Physicochemical properties, protein and starch digestibility of lentil based noodle prepared by using extrusion processing

A comprehensive review of processing, functionality, and potential applications of lentil proteins in the food industry

There is a pressing need for sustainable sources of proteins to address the escalating food demands of the expanding global population, without damaging the environment. Lentil proteins offer a more sustainable alternative to animal-derived proteins (such as those from meat, fish, eggs, or milk). They are abundant, affordable, protein rich, nutritious, and functional, which makes them highly appealing as ingredients in the food, personal care, cosmetics, pharmaceutical and other industries. In this article, the chemical composition, nutritional value, and techno-functional properties of lentil proteins are reviewed. Then, recent advances on the extraction, purification, and modification of lentil proteins are summarized. Hurdles to the widespread utilization of lentil proteins in the food industry are highlighted, along with potential strategies to surmount these challenges. Finally, the potential applications of lentil protein in foods and beverages are discussed. The intention of this article is to offer an up-to-date overview of research on lentil proteins, addressing gaps in the knowledge related to their potential nutritional benefits and functional advantages for application within the food industry. This includes exploring the utilization of lentil proteins as nanocarriers for bioactive compounds, emulsifiers, edible inks for 3D food printing, meat analogs, and components of biodegradable packaging.

The role of non-starch constituents in the extrusion processing of slow-digesting starch diets: A review

Starch is the main source of energy for the human body through diet, and its digestive properties are closely related to the occurrence of chronic diseases. Extrusion technology, which is characterized by low cost and high efficiency, has been widely used in the field of reducing starch digestibility and modifying starch, and it has great potential for designing and manufacturing precision nutrition for specific populations. However, this aspect of study has not been systemically summarized, so we systematically discuss the role of extrusion and non-starch components in starch modification in this review. This review focuses on the following sections: the effect mechanisms of extrusion on starch digestibility in terms of granule morphology, crystal structure, viscosity and pasting characteristics; the different effects of single or multiple non-starch components on starch digestibility under extrusion; and some of the current applications of extrusion technology in the development of slow-digesting starchy diets. This review summarises the effects of extrusion techniques and non-starch components on starch digestibility under extrusion conditions, and provides the appropriate theoretical basis for the application of starch-based foods in the development of slow-digesting diets, the precise nutritional design of specific populations, and the improvement of the structure of healthy human diets.

Proximate, structural, textural, sensory and microbiological properties of non-gluten extrudate using Sorghum (Sorghum bicolor L. Moench) and a sprouted legume (Phaseolus lunatus L.)

The inclusion of legumes as functional ingredients in a gluten-free extrusion process has been gaining attention in recent times. In this study, sorghum and germinated lima bean flour (100, 90:10, 80:20, 70:30, 60:40 and 50:50) was extruded (feed moisture - 18%, screw speed - 250 rpm, barrel temperatures 50 °C-120 °C-120 °C, die hole diameter - 3 mm) and analysed for functional, proximate, textural, structural, pasting, microbiological and sensory properties. With 100% sorghum used as control, lima beans addition significantly (p < 0.05) improved the loose (0.37-0.44 g/ml) and packed (0.63-0.72 g/ml) bulk density, while water (5.00-3.15 g/g) and oil (2.45-1.60 g/g) absorption capacity and expansion ratio (3.11-2.30) decreased, respectively. An increase in protein (12.77-18.00%), crude fibre (2.58-5.17%) and ash content (2.11-3.12%) were observed in the extrudate, while the (L*) colour parameter (54.49-43.62), hardness (180.04-78.36 N) and pasting viscosities reduced with addition of lima beans. The structural micrograph depicted air-trapped bubbles with thick walls after adding lima beans, while a notable decline in microbial count below approved limits was observed after 8 weeks of storage. Sensory scores showed that values obtained were above average with the 90:10 sorghum-lima bean ratio having the highest score. The economic and industrial value of underutilised legumes such as lima bean can be promoted as functional ingredients via extrusion in addressing coeliac disease and alternative sources of protein, especially in developing countries.

Development of functional noodles by encapsulating mango peel powder as a source of bioactive compounds

Antioxidant compounds such as phenolics and carotenoids scavenge reactive oxygen species and protect against degenerative diseases such as cancer and cardiovascular disease when used as food additives or supplements. Mango peel is a by-product of mango which is a good source of bioactive substances such as phytochemicals, antioxidants, and dietary fibers. Unfortunately, the study on mango peel as a potential food additive is very limited. Accordingly, the present study aimed to develop functional noodles through extrusion technology with the encapsulation of mango peel powder as a natural source of bioactive compounds. First, mango peel powder (MPP) was prepared and incorporated during the mixing of ingredients before noodles formation at three different levels (2.5, 5 and 7.5 %). Afterward, the noodles were studied to determine how the encapsulated MPP affects the proximate composition, physicochemical characteristics, polyphenols, carotenoids, anthocyanin, antioxidant and antidiabetic activity, and sensory characteristics. The noodles exhibited a dose-dependent relationship in the content of bioactive components and functional activities with the encapsulation of MPP levels. A significantly (p 0.05) higher value was noticed in 7.5 % of MPP-encapsulated noodles than in any level of MPP encapsulation in noodles. The fiber and protein contents in the MPP-encapsulated noodles were increased by about 0-1.22 % and 0-3.16 %, respectively. However, noodles' color index and water absorption index were decreased with the level of MPP encapsulation. The cooking loss of noodles increased from 4.64 to 5.17, 6.49, and 7.32 %, whereas the cooked weight decreased from 35.11 to 34.40, 33.65, and 33.23 % with 2.5, 5.0, and 7.5 % of MPP encapsulation, respectively. However, MPP was stable during storage of noodles exhibiting higher phenolic content and antioxidant activity than control samples. The sensory evaluation showed that MPP-encapsulated noodles at levels 2.5 and 5 % had approximately similar overall acceptability values with the control sample. As a result of the findings, it appears that adding MPP up to 5 % to noodles improves their nutritional quality without changing their cooking, structural, or sensory aspects. Therefore, mango peel powder can be a potential cheap source for the development of functional noodles and food ingredients.

Multiresponse optimization of the extrusion process for ready-to-eat snacks from pineapple byproducts and maize flour

This research aimed to optimize the processing conditions to obtain ready-to-eat extruded snacks with a high fiber content from mixtures of pineapple byproduct powder (PBP) and nixtamalized maize flour (PBP-NMF) or maize flour (PBP-MF). The effects of barrel temperature, feed moisture content, and PBP were evaluated. The increase in barrel temperature has a negative effect on the bulk density, the water absorption index, and the texture in both mixtures (PBP-MF and PBP-NMF) and increases the expansion index and the water solubility index in the mixture with MF. The increase in the feed moisture content increased the bulk density and water absorption index in both mixtures and the texture in the mixtures with MF. The increasing PBP decreases the expansion index and increases the water solubility index in both mixtures. The increase in PBP in the mixtures with MF decreases the water absorption index, texture, and bulk density. From the optimization, four products were obtained, two for the NMF mixture and two for the MF mixtures. The optimal formulations can be considered a good source of total fiber (12.46-12.78 g/100 g) and protein (8.27-8.85 g/100 g) with good acceptance by consumers. PRACTICAL APPLICATION: Pineapple byproducts in combination with nixtamalized and nonnixtamalized maize flour are viable raw materials for the development of ready-to-eat extruded snacks with a high content of dietary fiber and good acceptance by consumers. Due to their characteristic nutritional properties, the consumption of this ready-to-eat snack could present potential benefits for human health.

A review on the hydration properties of dietary fibers derived from food waste and their interactions with other ingredients: opportunities and challenges for their application in the food industry

Dietary fiber (DF) significantly affects the quality attributes of food matrices. Depending on its chemical composition, molecular structure, and degree of hydration, the behavior of DF may differ. Numerous reports confirm that incorporating DF derived from food waste into food products has significant effects on textural, sensory, rheological, and antimicrobial properties. Additionally, the characteristics of DF, modification techniques (chemical, enzymatic, mechanical, thermal), and processing conditions (temperature, pH, ionic strength), as well as the presence of other components, can profoundly affect the functionalities of DF. This review aims to describe the interactions between DF and water, focusing on the effects of free water, freezing-bound water, and unfreezing-bound water on the hydration capacity of both soluble and insoluble DF. The review also explores how the structural, functional, and environmental properties of DF contribute to its hydration capacity. It becomes evident that the interactions between DF and water, and their effects on the rheological properties of food matrices, are complex and multifaceted subjects, offering both opportunities and challenges for further exploration. Utilizing DF extracted from food waste exhibits promise as a sustainable and viable strategy for the food industry to create nutritious and high-value-added products, while concurrently reducing reliance on primary virgin resources.

Factors influencing the starch digestibility of starchy foods: A review

Starchy foods are a major energy source of the human diet, their digestion is closely related to human health. Most foods require lots of processing before eating, therefore, many factors can influence starch digestibility. The factors that affect the digestibility of starches have been widely discussed previously, but the extracted starches in those studies were different from those present within the actual food matrix. This review summarizes the factors influencing the starch digestibility in starchy foods. Endogenous non-starch components hinder the starch digestive process. Food ingredients and additives decrease starch digestibility by inhibiting the activity of digestive enzymes or hindering the contact between starch and enzymes. Storage induce the retrogradation of starch, decreasing the digestibility of foods. Therefore, preparing starchy foods with whole grains, processing them as little as possible, using food additives reasonably, and storage conditions may all be beneficial measures for the production of low GI foods.

Effect of screw speed and die temperature on physicochemical, textural, and morphological properties of soy protein isolate-based textured vegetable protein produced via a low-moisture extrusion

In this study, textured vegetable protein (TVP) based on soy protein isolate, wheat gluten, and corn starch was prepared at a 5:3:2 (w/w) ratio using a low-moisture extrusion process. To evaluate the effects of extrusion parameters, die temperature and screw rotation speed, on the properties of TVP, these two parameters were manipulated at a constant barrel temperature and moisture content. The results indicated that increasing the die temperature increased the expansion ratio while decreasing the density of the extrudates. Simultaneously, increasing the screw rotation speed clearly increased the specific mechanical energy of the TVP. Furthermore, mathematical modelling suggested that the expansion ratio increases exponentially to the die temperature. However, extreme process conditions bring about a decrease in water absorption capacity and expansion ratio, as well as undesirable texture and microstructure. The results suggested that the properties of SPI-based TVP are directly influenced by the extrusion process parameters, screw speed and die temperature.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-022-01207-8.

Fortification of puffed biscuits with chitin and crayfish shell: Effect on physicochemical property and starch digestion

Chitin is a polysaccharide and possesses numerous beneficial properties such as nontoxicity, biodegradability and biocompatibility, which draws much attention to its applications in food. Crayfish shell is a source of chitin alongside an antioxidants and a potential source of beneficial dietary fiber. In this study, chitin (CH) and crayfish shell (CS) with different concentrations were used to study their impact on pasting characteristics of flour mixture (wheat flour and glutinous rice flour) and influence on physicochemical and starch digestion property of puffed biscuit. The Rapid Visco-Analyzer results showed that the viscosity of powder mixture was decreased with the ratio of CH and CS increased. CH resulted in lowest peak viscosity and breakdown values of mixed powder. It was indicated that increasing amounts of CH and CS led to significantly reduced moisture content, expansion ratio but raised density of biscuits. CH and CS inhibited starch digestion and promoted a remarkable increase (P < 0.05) of resistant starch (RS) content. The hydrolysis kinetic analysis suggested a decelerating influence of CH on the hydrolysis content with lower values of equilibrium hydrolysis percentage (C∞) while CS on hydrolysis rate with lower kinetic constant (K). The estimated glycemic index (eGI) of the CH (15-20%) samples were below 55. These results are of great significance in delaying starch digestion and provided a better choice in design of fried puffed snacks for special crowd with chronic diseases such as diabetes, cardiovascular disease, and obesity.

Effect of Marjoram Leaf Powder Addition on Nutritional, Rheological, Textural, Structural, and Sensorial Properties of Extruded Rice Noodles

Food-to-food fortification is an emerging technique to enrich the micronutrients in foods. Pertaining to this technique, noodles could also be fortified with natural fortificants. In this study, marjoram leaf powder (MLP) at a level of 2-10% was used as a natural fortificant to produce fortified rice noodles (FRNs) through an extrusion process. The MLP addition caused a significant increase in the iron, calcium, protein, and fiber in the FRNs. The noodles had a lower whiteness index than unfortified noodles but had a similar water absorption index. The water solubility index increased significantly due to the higher water retention ability of MLP. A rheological study showed a minimal effect of fortification on the gelling strength of the FRNs at lower levels. The microstructural studies found incremental cracks, which facilitated a lower cooking time and hardness but had an insignificant effect on the cooked noodle texture. Fortification improved the total phenolic content, antioxidant capacity, and total flavonoid content. However, no significant changes in bonds were observed, but a reduction in the noodles' crystallinity could be seen. The sensory analysis of the noodles reflected a higher acceptability of the 2-4% MLP fortified samples compared to the others. Overall, the MLP addition improved the nutritional content, antioxidant activity, and the cooking time but slightly affected the rheological, textural, and color properties of the noodles.

Yellow Pea Pasta Enhances the Saltiness and Suppression of Postprandial Blood Glucose Elevation

Salt and carbohydrates, two causes of elevated blood glucose, are essential components for survival; however, excessive intake of either is a known health risk. In a previous study, we reported the usefulness of pasta prepared from yellow pea (YPP) as a functional staple food that is beneficial for blood sugar control. In this study, we investigated the usefulness of YPP in reducing health risks by examining its effects on saltiness, postprandial satisfaction, and second meal. The results showed that YPP tasted saltier than conventional pasta made from semolina wheat when prepared with a 0.75% salt concentration. In addition, we examined blood glucose levels, insulin secretion, and postprandial hunger over a longer period than in previous studies. We observed that when the same amount of YPP and wheat pasta were eaten, the elevation in blood glucose and insulin secretion was lower after YPP consumption while maintaining a similar level of satiety. Furthermore, YPP was also observed to be able to suppress elevated insulin levels at the second meal.

Potential Health Benefits of Yeast-Leavened Bread Containing LAB Pediococcus pentosaceus Fermented Pitaya (Hylocereus undatus): Both In Vitro and In Vivo Aspects

This study aimed to investigate the effect of the incorporation of 0–25% pitaya (Hylocereus undatus) fermented by Pediococcus pentosaceus on physicochemical and bioactive properties of yeast-leavened wheat-mung bean bread. The results revealed that β-glucosidase activity increased during dough proofing, which may contribute to changes in dietary fiber. Compared to wheat bread, experimental bread had an increased content of soluble dietary fiber (SDF), total phenolic, total flavonoid, and slowly digestible starch, especially in wheat-mung bean bread prepared with 15% pitaya fermentates (WMB-15F). The effect of bread consumption on systemic inflammation, glucose tolerance, and blood lipid profiles was also evaluated via a mice model. The results indicated that levels of pro-inflammatory cytokines declined and glucose tolerance improved, while LDL and HDL were positively modified compared to control. Furthermore, an increased abundance of Lactobacillus, Lachnospiraceae, and Bifidobacterium spp. was observed in WMB-15F mice. Acetic acid was the dominant short-chain fatty acids (SCFAs) in feces and serum in all groups. Total SCFAs in circulation were highest in WMB-15F mice compared to other groups. In summary, an increased abundance of beneficial gut microbiota and promoted SCFA production might be highly associated with increased SDF and the release of key phenolic compounds during dough proofing, which exerts health benefits aroused from the consumption of yeast-leavened bread.

Extrusion Process as an Alternative to Improve Pulses Products Consumption. A Review

The development of new food products obtained by extrusion processing has increased in recent years. Extrusion is used by the food industry to produce a wide variety of food products, such as ready-to-eat foods (e.g., snacks), among others. Pulses have also gained popularity as novel food ingredients in the formulation of a variety of food and food products, due to their high content of macro and micronutrients, and bioactive compounds that improve the nutritional and functional properties of the final food products. In this review, the impact of extrusion variables on proteins, carbohydrates, vitamins, phenolics and antinutritional compounds in pulses and pulse-based formulations are highlighted. Particularly, the impact of the specific mechanical energy. Also, the preservation, increase and/or reduction in those functional compounds, as a consequence of different extrusion processing conditions, are discussed.

Considerations for functional food design based on starch-protein interactions: a systematic review

This systematic review aims to discuss the considerations in the design of starch-based foods from protein interactions, according to their functional, technological, and nutritional effects. Thereof, a systematic search for articles published in English, without excluding material by year, location, or author. Scopus and PubMed were the databases consulted. The results showed a decrease in gelatinisation, gelation, and viscosity of food matrices and a reduction in hydrolysis and starch digestibility rate by adding protein. Furthermore, found effects from other components such as phenolic compounds. In conclusion, in food design, protein interaction can modulate the starch digestibility rate, which also modifies technological, structural, and nutritional properties, depending on the physicochemical nature of ingredients, the percentage of protein incorporation, and processing conditions.

Whole seed lentil flours from different varieties (Brewer, Crimson, and Richlea) demonstrated significant variations in their expansion characteristics during extrusion

The properties of flours and extrusion characteristics, of three lentil varieties (Brewer, Crimson, and Richlea) were studied. The effects of barrel temperature (110, 125, and 140 °C) and screw speed (150, 200, and 250 rpm) on process responses and extrudate characteristics were evaluated using a corotating twin-screw extruder. The three varieties of lentils had significant differences (p < 0.05) in their starch (48.7% to 50.9%), protein (20.4% to 22.7%), and fat content (1.3% to 1.9%), gelatinization temperature (71.7 to 74.6 °C), peak viscosity (123.3 to 179.7 mPa.s), and melting temperature (113.6 to 119.7 °C). The lentil variety, barrel temperature, and screw speed significantly impacted the process responses and extrudate properties. Whole lentil flours exhibited the highest expansion ratio (3.0 to 3.6) at the lowest temperature (110 °C) and the highest screw speed (250 rpm). Richlea variety had the highest expansion ratio (3.6) and the highest water solubility index (45.4%) as it had the highest starch content and peak viscosity, and the lowest protein content and melting temperature. Meanwhile, Brewer variety exhibited the lowest expansion ratio (1.9 to 3.0) compared to Richlea (2.5 to 3.6) and Crimson (2.4 to 3.0) in most of the extrusion conditions studied. Richlea variety was the most suitable for making direct-expanded extrudates among the varieties studied. The significant differences in the properties of flours from the three varieties of lentils resulted in significant impacts on the properties of their extrudates. Therefore, determining the properties of flours of different varieties is useful to select the appropriate varieties for extrusion processing. PRACTICAL APPLICATION: The information from this study is useful for the food industry to select the appropriate lentil varieties and processing conditions for the development of direct-expanded products. The data prove the importance of understanding the chemical composition, pasting, and thermal properties to select the appropriate varieties for extrusion processing.

Effect of extrusion processing and addition of purple sweet potatoes on the structural properties and in vitro digestibility of extruded rice

Recently, extruded rice as a functional ingredient has been a hot area of research in food processing. In this study, extruded rice with purple sweet potato (ERPSP) was prepared. Moreover, the effects of extrusion and added purple sweet potato on the structure and in vitro digestibility of extruded rice were studied via numerous detection methods, such as scanning electron microscopy (SEM), water absorption index (WAI), water solubility index (WSI), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). SEM results showed that there were numerous pits and bubbles in the extruded rice. In particular, compared with raw rice, the WAI and WSI of ERPSP was higher, and the thermal properties also changed noticeably. The results of XRD and FT-IR spectroscopy showed that the semicrystalline structure of extruded rice changed from A-type to A + V-type mixture, and the relative crystallinity of extruded rice changed accordingly. In addition, a significantly lower equilibrium hydrolysis (C_∞) and kinetic constant (k) were observed in ERPSP. The novel rice product made from broken rice by extrusion processing and addition of the purple sweet potato exhibited improved structural properties and reduced digestibility, which increased the potential value and application of broken rice in the food industry.

Palatable Noodles as a Functional Staple Food Made Exclusively from Yellow Peas Suppressed Rapid Postprandial Glucose Increase

Legumes are low-carbohydrate food and are abundant in dietary fiber. In order to provide a functional staple food that does not cause a rapid increase in postprandial blood glucose levels, four kinds of legumes were focused on as ingredients. Noodles made from dehulled yellow pea, unshelled yellow pea, chickpea, and lentil were prepared and evaluated as functional staple foods for controlling blood glucose via an in vitro digestion method. We also measured breaking stress and breaking strain using a creep meter, as well as sensory tests on a 9-point hedonic scale. The noodles made from yellow pea had high values for both breaking stress and breaking strain, and was highly regarded in the sensory tests. Therefore, the noodles made from yellow pea on postprandial glucose and insulin response were measured in a randomized double-blind study (n = 12). The results show that noodles made from yellow pea have a low glycemic index (50.4), and have potential as a functional staple food.

Application of extrusion technology in plant food processing byproducts: An overview

The food processing industry generates an immense amount of waste, which leads to major concerns for its environmental impact. However, most of these wastes, such as plant-derived byproducts, are still nutritionally adequate for use in food manufacturing. Extrusion is one of the most versatile and commercially successful processing technologies, with its widespread applications in the production of pasta, snacks, crackers, and meat analogues. It allows a high degree of user control over the processing parameters that significantly alters the quality of final products. This review features the past research on manufacture of extruded foods with integration of various plant food processing byproducts. The impact of extrusion parameters and adding various byproducts on the nutritional, physicochemical, sensory, and microbiological properties of food products are comprehensively discussed. This paper also provides fundamental knowledge and practical techniques for food manufacturers and researchers on the extrusion processing of plant food byproducts, which may increase economical return to the industry and reduce the environmental impact.

Effect of physicochemical and rheological properties of flour from different local wheat varieties on the quality of varanphal: an Indian traditional product

Varanphal is an Indian traditional product which is similar to pasta. The suitability of four local varieties of wheat flour (Lokwan, Sharbati, MP cross S.H.R. and MP Lokwan) was determined by evaluating their physicochemical and rheological properties. The rheological properties such as farinographic characteristics, dough hardness, stickiness, and spreadability of dough were also evaluated for the same. Flour and dough properties of wheat varieties were correlated with varanphal quality characteristics. The correlation coefficient data indicated that amongst the physicochemical properties of flour such as protein, dry gluten, and damaged starch content were the indices in predicting the varanphal quality. The rheological properties such as farinograph water absorption, dough stability, hardness and spreadability were found to be highly correlated with varanphal quality. The strong relationship were observed between dry gluten content with spreadability, L* value flour with dough stickiness, dough hardness with protein content, dough hardness with overall acceptibility and cohesiveness of dough with the cohesiveness of varnaphal.

Processing Effect on L-DOPA, In Vitro Protein and Starch Digestibility, Proximate Composition, and Biological Activities of Promising Legume: Mucuna macrocarpa

Objective: In the present investigation, the effect of different cooking processes on L-DOPA level, phenolics contents, in vitro protein (IVPD) and starch digestibility (IVSD), and proximate composition with in vitro anti-inflammatory and antioxidant potential of Mucuna macrocarpa (MM) has been evaluated. Methods: The L-DOPA and major phenolics acids quantification of processed samples were done by a reverse-phase high-performance liquid chromatography (RP-HPLC) technique. Proximate composition, elemental quantification, and in vitro protein and starch digestibility of the samples were carried out by using spectrophotometric analysis. The anti-inflammatory activities of samples were evaluated by a human red blood cells (HRBCs) membrane stabilization test and bovine serum albumin (BSA) anti-denaturation assay. Antioxidant potential of processed beans was carried out by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and N,N-dimethyl-p-phenylendiamine (DMPD) assays and ferric reducing/antioxidant power (FRAP) assay. Results: The processed MM beans showed a significant reduction of L-DOPA (6.30%), phytic acid (25.78%), tannin (19.79%), and saponin (25.59%) in the boiling, autoclaving, and roasting processes. RP-HPLC quantification of major phenolics acids was also affected by the differential process as compare to the raw seed sample. The processed seeds also showed considerable improvement of in vitro protein (26.93%) and starch (20.30%) digestibility, whereas the anti-inflammatory potential and antioxidant potential of MM beans were decreased in the processed samples, indicating a reduction of antioxidant molecules. Conclusion: The differential process showed considerable changes in the proximate composition, in vitro digestibility, and biological potential. The present study recommends the utilization of MM beans after autoclaving and boiling for maximum nutritional potential with health benefits.

Extruded whole buckwheat noodles: effects of processing variables on the degree of starch gelatinization, changes of nutritional components, cooking characteristics and in vitro starch digestibility

The effects of processing variables on the degree of gelatinization (DG), changes of nutritional components, cooking characteristics and in vitro starch digestibility of extruded whole buckwheat noodles were investigated.

Enrichment of soybean dietary fiber and protein fortified rice grain by dry flour extrusion cooking: the physicochemical, pasting, taste, palatability, cooking and starch digestibility properties

With the prevalence of chronic conditions in patients due to a dietary imbalance, the demand for inexpensive, nutritious and high dietary fiber extruded rice is increasing rapidly. However, the factors of quality and bioavailability are still the major constraints to its development. In this study, soybean dietary fiber (DF) and protein fortified rice grain were prepared via dry flour extrusion processing. The results showed that the extruded rice had a similar density to that of natural rice and a significantly lower whiteness degree and transparency. Notably, the cooking texture and palatability of extruded rice were affected by the added amount of DF, resulting in rice with a taste value close to 70 in DF 6-9% (w/w) samples. The pasting properties, microstructure, and molecular interactions according to RVA, SEM and FTIR analyses, respectively, were also significantly affected by the DF content. The soluble dietary fiber was significantly increased from 0.0021 g g-1 to 0.216 g g-1 in extruded rice. Importantly, the starch digestibility in vitro showed significantly lower readily digestible starch (RDS) and higher resistant starch (RS) in DF 6-15% (w/w) extruded rice than in natural rice and DF-0 rice, respectively. The glycemic index (GI) was reduced in DF > 6%. In this study, we provide a new high dietary fiber extruded rice product with good texture and palatability, and we reveal the effect of DF on the extruded rice properties.