Production of buns, the bakery-based snack food, with reduced refined wheat flour content: Recent developments

Abstract

Buns are very soft puffed bakery snack items, popular in many countries, especially low- and middle-income nations. Buns are either eaten directly or used in the preparation of culinary items. Buns are mainly prepared using refined wheat flour rich in gluten protein and devoid of husk. Consuming gluten-containing foods is leading to several health complications among consumers worldwide. Hence, several researchers have tried to reduce the gluten content in the dough by incorporating cereals flours, protein-rich sources like soy, cheese whey, etc., hydrocolloids, millets, pomace, and seed flour of vegetables and fruits, etc. These additives not only reduce gluten content in the buns to a certain extent but also enhance the fibre content and nutritional profile of the buns. This mini-review summarizes the recent developments in the production of buns using these additives to improve their nutritional quality.

Introduction

Buns are puffed baked balls made using mainly maida, which contains gluten protein, due to which it gets the typical structure. In many countries, buns are considered a poor man’s diet. Compared with any other baked food product, it is priced very low. Hence, it is affordable for many low-income populations. Buns are consumed as a snack food along with hot beverages, mainly tea. Buns are of three types, i.e., plain buns, sweet buns, and spicy buns. There are varieties of buns like hamburger buns (consumed with savoury fillings), hot dog buns, yeast bread, etc. (Fig. 1). In general, sweet buns and spice buns are eaten directly either with tea or coffee, whereas, plain buns are used in sandwich or snack food preparation. The common steps involved in the preparation of sweet buns are depicted in Fig. 2.

Fig. 1.

Different varieties of buns sold in local market

Fig. 2.

Traditional sweet bun-making process. (Information source: https://simpleindianrecipes.com/More/Sweet-Buns.aspx)

Buns with different flavours, such as coconut, chocolate, red bean, potato, and kaya, are manufactured commercially and sold in Malaysia (Norizan et al. 2018). Buns are a source of nutrients and energy. However, regular consumption of buns may lead to health complications like constipation, etc., as the main ingredient used in the production of buns (refined wheat flour, also known as maida, which is the endosperm devoid of germ and fibre (out layer/bran) of the wheat) is not good for health on the long run. Removing the bran and germ decreases the nutritional quality and fibre content of the wheat, and the chemical used to make it whiter (benzoyl peroxide) is banned in many countries due to its impact on the health of the consumers.

The dark side of the maida has been reviewed recently (Gowri et al. 2015; Ganga et al. 2020). The maida can bind to the intestinal lining and prevent nutrient absorption from the digested food (Anon 2022). The glycaemic index of the maida is higher than wheat. Maida is digested faster than wheat. Regular consumption of maida can lead to diabetes due to the quick release of sugar. Eating maida-containing foods in fried form is even more harmful. The body's metabolic rate can be disrupted by it, and it may lead to Alzheimer’s disease, heart disease, kidney stone formation, increased bad cholesterol (LDL), arthritis, and even cancer (Anon 2016, 2021, 2022). Maida can increase the craving for sweets and cause digestive disturbances. It can keep people hungry and lead to constipation, inflammation, insulin resistance, and health and nutritional disorders like appendicitis, diverticulum, ischaemic heart diseases, etc. Thus, regular consumption of gluten-containing products can ruin consumers' health. Hence, researchers are trying to develop new formulations for the preparation of gluten-free bakery products and buns in particular.

Gluten is an essential component in formulating any leavened baked product. The gluten protein, which is insoluble in 0.5% sodium chloride or water and provides visco-elastic structure to bakery products, present in buns and other bakery products can cause several health complications such as dermatitis herpetiformis, coeliac disease, non-coeliac gluten sensitivity, gluten ataxia, etc., if consumed on a regular basis. Ingestion of gluten can lead to mucosal damage and inflammation in the epithelium of the small intestine in people with celiac disease and it may lead to malabsorption of minerals like calcium, iron, vitamins folic acid and fat-soluble vitamins (Catassi and Fasano 2008) causing anaemia, osteoporosis, skin diseases, etc. (Pruska-Kędzior et al. 2008).

As gluten intolerance is growing globally, researchers are focusing on the production of gluten-free alternate bakery products. However, ensuring the stability and elasticity of such products is very important to receive customer acceptance. A recent survey has indicated that 70.80% of the consumers who participated in the survey are not satisfied with gluten-free bread due to the change in taste and texture of gluten-free bakery products (Toth et al. 2020). The crumb of gluten-free bread usually hardens faster than the crumb of gluten-containing bread. In addition, gluten-free baker products tend to stale rapidly. Segura and Rosell (2011) have determined the starch digestibility of gluten-free bread in vitro using commercially available α-amylase from porcine pancreas and amyloglucosidase (EC 3.2.1.3.) and found 75–92% of the predominant fraction of the starch was rapidly digestible. A recently published review summarized research carried out on starch digestibility and its impact on human health, besides detailing the methods to produce resistant starches and their impact on the gut microbiome (Bello-Perez et al. 2020). Additives like hydrocolloids, sugars, sugar alcohols, lipids, proteins, polypeptides, amino acids, polyphenols and various processes like heat-moisture treatment, annealing, high-hydrostatic pressure treatment, esterification, extrusion, etc., could reduce starch digestibility and improve shelf stability (Mohamed 2021). These food additives and ingredients help decrease starch digestibility by hindering the contact between starch and digestive enzymes or inhibiting the activity of digestive enzymes themselves (Yang et al. 2023). Hence, the addition of these compounds in buns preparation could help retard starch digestion and minimize health complications like accumulation of glucose in plasma and hyperinsulinemia. Therefore, the present mini-review aimed at consolidating the research carried out in the production of buns to reduce the maida content and to improve the nutritional quality of the buns.

Recent developments in buns production

Aiming to enhance nutritional quality and reduce the health risks of consuming bakery products containing gluten, several researchers have tried to produce buns either devoid of maida or supplementing maida with other flours so that the amount of maida is reduced to a certain extent in the buns and to improve the nutritional quality of the buns and it is summarized in Table 1.

Table 1.

Recent developments to increase the nutritional and textural quality of buns

Type of supplementation	Improvement targeted	References
Cereals-rich buns
Starch, rice flour and corn flour	Reducing gluten content	Angelica (2018)
De-oiled maize germ flour	Reducing gluten content, texture improvement	Arora and Saini (2016)
Buckwheat and buckwheat sprouts	Enhanced flavonoids and total phenols	Sturza et al. (2020)
Protein-rich buns
Defatted soy flour	Enhanced protein and mineral content	Tsen et al. (1976)
Defatted soybean meal	Enhanced protein content	Indrani et al. (1997)
Lactose hydrolysed concentrated paneer whey	Enhanced protein and mineral content	Reddy et al. (2016)
Germinated horse gram	Enhanced protein and mineral content	Bhokre et al. (2012)
Edible winged termites’ flour	Enhanced protein, riboflavin, retinol, zinc and iron content	Kinyuru et al. (2009)
Cricket (insect) flour		Alemu et al. (2017)
Vegetables and fruits
Carrot pomace powder	Increased the fibre and vitamin content	Kumar and Kumar (2012)
Carrot pomace and pineapple pomace	Increased fibre and other nutrients	Badjona et al. (2019)
Apple and orange pomace, pepper peel, tomato peel, prickly pear peel and its seed peel	Increased dough height, specific volume, CO2 retention coefficient and the total CO2 production	Djeghim et al. (2021)
Blue berries	Improved nutrition	Gould (2003)
Purple sweet potato flour	Improved physicochemical and sensory characteristics	Aritonang and Julianti (2020)
Jackfruit seeds flour (potassium, calcium, phosphorus and magnesium) content	High protein, ash, fibre and minerals	Ngwere and Mongi (2021)
Mashed fresh Orange-fleshed sweet potato	Increased β-carotene and vitamin A	Low and van Jaarsveld (2008)
Anne green leaves (Celosta argentea)	Increased micronutrients and fibre content	Pattan and Usha Devi (2014)
Millets supplemented buns
Finger millets (Eleusine coracana) flour serum LDL, serum triglycerides, VLDL and increased HDL cholesterol	Reduced fasting blood glucose, post prandial blood glucose, serum cholesterol,	Tiwari and Srivastava (2017)
Brans of proso millets and barnyard millets	Increased fibre and nutritional content	Barbhai et al. (2020)
Foxtail and kodo millet bran rich fractions	50% less in available carbohydrates and the glycemic index of 57.71%	Barbhai et al. (2021)
Finger millet flour and 7.5% of moringa leaf powder	Improved fibre content and nutritional quality of Burger buns	Boria et al. (2021)
Hydrocolloids and other additives
5% psyllium husk	Softening the bun texture	Abdullah et al. (2021)
Oleogels of olive oil and sunflower oil prepared using xanthan gum and HPMC	Reduced saturated and trans-fatty acids	Bascuas et al. (2021)
Lactic fermentation of hemp, quinoa, and chia flour	Increased porosity in gluten-free sourdough prepared using corn or rice	Jagelaviciute and Cizeikiene (2021)
10% fenugreek seed powder	Reduced blood glucose levels	Robert et al. (2016)
Chocolate, coconut powder, red bean flour, potato flour, kaya bean flour	Increased vitamin-C content and poly unsaturated fatty acids in commercial bun	Norizan et al. (2018)

HPMC hydroxy propyl methyl cellulose

Addition of cereals

To reduce gluten content in bakery products, several researchers have tried to use cereals and pseudocereals while preparing bakery products. Rice, corn, teff, sorghum, Job’s tears are gluten-free cereals, and buckwheat, amaranth, and quinoa are examples of pseudocereals. In this context, a very recent review has focused on technology for the production of gluten-free bread and other bakery products (Šmídová and Rysová 2022). Certain cereals grains like wheat, barley, and rye contain gluten up to 70–80%. The composition of gluten-free bakery products, like protein content, fat content, and fibre content, including the buns, varies depending on the ingredients used to make them. Accordingly, its energy values also change. The fibre, which is absent in gluten proteins, not only provides health benefits but also improves apparent viscosity, texture, consistency, specific volume, sensory properties, and shelf life due to its water-binding ability.

With an aim to provide a gluten-free diet for celiac disease patients, buns with vanilla flavour were prepared using starch, rice flour, and cornflour in a ratio of 20:40:40, and it is free from sugars (Angelica 2018). Arora and Saini (2016) have prepared buns using wheat flour added with different levels of de-oiled maize germ flour (5, 10, 15, 20, and 25%). They observed a decrease in loaf volume with an increase in germ flour and an increase in yield with an increase in germ flour. However, the buns made supplementing 10% of de-oiled maize germ to wheat flour received the highest overall score in appearance.

Sturza et al. (2020) have determined the influence of flours of buckwheat and buckwheat sprouts on the nutritional and textural quality of wheat buns. Buns prepared using the wheat dough added with 20% buckwheat or 10% sprouts flour could get 9.1 and 8.7 points in the sensory score, respectively, besides improving the nutritional value of the buns in terms of flavonoids enhancement by around 26% and total phenols nearly 2.5 times.

Protein-rich buns

Legumes such as bean, chickpea, pea, lentil, and lupine flours are also added to the gluten-free dough to increase the protein content in the buns or bakery products. While adding the protein-containing resources, the maida content is reduced to make it healthier and more nutritious (Foschia et al. 2017; Melini et al. 2017). The protein content in the buns can be enhanced by supplementing the dough with protein-rich sources like soybean flour, whey protein concentrates, insect protein, etc. Fortification of wheat flour with 12% defatted soy flour enhanced protein and minerals content by 27.5% and 29.2%, respectively, in hot dog buns (Tsen et al. 1976). Similarly, the addition of defatted soybean meal at 15% in wheat flour enhanced the protein content in the buns from 11 to 18.89% (Indrani et al. 1997). The addition of germinated horse gram at 10% to refined wheat flour has improved protein and mineral content in buns with acceptable sensory quality (Bhokre et al. 2012).

Crumb hardness is reduced by 30–65% with the addition of 1% of flax (Linum usitatissimum) seed or acacia seed powders in gluten-free bread (Krishna et al. 2019). Fermentation of dough with lactic acid bacteria (LAB) can improve its rheological properties due to the production of exopolysaccharides (Ketabi et al. 2008). The addition of emulsifiers like egg yolk, milk, soy protein, lupin, or sunflower flour, can soften the crumb. Similarly, supplementation of gluten-free dough with hydrocolloids like HPMC, CMC, carrageenans, agar, guar gum, gum Arabic, locust bean gum, konjac gum, tara gum, psyllium, xanthan, etc., can hydrate the dough and enhance water binding and swelling properties of the dough and results in low volume of the bread (Abdullah et al. 2021; Belorio and Gómez 2020; Liu et al. 2018; Morreale et al. 2018; Anton and Artfield 2008; Culetu et al. 2021). However, texture, rheology, and other properties of dough differ slightly based on the hydrocolloid used. The addition of guar gum, carrageenan and xanthan decreased dough extensibility, and HPMC and Arabic gum increased extensibility (Salehi 2019).

The use of lactose hydrolysed concentrated paneer whey, which is rich in proteins and minerals, containing 20% total solids and 25% wheat flour, was envisaged to prepare good quality buns and these buns had a shelf life of 4 days at 30 °C (Reddy et al. 2016). The addition of proteins to the gluten-free dough also enhances the nutritional quality of bakery products. These proteins may be from microorganisms (single-cell proteins), animal sources (egg, whey, casein, etc.), insect sources, algae, plant sources (soy, legumes, sunflower, canola, potato, and gluten-free cereals), and seaweeds (Skendi et al. 2021). These proteins by interacting with lipids and starch, stabilize the dough and provide structure to the bakery products.

Wheat buns were also prepared, incorporating edible winged termites to enhance nutritional quality (Macrotermes subhylanus) in Kenya (Kinyuru et al. 2009). Substitution of wheat with 5% dried ground termites significantly increased the protein, riboflavin, retinol, zinc, and iron to the extent of 16–53%. It was well accepted in sensory evaluation with scores above 5.0. In Kenya, people prefer to eat buns incorporated with 5% cricket (insect) flour rather than buns without cricket flour or 10% cricket flour supplementation (Alemu et al. 2017).

Addition of vegetables and fruit pomace

To make the buns more nutritious and easily digestible, the addition of substances rich in dietary fibre, minerals, phytochemicals, etc., has been tried. To achieve this, several researchers have used pomace of vegetables and fruits. Carrot pomace is a rich source of dietary fibre, antioxidants, and carotenes. Hence, Kumar and Kumar (2012) have increased the fibre and vitamin content of wheat flour-based buns by incorporating carrot pomace powder, and buns made from wheat flour added with a 2.5% level of carrot pomace powder got a higher sensory score than with other levels (5% 7.5% and 10%). However, the linear and surface expansion values were found to decrease in these buns more than in the control buns made devoid of carrot pomace. In another study, the addition of carrot pomace at 15% and pineapple pomace at 5% to wheat flour resulted in sensorially accepted rock buns with improved content of ash, beta carotene, and crude fibre (Badjona et al. 2019).

Djeghim et al. (2021) found significant improvement in a specific volume of gluten-free bread and increased dough height, CO₂ retention coefficient, and the total CO₂ production with the addition of various by-products like apple and orange pomace, pepper peel, tomato peel, prickly pear peel, and its seed peel, etc., to corn and chickpea flours containing dough. Blueberry buns, which are six inches long, three inches wide, and oval in shape, are popular in Toronto, Canada (Gould 2003). Blueberries are placed in the dough, and the dough is coated with egg white and large sugar crystals before backing. Pattan and Usha Devi (2014) have explored using dehydrated unconventional green leafy vegetable (Anne green, Celosia argentea), which is rich in micronutrients, for the preparation of masala (spicy) buns and the addition of dehydrated green powder at 6% resulted in better acceptance in sensory analysis.

The addition of curry leaves (Murraya koeniggi) and coriander leaves (Coriandrum sativum) in the ratio of 1:1 to a blend of whole wheat flour and refined wheat flour have increased dietary fiber, protein, carotenoids, and iron content in buns and thus improved overall nutritional status of the buns (Sudha et al. 2014).

The sweet buns prepared using 60% of wheat flour and 40% of purple sweet potato flour were found to be the most acceptable by consumers in terms of best physicochemical and sensory characteristics (Aritonang and Julianti 2020). Jackfruit seeds flour, which is rich in nutrients, was incorporated into the whole wheat flour at 10% for the production of nutrient-dense composite flour buns that had higher levels of protein, ash, fibre, and minerals (potassium, calcium, phosphorus, and magnesium) than whole wheat buns made without jackfruit seed flour supplementation (Ngwere and Mongi 2021).

In another study, 38% of the wheat flour was replaced with mashed fresh Orange-fleshed sweet potato to increase the β-carotene content of the buns (Low and van Jaarsveld 2008). These buns had an attractive appearance and heavier texture than buns made using wheat flour alone. Depending on the variety of sweet potatoes, they had 774 to 969 μg/60 g bun of trans-β-carotene and 61 to 85 μg RAE of Vitamin A per 60 g bun.

Addition of millet flours

Nowadays, the use of millets is picking up due to the health consciousness of the people. Thus, researchers started using different millet flours in the preparation of bakery products and, in particular, buns to replace maida partially or fully. Gluten-free products tend to have low nutritional quality with poor crumb and crust development characteristics, besides fast staling. In this direction, Tiwari and Srivastava (2017) have prepared buns using 60% wheat flour and 40% finger millet (Eleusine coracana) flour. Consuming finger millet-containing buns (200 g/day) for 60 days could reduce fasting blood glucose by 13.75%, postprandial blood glucose by 14.43%, serum cholesterol by 4.41%, and serum LDL by 11.22%, serum triglycerides by 5.11%, VLDL by 4.74% and increased the HDL cholesterol significantly by 14.98%.

Cereal brands are a rich source of phytonutrients (flavonoids, phenols), nutrients, and dietary fibre. With the intention of increasing the fibre and nutritional content, brans of minor millets, proso millets, and barnyard millets were incorporated in refined wheat flour (maida) at various levels (0–30%) to prepare buns and muffins (Barbhai et al. 2020). Though the water absorption capacity of dough was increased with the incorporation of these brans, foaming capacity, water solubility index, and oil absorption rate decreased. Buns added with 20% barnyard and proso millets bran had better acceptability without significantly affecting the sensory quality of the buns. The same authors have also studied the effect of foxtail and Kodo millet BRF on the quality of buns and muffins (Barbhai et al. 2021). These buns had nearly 50% less in available carbohydrates, and the GI was 57.71%. Buns prepared with 20% foxtail BRF had better acceptability. However, they had only three days of shelf life at room temperature. Burger buns were prepared with the fortification of refined wheat flour with 10% of ragi (finger millet) flour and 7.5% of moringa leaf powder (Boria et al. 2021).

Use of hydrocolloids in buns

Researchers have tried to use hydrocolloids as additives while formulating the bakery products to improve the texture and overall quality of the gluten-free bakery products and to retard digestibility. The addition of 5% psyllium husk to white wheat flour significantly softened the bun texture and had the lowest compression force value of 4.03 ± 0.12 N, whereas, the addition of 5% psyllium husk to whole wheat flour resulted in a much harder texture (7.37 ± 0.16 N) of the bun (Abdullah et al. 2021). To reduce the negative impact of margarine and shortenings, which are rich in saturated and trans-fatty acids, on consumers' health, hydrocolloids like xanthan gum and HPMC were used to prepare oleogels olive oil and sunflower oil as a substitute for margarine in steamed buns and other bakery products (Bascuas et al. 2021). The addition of 2% xanthan gum in rice bread suppressed starch digestion from 79.8 to 57.3% and this effect was diminished when added in combination with 20% gluten, however, it led to a significant reduction in the porosity, loaf volume and sticker structure of rice bread crumbs (Sasaki 2022).

Use of in-situ exopolysaccharide (dextran, fructan, levan, reuteran, etc.) producing LAB for dough fermentation could improve the gluten-free dough rheology by way of enhancing the porosity, reducing the hardness of the crumb, besides slowing down the staling (Deora et al. 2014; Capelli et al. 2020). Jagelaviciute and Cizeikiene (2021) have used Lactobacillus sanfranciscensis to ferment hemp, quinoa, and chia flour to increase porosity non-traditional gluten-free sourdough prepared with corn or rice. The use of sourdough in gluten-free bakery products also delayed fungal spoilage and extended the shelf life (Ramos et al. 2021).

Buns for improved health

Buns incorporated with 10% fenugreek seed powder were prepared with the aim of reducing blood glucose levels (Robert et al. 2016). These buns could reduce GI and glycemic response. Reducing sucrose content by 30% in wheat starch flour improved fermentation with increased gas formation than in control burger buns (Sahin et al. 2017). It also helps in reducing obesity.

Foong and Mahat (2020) analysed commercially prepared sweet buns with the incorporation of kaya, potato, chocolate, coconut, and red bean for nutritional quality using the technique for order of preference by similarity to ideal solution (TOPSIS), a mathematical technique. Out of all varieties studied, the highest value of relative closeness to the ideal solution of 0.738 was observed for the chocolate bun, followed by red bun (0.640), coconut (0.551), Kaya (0.439), and potato (0.372), indicating that chocolate bun has the best nutrient contents and the potato bun has the least non-benefit nutrient contents. This study also confirms the earlier observation that consuming dark chocolates can reduce oxidative-stress markers (Allgrove et al. 2011).

Vitamin-C content was the highest (4.25 mg/100 g) in chocolate buns, followed by coconut buns (3.48 mg/100 g), red bean buns (2.97 mg/100 g), potato buns (2.85 mg/100 g), and kaya buns (2.07 mg/100 g) sold in Malaysia (Norizan et al. 2018). Among all these buns, the short-chain fatty acid content was the lowest in the kaya bun (1.70 g/100 g), and in all other buns, it is in the range of 3.30 to 4.85 g/ 100 g, whereas, the higher content of polyunsaturated fatty acids (0.83–0.85 g/100 g) was noticed in potato buns and red bean buns. The cholesterol content in all these buns was in the range of 0.53 to 24.90 mg/100 g, and the highest was in potato buns.

Future scope

Bakery products are the preferred and convenient food items for a majority of the population, especially during breakfast and on the move. However, consuming bakery products like buns containing gluten on a regular basis poses increased health risks to consumers. It led to the production of gluten-free bakery products by incorporating several food substances like cereal flour and flour from root vegetables, pomace from vegetables and fruits, milled flour, etc. However, these products are not 100% gluten-free products. In addition, not all millets have been tried to make buns. Hence, further research and development are needed to produce bakery products completely devoid of gluten without affecting the texture and key quality parameters that are essential for bakery products. Production of organic buns using all organic components like sugar, butter, flour, and other additives is another area that many researchers did not cover. In view of the growing consumers' demand for organic foods, it needs to be explored as the global bun and bakery market is expanding rapidly. More focus on using whole grain flour for buns production is the need of the hour to reduce health complications developed by bakery products.

Abbreviations

BRF

Bran-rich fractions

CMC

Carboxy methyl cellulose

GI

Glycemic index

HDL

High-density lipoproteins

HPMC

Hydroxy propyl methyl cellulose

LDL

Low-density lipoproteins

RAE

Retinol activity equivalents

VLDL

Very-low-density lipoprotein

Authors' contributions

SVN conceptualized the theme of the review, collected published literature, drafted and reviewed the submission. RS has collected the published literature and formatted the review.

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Authors declare: no conflict of interest.

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