The impact of dehydration process on antinutrients and protein digestibility of some legume flours

Dehydrated foods are specially designed for patients with mastication or/and deglutition problems. This study has assessed the effects of soaking, cooking and industrial dehydration treatments on antinutrient factors and also on protein digestibility in legume flours (chickpea, lentil and bean). A general decline of phytic acid was observed during dehydration, being the most accentuated in case of lentil (44%), followed by white beans and pink-mottled cream beans. Beans were the legumes that showed the highest levels of enzyme inhibitors and lectins, however processing such as cooking and dehydration significantly reduced (p < 0.05) their levels further to negligible concentrations. The dehydration did not cause further effects than ordinary cooking in reduction of the concentration of polyphenolic compounds of flours. However, a higher increase of in vitro protein digestibility (IVPD) was produced by dehydration in all legumes from 12% to 15%. Thus, dehydrated legume flours could be considered ready-to-use for special meals to specific populations.     

Thermal heat processing effects on antinutrients,protein and starch digestibility of food legumes

Thermal heat processing effects were investigated on antinutrients, protein and, starch digestibility of black grams, chick peas, lentils, red and white kidney beans. The tannin and phytic acid contents in these five food legumes ranged from 770–1100 mg/100 g to 970–1440 mg/100 g, respectively, whereas protein and starch digestibilities of the raw food legumes were 33.0–37.6% and 36.8–42.0%, respectively. Reduction in the levels of antinutrients, along with an improvement in protein and starch digestibility, was observed after cooking these food legumes. Antinutrient, including tannin (33.1–45.7%) and phytic acid (28.0–51.6%) contents, were reduced by different thermal heat treatments (121AC10, 121AC20, 121AC40, 121AC60, 121AC90, 128AC20). Maximum improvement in protein (95.7–105%) and starch (117–138%) digestibilities was observed on cooking these food legumes at 121 °C for 10 min (121AC10). However, ordinary cooking resulted in improvement of protein and starch digestibilities of the food legumes by 86.0–93.3% and 84.0–90.4%, respectively.     

The impact of germination and dehulling on nutrients, antinutrients, in vitro iron and calcium bioavailability and in vitro starch and protein digestibility of some legume seeds

The content of nutrients (protein, starch, ash, calcium, iron, phosphorous and thiamin) and antinutritional components (dietary fiber fractions, phytic acid and tannin), and in vitro bioavailability of calcium and iron and in vitro digestibility of protein and starch were determined in control, germinated and dehulled green gram, cowpea, lentil and chickpea. Germination caused significant (P<0.05) increase in protein, thiamin, in vitro iron and calcium bioavailability and in vitro starch and protein digestibility contents of all the legume samples. Further increase in mentioned parameters was observed after dehulling the germinated legumes. Phytic acid and tannin were reduced by 18-21% and 20-38%, respectively, on germination and more reduction was observed in dehulled over germinated samples. There were negative correlations between nutrients bioavailability and digestibility with antinutritional factors.     

Effect of fermentation on the starch digestibility, resistant starch and some physicochemical properties of sorghum flour

The effect of natural fermentation of Tabat sorghum cultivar (Sorghum bicolor L. Moench) at 37 degrees C for up to 36 h on pH, titratable acidity, starch digestibility, resistant starch and total starch was studied. The pH of the fermenting dough decreased sharply with a concomitant increase in the titratable acidity. In vitro starch digestibility markedly increased as a result of fermentation, while resistant starch and total starch decreased. Results showed that iodine absorption capacity increased during fermentation. Fermented sorghum had more soluble starch and swelling power at 100 degrees C than at 85 degrees C.     

The effects of hydrothermal processing on antinutrients, protein and starch digestibility of food legumes

The effects of hydrothermal processing on antinutrients and the protein and starch digestibility of black grams, chick peas, lentils and red and white kidney beans was investigated. The tannins and phytic acid contents in these five food legumes ranged from 770 to 1100 and 970 to 1440 mg/100 g, respectively, whereas protein and starch digestibility of the raw food legumes was found to be from 33.8 to 37.6 and 36.8 to 42.0%, respectively. A reduction in the level of these antinutrients, along with an improvement in protein and starch digestibility, was observed after cooking. The tannins and phytic acid contents were reduced by 33.1–45.7 and 28.0–51.6%, respectively, because of the use of different hydrothermal treatments at 100, 121 and 128 °C. Maximum improvement in protein digestibility (95.7–105.1%) and starch digestibility (116.7–137.7%) was observed on cooking at 121 °C for 10 min. However, cooking in boiling water resulted in improvement in protein and starch digestibility of the food legumes by 86.9–93.3 and 84.0–90.4%, respectively.     

Effect of natural fermentation on phytate and polyphenolic content and in-vitro digestibility of starch and protein of pearl millet (Pennisetum typhoideum)

Natural fermentation at 20, 25 and 30°C for 72 h brought about a significant reduction in phytic acid content of pearl millet (Pennisetum typhoideum Rich) flour. The phytate content was almost eliminted in the flour fermented at 30°C. An increase in polyphenol content of fermented flour was noticed, the higher the temperature of fermentation the greater was the increase in polyphenol content of pearl millet. An improvement in starch as well as protein digestibility (in vitro) was noticed at all the temperatures of natural fermentation, the highest being at 30°C.     

Effect of various types of fermentation on in vitro protein and starch digestibility of differently processed pearl millet

Pearl millet (Pennisetum typhoideum) grains were fermented with Lactobacilli and yeast alone, in combination and with natural flora at 30 °C for 48 h after giving various processing treatments viz, fine and coarse grinding, soaking, debranning, dry heat treatment, germination and autoclaving after adding of water. Fermentation was carried out with Lactobacillus acidophilus and Rhodotorula isolated from naturally fermented pearl millet and Lactobacillus acidophilus, Candida utilis and natural fermentation using freshly ground pearl millet flour as inoculum. All the processing treatments except coarse grinding improved the protein and starch digestibility. Autoclaving enhanced the digestibilities of processed samples which was further improved by different types of fermentation, the maximum being in case of germinated and naturally fermented pearl millet. A combination of Lactobacilli and yeast was more effective in increasing the protein as well as starch digestibility as compared to pure culture fermentation.     

Effect of irradiation and other processing methods on in-vitro digestibility of rapeseed protein

Abstract. Effect of irradiation (1 kGy), autoclaving (121°C at 103.5 kPa for 5, 10, 15, 20, 25 and 30 min), dry heating (121°C for 5, 10, 15, 20, 25, 30 and 60 min), sprouting (36 h) and their combination on in-vitro digestibility of rapeseed protein was studied. Digestibility was significantly affected by processing methods (P < 0.05). Digestibility of untreated rapeseed protein was 85.7%. Irradiation alone and irradiation plus dry heating showed no effect on the digestibility, while irradiation plus autoclaving markedly improved (88.9%) the digestibility. The digestibility was influenced by the time of autoclaving and dry heating. Maximum value for in-vitro digestibility was recorded for 60 min of dry heating (91.8%). Sprouting of rapeseed exhibited a significant decrease (82.8%) in the digestibility.     

Effect of heat treatment on antinutrients and precaecal crude protein digestibility in broilers of four tropical crop seeds

Four tropical crop seeds, namely Vigna unguiculata (Cowpea), Mucuna pruriens, Manihot esculenta and Centrosema pubescens were thermally processed for 1 h at 100 °C and analysed for their antinutritional factors (ANF). Four hundred and forty‐eight 1‐day‐old broilers were used to determine the effect of heating the seeds on their precaecal crude protein (CP) digestibility. Total phenols, protein precipitable tannins and l ‐dopa were higher in the mucuna and centrosema seeds and diets than in the vigna and manihot seeds and diets. Phytic acid was of similar occurrence in all the raw seeds. Heat treatment resulted in reduction in all the ANF in the seeds. Precaecal CP digestibility, feed intake and growth rate were significantly (P < 0.01) increased in the heat‐treated mucuna and centrosema diets. There was no significant effect on the digestibility of CP, feed intake and growth rate in birds on the vigna and manihot diets owing to heat treatment of the seeds. The results showed that heating improved the nutritive quality of mucuna and centrosema seeds but was not of significant advantage with vigna and manihot seeds when used at levels of up to 150 g kg^?1 in diets.     

In-vivo and in-vitro digestibility of starch in autoclaved pea and potato products

The digestibility of starch in homogenized/autoclaved pea plus potato products was studied in vitro and in vivo. The products were a canned infant purée based on peas and potatoes and products prepared in the laboratory by repeated autoclaving and cooling of either homogenized potatoes or homogenized peas. Small-intestinal digestibility was evaluated through balance experiments in rats treated with an antibiotic (Nebacitin) to supress microbial activity in the hind gut. Parallel experiments in normal rats were performed to study the fermentability of undigested starch. The small-intestinal digestibility was 93, 82 and 70% of tolal starch in the potato product, infant purée and pea product, respectively. Consequently, significant amounts of starch left the small intestine undigested, particularly with pea-based products. The major portion of the undigested starch consisted of a fraction which resisted amylases in vitro unless solubilized in alkali, ie retrograded amylose. The fermentability of starch reaching the hind gut was high, about 90%. In-vitro digestibility figures varied depending on the method used and were in the ranges 91–93, 76–86 and 71–77% in the potato product, infant purée and pea product, respectively. One of the methods allowed simultaneous and accurate determination of the in-vivo resistant retrograded amylose fraction.     

Chemical composition and starch digestibility in flours from Polish processed legume seeds

The study was undertaken to determine the effect of various treatments, i.e. cooking after soaking, freezing after cooking and storage at a low temperature (-18°C, 21days), and autoclaving, of Polish cultivars of bean, pea and lentil seeds on the chemical composition and starch digestibility of the resultant flours. The cooking of seeds caused a significant decrease in contents of ash (by 11-48%), polyphenols (by 10-70%) and protein (to 19%) in flours made of bean. In addition, analyses demonstrated significantly decreased contents of resistant starch, RS (by 61-71%) and slowly digestible starch, SDS (by 56-84%). Storage of frozen seeds resulted in insignificant changes in the chemical composition, and in increased contents of both RS and SDS. The flours produced upon the autoclaving process were characterized by similar changes in the contents of ash and protein as in cooked seeds, yet losses of polyphenols were lower and, simultaneously, contents of RS and SDS were higher. All the analyzed flours were shown to be characterized by a reduced content of amylose in starch, which might have affected its digestibility. This was indicated by a strict negative correlation reported between the value of the starch digestion index (SDRI) and amylose content of starch (r=0.84, p>0.05).     

Effects of ribose, microbial transglutaminase and soy protein isolate on physical properties and in-vitro starch digestibility of yellow noodles

Soy protein isolate (SPI), microbial transglutaminase (MTGase) and ribose (R) were used to modify physical properties and in-vitro starch hydrolysis of yellow noodle. Four types of noodles were produced; noodles with SPI (SPI/C noodles), noodles with SPI and ribose (SPI/R noodles), noodles with SPI and microbial transglutaminase (SPI/MTGase noodles) and noodles with SPI, ribose and MTGase (SPI/R/MTGase noodles). γ-glutamyl-lysine bonds by MTGase and ribose-induced Maillard reaction within SPI were induced by incubating the noodles for 5 h at 40 °C followed by steaming for 30 min. Cooked noodles were assessed for physical properties such as pH, color, tensile strength and elasticity, and in-vitro hydrolysis index (HI) and estimated glycemic index (GI). SPI/R/MTGase and SPI/MTGase noodles exhibited significantly (P < 0.05) higher tensile strength and elasticity than SPI/R and SPI/C noodles. HI and GI were in the order; SPI/R/MTGase < SPI/MTGase < SPI/R < SPI/C noodles. Incorporation of SPI that was treated with MTGase and ribose may be useful for controlling the texture and starch hydrolysis of yellow noodles. These attributes may be due to the formation of γ-glutamyl-lysine bonds during incubation of SPI, and ribose-induced Maillard reaction during steaming of the noodles.     

Effect of fermentation and dehulling on starch,total polyphenols,phytic acid content and in vitro protein digestibility of pearl millet

Two pearl millet cultivars: Standard and Ugandi, obtained from El Obeid Research Station, were used in this study. Investigation showed that the Ugandi variety had significantly (P⩽0.05) higher polyphenols and phytic acid contents than the standard and significantly lower in vitro protein digestibility (IVPD), (72.7 and 70.4% for the Standard and Ugandi, respectively), indicating lower nutritional quality. The two cultivars were fermented for 14 h at room temperature (30±2° C) and starch, polyphenols, phytic acid and IVPD were determined at 2-h intervals. Dehulling was found to cause a significant reduction in protein, polyphenols and phytic acid contents for the two cultivars. Fermentation and dehulling caused a significant increase in the IVPD for the two cultivars: 82 and 84% for the fermented ones and 79.1 and 78.6% for the dehulled samples.     

Effect of processing on in vitro digestibility of protein and starch in quinoa seeds

The in vitro digestibility of protein in raw quinoa assessed by an enzymic method was 78%, significantly ( P > 0.01 ) lower than that of casein, 91%, and also somewhat lower ( P > 0.01) than that of the raw washed quinoa sample, 83%. the process used to remove the outer layers of the seeds containing saponins increased the protein digestibility significantly ( P > 0.01), by 7%. Heat treatments increased protein digestibility over that of raw quinoa samples. Only the cooked sample treated for 60 min presented a slightly lower protein digestibility, 77%, than those obtained for other heat-treated samples.
The temperature, time and moisture used in cooking and autoclaving of whole seeds of quinoa did not improve starch digestibility significantly. the digestibility of the starch in the raw and precooked samples was 72 and 77%, respectively, after drum drying and about 64% after extrusion in both cases. Precooking at 60°C for 20 min does not improve the digestibility of the quinoa starch.     

Effect of soaking process on nutritional quality and protein solubility of some legume seeds

Legume seeds (soy bean, lupin and bean seeds) were soaked in 0.5% sodium bicarbonate in attempt to evaluate their nutritional quality and protein solubility index. Soaking process led to an increase in the hydration coefficient, seed weight, total protein, ash, fat, fiber, while non protein nitrogen, total carbohydrates, starch, stachyose, raffinose, reducing sugars, and minerals (except Na) were decreased. All antinutritional factors such as phytic acid, tannin, trypsin inhibitor and hemagglutinin activity were decreased during soaking in 0.5% sodium bicarbonate; it was the same for the protein solubility in different solutions, while the in-vitro protein digestibility and available lysine were increased.     

Effect of soaking,dehulling, and cooking methods on certain antinutrients and in vitro protein digestibility of bitter and sweet lupin seeds

Effect of several physical treatments (soaking, dehulling, ordinary cooking, microwave cooking, and autoclaving) on the level of antinutrients and in vitro protein digestibility of bitter and sweet lupin seeds were investigated. The raw bitter and sweet lupin seeds were found to contain phytic acid, tannins, trypsin inhibitor activity, and lectin activity, but α-amylase inhibitor was absent. Dehulling significantly increased the levels of phytic acid (PA), trypsin inhibitor activity (TIA), and tannins, but lectin activity was not changed. Also soaking in bitter (for 96 hr) and sweet (for 24 hr) seeds caused a significant increase in these factors except lectin activity. Cooking methods differently affected the levels of the antinutrients. Thus, PA increased but tannins were not changed, on the other hand TI and lectin activities were inactivated; ordinary cooking and autoclaving were the most effective in both seeds. For combination effect, soaking following cooking treatments significantly decreased PA, tannins, and lectin activity, but increased TIA in both seeds. Moreover, dehulling following soaking and cooking methods resulted in a significant increase of PA, TIA, and tannins. In vitro protein digestibility (IVPD) of raw bitter and sweet lupin seeds were 78.55 and 79.46%, respectively and it was improved by all processing methods; soakingdehulling after autoclaving was the most effective in both seeds. Although some treatments increased the level of antinutrients, they improved IVPD. Therefore, the studied antinutrients are not the only responsible factor for lowering IVPD.     

Effect of natural fermentation on nutritive value and in vitro protein digestibility of pearl millet

Two pearl millet cultivars: Composite Population III, obtained from the Department of Agronomy, Faculty of Agriculture, University of Khartoum and Baladi, obtained from El Obeid Research Station, were used in this study. Investigation showed that Composite Population III is of higher tannin, total polyphenols and phytic acid and lower in in vitro protein digestibility (IVPD), which was found to be 60.5%. The two cultivars were naturally fermented for 36 h at room temperature (30±2 °C) and pH, moisture content, protein, tannin, total polyphenols, phytic acid content and IVPD were determined at 4-h intervals. Fermentation was found to cause a significant reduction in total polyphenols and phytic acid content for the two cultivars. Fermentation for 36 h at room temperature was found to cause no changes in tannin content of fermented dough for the two millet cultivars.     

湿热处理对玉米淀粉慢消化组分的影响

对玉米淀粉进行湿热处理,研究了处理条件对其慢消化组分含量的影响。通过正交实验确定了对玉米淀粉慢消化组分形成影响的顺序大小依次为:处理温度、处理时间、初始含水量,制备最佳条件为:温度120℃,初始含水量25%,处理3h,慢消化组分质量分数可达24.13%。湿热处理是提高玉米淀粉慢消化组分含量的有效途径。     

Effect of processing on starch digestibility in some legumes — An in vitro study

The effect of processing treatments on the rate of starch digestibility in three legumes, viz., bengal gram (Cicer arietinum L.), cowpea (Vigna unguiculata) and green gram (Vigna radiata) was studied using an in vitro dialysis system. The processes studied were fermentation, germination, pressure cooking and roasting. The released sugars measured as glucose equivalents after 3 h digestion were expressed as digestibility index (DI). All the processing treatments except roasting, increased the rate of starch digestibility in all the three legumes. Subsequent cooking of the germinated/fermented legumes lead to a further increase in starch digestibility. The results of the study indicate that ‘slow release’ property of legumes is heat labile and that loss of this property is independent of macro-nutrient and starch content.