methods. Lebensmittel-Wissenschaftund-Technologie—Food Sci Technol. 2018;92:548–555. doi: 10.1016/j.lwt.2018.03.012. [DOI] [Google Scholar]
  30. Shakirin FH, Prasad KN, Ismail A, Lau CY, Azlan A. Antioxidant capacity of underutilized Malaysian Canarium Odontophyllum (Dabai) Miq. fruit. J Food Compos Anal. 2010;23:777–781. doi: 10.1016/j.jfca.2010.04.008. [DOI] [Google Scholar]
  31. Stamatopoulos K, Katsoyannos E, Chatzilazarou A, Konteles SJ. Improvement of oleuropein extractability by optimising steam blanching process as pre-treatment of olive leaf extraction via response surface methodology. J Food Chem. 2012;133:344–351. doi: 10.1016/j.foodchem.2012.01.038. [DOI] [PubMed] [Google Scholar]
  32. Švarc-Gajić J, Cerdà V, Clavijo S, Suárez R, Mašković P, Cvetanović A, Cristina D-M, Ana PC, Novakov V. Bioactive compounds of sweet and sour cherry stems obtained by subcritical water extraction. J Chem Technol Biotechnol. 2018;93(6):1627–1635. doi: 10.1002/jctb.5532. [DOI] [Google Scholar]
  33. Takeoka GR, Dao L, Flessa S, Gillespie DM, Jewell WT, Huebner B, Ebeler SE. Processing effects on lycopene content and antioxidant activity of tomatoes. J Agric Food Chem. 2001;49(8):3713–3717. doi: 10.1021/jf0102721. [DOI] [PubMed] [Google Scholar]
  34. US Food & Drug Administration (2012) Appendix 3. Factors that affect microbial growth in food. Bad bug book: handbook of foodborne pathogenic microorganisms and natural toxins, vol 2, pp 261–264
  35. Wojdyło A, Carbonell-Barrachina ÁA, Legua P, Hernández F. Phenolic composition, ascorbic acid content, and antioxidant capacity of Spanish jujube (Ziziphus jujube Mill.) fruits. Food Chem. 2016;201:307–314. doi: 10.1016/j.foodchem.2016.01.090. [DOI] [PubMed] [Google Scholar]
  36. Zhang Y, Sun Y, Xi W, Shen Y, Qiao L, Zhong L, Zhou Z. Phenolic compositions and antioxidant capacities of Chinese wild mandarin (Citrus Reticulata Blanco) fruits. Food Chem. 2014;145:674–680. doi: 10.1016/j.foodchem.2013.08.012. [DOI] [PubMed] [Google Scholar]

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