Natural plant enzyme inhibitors. α-amylase inhibitors in millets

Twelve varieties of sorghum (Sorghum bicolor), 14 varieties of pearl millet (Pennisetum typhoideum), 12 varieties of setaria (Setaria italica), four varieties of ragi (Eleucine coracana), 11 varieties of echinocloa millet (Echinocloa colona), 13 varieties of proso (Panicium miliaceum), 11 varieties of kodo (Paspalum scorbiculatum) and 11 varieties of miliare (Panicium miliare) were screened for inhibitory activity against human salivary amylase. Echinocloa, proso, kodo and miliare had no detectable activity. Two strains of sorghum and one strain of pearl millet did not show α-amylase inhibitory activity. All other seeds had activity, the highest being observed in sorghum. Setaria had no action on human, bovine and porcine pancreatic anylases. Sorghum inhibitor did not act on bovine and porcine pancreatic amylases. Pearl millet and ragi extracts inhibited all the four α-amylases. The inhibitors were non-dialysable and were inactivated by pepsin treatment. Setaria and sorghum inhibitors were relatively thermolabile compared to ragi and pearl millet inhibitors.     

Effect of extrusion conditions on the physicochemical properties of a snack made from purple rice (Hom Nil) and soybean flour blend

Soy flour was added at levels of 5%, 10%, and 15% of Hom Nil rice flour for extrusion at 190 °C barrel temperature and 350 rpm screw speed. The extruded snack qualities decreased inversely with soy flour. However, product qualities were considered to be optimised when soy flour at 5% was added. The effect of feed moisture content (15, 17, 19 g (100 g)^?1 wb), barrel temperature (150, 170, 190 °C) and screw speed (350, 400, 450 rpm) on physicochemical properties of the snack were then investigated. The physicochemical properties of the product including expansion ratio, density, water absorption index (WAI), water solubility index (WSI) and hardness were evaluated. All properties were related, as linear equations, in terms of feed moisture content, barrel temperature, screw speed with relative correlation (R²) at 0.83–0.94. The snack properties along with consumer acceptance were all highest when the extruded condition were 15 g (100 g)^?1 wb feed moisture content, 170 °C of barrel temperature and 450 rpm of screw speed.     

Sustainable snack products: Impact of protein- and fiber-rich ingredients addition on nutritive,textural, physical,pasting and color properties of extrudates

The objective of this study was to explore the feasibility of incorporating mechanically deboned poultry meat (MDPM) and brewers spent grain (BSG) to corn based extruded snack products. The addition of protein- and fiber-rich ingredients creates nutritionally fortified snack product, however with lower quality of physical and textural characteristics and altered color. Therefore, the impacts of different MDPM (from 4 to 12%) and BSG (from 10 to 30%) concentrations and varying screw speeds (500, 700, 900 rpm) on physico-chemical properties of extruded snack products were investigated. Through optimization, with defined desired nutritional and physical characteristics and within the investigated range of input variables (MDPM, BSG and screw speed), the optimal product was defined. The optimized snack formulation contained 4% MDPM and 14.8% BSG, and it was produced at 900 rpm screw speed. Furthermore, the analysed parameters of the optimal snack demonstrated good agreement with the predicted values, indicating successful optimization.     

Cassava starch snack formulation using functional shell fish by‐products: mechanical,sorption and geometric properties

Utilisation of by‐products of the shrimp industry, namely shrimp head protein and chitosan, could lead to a functional snack with substantial market in Asia. Produced on a cassava starch base this would lead to a product with shrimp flavour and chitosan's lipid adsorption capacity. The characteristics of such a mixture with 82% deacetylated chitosan and salt was investigated by Rapid Visco Analyser and instrumental Texture Profile Analyser using the Doehlert Uniform Shell experimental design. Polynomial models explained more than 88% of variability of responses. A significant effect of salt, shrimp head proteins and chitosan was observed on cassava starch gelling characteristics. A corresponding heat and shear stress resistance ability was observed while there was a reduction in its specific swelling power. Snacks prepared in the form of chips and extruded product confirmed their good potential for added value to snack foods in respect of their 90–94% linear expansion ratio, up to 1.1 kg maximum breaking force and up to 4.5 radial expansion ratio. Adsorption isotherm of extrudates had a maximum water content target of 115 g kg^?1 dry matter at 25 °C for a later formulation and extrusion optimisation, in order to guarantee consumer texture acceptability. Corresponding shelf‐lives of extrudates were calculated at three storage conditions. Copyright © 2005 Society of Chemical Industry     

Rat bioassay of the protein nutritional quality of soy-fortified sorghum biscuits for supplementary feeding of school-age children

BACKGROUND: Protein–energy malnutrition (PEM) remains a major deficiency disease among children in developing countries. The protein nutritional quality of soy‐fortified sorghum biscuits was evaluated with respect to their potential as a protein‐rich supplementary food. Three isonitrogenous diets based on 50:50 ratio decorticated sorghum:defatted soy flour biscuits, 100% sorghum biscuits, casein, and a protein‐free diet were fed to male Sprague Dawley weanling rats. RESULTS: Protein efficiency ratio (PER) for the sorghum–soy biscuit diet was equivalent to the reference casein diet, and zero for the 100% sorghum diet. Faecal bulk for 100% sorghum diet was 1.5 times higher than sorghum–soy and casein diets. True protein digestibility of the three diets was high—88–95%—agreeing with previous rat studies with sorghum. Biological value and net protein utilization of the sorghum‐soy biscuit diet were similar to the casein diet, but lower than the 100% sorghum biscuit diet CONCLUSION: Notwithstanding limitations of rat bioassay for assessing sorghum food protein quality, the high PER of defatted soy flour‐fortified sorghum biscuits (sorghum:soy 50:50 ratio) indicates they have considerable potential as a supplementary food to young children to alleviate PEM. Copyright © 2011 Society of Chemical Industry     

Suitability of Oat, Millet and Sorghum in Breadmaking

Challenges and opportunities of minor cereals with poor viscoelastic value deserve a special attention in breadmaking applications due to their unique nutritional components. In a preliminary stage, the suitability of oat, millet and sorghum in breadmaking was assessed in simple binary wheat flour matrices in which wheat flour was replaced from 0% to 60%. The research allowed the quantification of grains (up to 30% for millet and sorghum and up to 50% for oat of wheat flour replacement) to be incorporated into the binary blended matrices providing minimization of techno-functional impairment and sensory depreciation of breads. Combinations of gluten, vegetable fat and a commercial mix of surfactants, ascorbic acid and antistaling enzymes were used to make breads with 10% increased level of wheat flour replacement by single oat, millet and sorghum in binary mixed samples. The quality profile of binary mixtures of oat–wheat (60:40 w/w), millet–wheat (40:60 w/w) and sorghum–wheat (40:60 w/w) was significantly improved in terms of keepability during storage, mainly for oat–wheat blends which stale at a similar rate than 100% wheat breads. Overall acceptability of highly replaced wheat breads deserved higher scores for oat and sorghum composite breads (7/10) than control wheat breads (6/10). Oat, millet and sorghum represent a viable alternative to make aerated breads with mitigated technological and sensory constraints based on non-viscoelastic cereals.     

Extrusion cooking of barley flour and process parameter optimization by using response surface methodology

BACKGROUND: The nutritional profile of barley places it in a prime position for development of a new extruded–expanded snack food with health benefits. It was therefore the aim to investigate the effect of extrusion processing variables on system parameters (specific mechanical energy, die pressure and die melt temperature) and physical properties (expansion, bulk density, texture and color) of barley flour extrudates and to optimize processing conditions for production of extruded snack food from barley flour by response surface methodology. RESULTS: Barley flour with 219.7 g kg^?1 moisture content was extruded at different die temperatures (140–160 °C) and screw speeds (150–200 rpm) through a co‐rotating twin‐screw extruder. The system parameters as well as product responses were mainly dependent on temperature, whereas the screw speed imparted a lesser effect. Extrudates produced under extrusion conditions of 160 °C, 150 and 200 rpm and at 164 °C and 150 rpm had higher preference levels of appearance, taste, texture and overall acceptability than that of other selected extrudates for sensory analysis. The optimal conditions for minimum bulk density and desired textural characteristics and color of extrudates correspond to a temperature of 156 °C and screw speed of 166 rpm. CONCLUSION: The results suggested that use of barley flour in extruded snack products offers a desirable variation in diet and can take advantage of the nutritional quality of barley. Copyright © 2008 Society of Chemical Industry     

Process development of a chocolate-flavoured peanut–soy beverage

A new beverage product was developed utilising two protein‐rich oilseed sources, namely peanut and soy. Medium‐roasted peanut flour and chocolate flavour were incorporated to offer pleasant flavour profile. The peanut–soy combination would also improve essential amino acid profile, especially that of lysine, compared with an all‐peanut product. A pilot‐plant scale beverage‐processing protocol involved filtration, homogenisation and pasteurisation as the major operating steps. Beverage formulation employed a three‐component constrained mixture design. The low‐ and high‐bound constraints were determined for peanut (30.6–58.7%), soy (28.3–43.5%) and chocolate syrup (13.0–25.9%) based on lysine content, viscosity and visual stability index values of 51‐mg g^?1 protein, 36.9 mPa s and 1.00, respectively. The beverage formulation and processing protocol thus developed were the basis for further study on consumer acceptability of the new chocolate‐flavoured peanut–soy beverage.     

Development of protein-Rich Sorghum-Based Expanded Snacks Using Extrusion Technology

Sorghum is an important staple crop in semi-arid regions of Africa and India because of its drought tolerance. But low protein content and quality limit its widespread use. This project focused on developing sorghum-based extruded snacks. Results from preliminary lab-scale extrusion experiments were used to design a 2×5 factorial pilot-scale study. Two blends of sorghum flour and corn flour were prepared (6:1 and 5:2 w/w ratios) as the controls. Three different sources of protein—whey protein isolate, defatted soy flour, and mixed legume flour—were added to the sorghum/corn flour blends at 30%. A 50:50 blend of defatted soy flour and whey protein isolate was also added at 30% to the sorghum/corn flour blends. The resultant ten formulations were extruded on a pilot-scale twin-screw extruder to investigate the effects of sorghum/corn flour ratio and protein addition on product expansion, microstructure, mechanical properties, and sensory attributes. Expansion ratio of extruded product increased at the higher level of corn flour, and decreased with the incorporation of protein sources. Extrudates with defatted soy flour had a lower expansion ratio (5.3–5.4) than those with whey protein isolate (7.7–7.9), legume flour (7.1–9.9), or whey protein isolate-defatted soy flour (6.1–6.9). Extrudate microstructure, obtained by X-ray microtomography, corresponded well with expansion characteristics. Extrudates with defatted soy flour had the lowest cell diameter. Average crushing force (ranging from 40.9 to 154.87 N) was lower for extrudates with a higher level of corn flour. However, contrary to expectations, crushing force and crispness work both decreased with incorporation of protein sources. Consumer acceptability results showed that the addition of protein sources enhanced taste and overall acceptability of the extruded snacks, with the treatment sorghum/corn flour 5:2 and whey protein isolate-defatted soy flour as the protein source having significantly higher ratings than the other treatments.     

Acceptability of Extruded Corn Snacks as Affected by Inclusion of Soy Protein

Our objectives were to develop acceptable extruded snack products containing soy protein, and to evaluate the influence of soy protein type, soy level, and moisture content. Addition of soy protein increased die temperature and pressure while decreasing motor torque. Results of two consumer tests for 12 prototype products and the most acceptable three samples indicated positive responses. Acceptance correlated highly with consumer attitudes toward soy foods and prior information about health effects of soy protein. Differences between protein types suggested that formulation optimization could develop highly acceptable soy/corn extruded snacks.     

Unavailable carbohydrates of commonly consumed indian foods

The importance of unavailable carbohydrates in normal and therapeutic diets has been recognised in recent years. The profile of these substances is believed to be as equally important. The literature crude fibre estimation gives gross underestimates of the total unavailable carbohydrates in foods. The unavailable carbohydrate content and profile of some common Indian foods was studied by the recent method of Southgate (1976). Amongst cereals, the unavailable carbohydrate was the lowest in rice (8.3%) and highest in pearl millet (20.3%), with sorghum, wheat and ragi having intermediate values. The crude fibre values reported for rice was only 0.2% and that for pearl millet, 1.2%. In the case of legumes, green gram had the lowest (15.2%) and Bengal gram the highest (25.6%), with black gram and red gram having intermediate values. When unavailable carbohydrates were expressed as a proportion of the total carbohydrates, pulses had considerably larger amounts than did all cereals except pearl millet. Estimated ranges of values (g 100 g^?1 of the edible portion of the food) for unavailable carbohydrates were; in roots and tubers (3.5–7.9%), peanut varieties (5.4–6.8%), green leafy vegetables (2.9–4.0%), other vegetables (0.4–6.0%) and fruits (2.2–2.7%).     

Natural plant enzyme inhibitors. Protease inhibitors in millets

Protease inhibitory activities were screened in 12 varieties of pearl millet (Pennisetum typhoideum), 12 varieties of echinocloa (Echinocloa colona), 12 varieties of setaria (Setaria italica), 11 varieties of kodo (Paspalum scorbiculatum), 13 varieties of proso (Panicium miliaceum), 11 varieties of miliare (Panicium miliare), 29 varieties of sorghum (Sorghum bicolor) and four varieties of ragi (Eleusine coracana). Proso, miliare and kodo had no detectable inhibitory activity. Pearl millet, setaria and echinocloa millets displayed only antitryptic activity. Ragi had both antitryptic and antichymotryptic activity. Two varieties of sorghum had neither antitryptic nor antichymotryptic activity. In most other strains of sorghum, the antichymotryptic activity was more than the antitryptic activity. Pearl millet, setaria, sorghum and echinocloa extracts inhibited the proteolytic activity of both human and bovine pancreatic preparations.     

Physical evaluation of a maize‐based extruded snack with curry powder

Response surface methodology was used to analyze the effect of screw speed (200–280 rpm), feed moisture (13.0–17.0%, wet basis), and curry powder (6.0–9.0%) on the bulk density, lateral expansion, and firmness of maize‐based extruded snack with curry powder. Regression equations describing the effect of each variable on the responses were obtained. Responses were most affected by changes in feed moisture followed by screw speed and curry powder (p < 0.05). Lateral expansion increased linearly as the amount of curry powder added was increased whereas a quadratic increase was obtained in lateral expansion with decreasing feed moisture. The firmness of samples was increased with an increase in feed moisture. The bulk density of samples was increased with increasing feed moisture and screw speeds. Radial expansion was found to be a better index to measure the physical properties of the extruded product indicated by a higher correlation coefficient.     

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Grain samples of nine varieties of pearl millet (P. typhoides) and six varieties of ragi (E. coracona) were analysed before and after malting for total ash, phosphorus, phytin phosphorus, calcium, magnesium, iron, zinc, manganese, copper and chromium contents. Pearl millet alone varietal differences were significant for iron, manganese and chromium contents. Significant nutrient losses in malting were, in pearl millet: iron and manganese, 40%; copper, 30%, and phosphorus, 25% and, in ragi: calcium, 40%; zinc, 30% and copper 25%. As judged by an in vitro method, the availability of iron and zinc in millets improved several fold on malting. The values for ionizable iron (mg per 100 g of raw and malted grains) were 0·64 and 2·70 in pearl millet and 0·29 and 2·98 in ragi. Soluble zinc contents per 100 g of raw and malted grains, respectively were 2·04 and 5·25 mg in pearl millet and 2·15 and 3·24 mg in ragi. Reduction in phytin phosphorus on malting of these millets partly explained the improved availability of iron and zinc.     

Optimisation of wheat flour‐based sponge cake formulation containing tapioca starch and xanthan gum

The optimum formulation for wheat flour (WF)‐based sponge cakes containing tapioca starch (TS) and xanthan gum (Xan) was determined using the central composite design with two factors and response surface methodology (RSM). Effects of partial substitution of TS (5–15%) for WF in a 20% total flour blend and Xan (0.1–0.3%) on specific volume, parameters of texture profile analysis and sensory liking scores of baked sponge cakes were investigated. A second‐order polynomial response surface was used to explain the influence of TS and Xan on the dependent variables. Coefficients of determination (R² ≥ 0.75) of the response variables and significant regression models were used for RSM optimisation. Based on the RSM contour plots, the cake formulation containing 16% butter with desired physical properties (maximum specific volume; minimum hardness, gumminess and chewiness) and sensory quality (maximum overall liking) was found to be 11.09–11.88% TS and 0.10–0.11% Xan.     

A comparison of satiety, glycemic index, and insulinemic index of wheat-derived soft pretzels with or without soy

The consumption of nutrient-poor snack foods in Western diets is thought to be contributing to the increasing prevalence of obesity and diabetes. Soy offers unique potential to provide high quality protein, dietary fiber, and phytochemicals to snack foods to produce a more healthful nutritional profile. In this study, 27.3% of wheat flour was replaced with soy ingredients in a soft pretzel and evaluated for impact on satiety, glycemic index (GI), and insulinemic index (II). We first tested the soy pretzel for consumer acceptability by 51 untrained sensory panelists on a 9-point hedonic scale. Second, in a crossover trial, 20 healthy adults consumed soy and traditional pretzels (1000 kJ or 239 kcal each) after an overnight fast. They reported their levels of satiety on a 10 cm visual analog scale (VAS) for 2 h postprandially. Third, 12 healthy, non-diabetic subjects consumed soy or traditional pretzels (50 ± 2 g available carbohydrates) to determine the GI and II of both products. Blood glucose and insulin responses were monitored for 2 h after consumption and compared to a glucose reference. It was found that a consumer-acceptable soy soft pretzel had a lower mean (±SD) GI than its traditional counterpart: 39.1 (±20.4) for soy and 66.4 (±15.3) for wheat, (p = 0.002). However, soy addition did not statistically affect II (p = 0.15), or satiety (p = 0.91). In conclusion, a nutrient-dense soy pretzel formulation with 27.3% of wheat flour replaced by soy ingredients had attenuated postprandial glycemia without significantly affecting insulinemia or satiety in healthy adults.     

Physicochemical properties of ready‐to‐eat extruded nixtamalized maize‐based snacks enriched with grasshopper

The aim of this research was to prepare an extruded snack based on nixtamalized maize flour (Zea mays L.) (NMF) enriched with grasshopper meal (Sphenarium purpurascens Ch.) (GM) using a single screw extruder with a compression screw ratio of 3:1. A central experimental design comprising three independent variables, namely, extrusion temperature (T = 120–180 °C), feed moisture content (FMC = 18–22 g/100 g) and the grasshopper meal proportion (GMP = 0–40 g/100 g), was used. Increasing T decreased (P < 0.05) the expansion index (EI), bulk density (BD) and hardness (H). Increasing the FMC increased (P < 0.05) the EI. Increasing the GMP decreased (P < 0.05) the EI, H and water absorption index (WAI) and increased (P < 0.05) the BD and total colour difference (ΔE). The treatments that resulted in better general acceptability were those that contained a lower GMP. An extruded snack acceptable to the consumer can be obtained from a blend of NMF and GM, and up to 8.11 g/100 g of GM can be incorporated without affecting the physicochemical properties and acceptance of the snack.     

Antioxidant potential and quality characteristics of Mediterranean fruit‐based extruded snacks

‘Mediterranean snacks’ (dried fruits and nuts as principal ingredients), a little known food product with a high nutritional value, might be considered a good alternative for consumers looking for healthy snacks. The aim of this research was to determine the physicochemical properties and nutritional value of this type of food stuff (traditionally called ‘fruit cakes’ in Mediterranean countries) and to evaluate their phenolic content and antioxidant activity. All the fruit‐based extruded snacks studied are shelf‐stable at room temperature (because of their pH and water activity values). The final product has a low moisture (<32%) and high sugar content (>30%), the only sugars being those naturally present in the food. All the fruit‐based extruded snacks had a dietary fibre content higher than 10% (high‐fibre foods). Date extruded snack and apricot extruded snack showed the highest total phenolic and flavonoid content and also the highest antioxidant activity as determined by the DPPH and FRAP methods.     

Optimisation and comparative study on the addition of shrimp protein hydrolysate and shrimp powder on physicochemical properties of extruded snack

The effect of an addition of shrimp protein hydrolysate and shrimp powder on the physicochemical properties of extruded snack was studied. Rice flour and cornflour were used as base materials, and extrusion was done using corotating twin‐screw extruder. A mixture response surface methodology was used to study the effect of ingredient mixture on the physical, functional and sensory properties of extrudates. Linear and quadratic mixture response regression model was fitted to the response variables, and it was evaluated using R² values. Based on the desirability function score, the optimum combination of ingredient was 47.75% rice flour, 38.64% cornflour, 5.95% hydrolysate and 7.67% shrimp protein powder. It was observed that an addition of shrimp hydrolysate more than 5% (7.5%) improved the crispiness. Sensory evaluation revealed that shrimp hydrolysate and shrimp powder can be used at 5–7.5% level for developing protein‐rich extruded products without affecting sensory characteristics.