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.     

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.     

FACTORS AFFECTING THE COOKING QUALITY OF FIELD PEAS (PISUM SATIVUM L.) AND WHITE BEANS (PHASEOLUS VULGARIS L.) STORED UNDER SIMULATED FARM CONDITIONS

Factors affecting the cooking, physical, chemical, and biological characteristics of field peas and white beans were studied after 147 days’ storage under northern temperate climatic conditions. Cooking time, hydration and swelling characteristics, phytate levels, fat acidity values (FAV), off-odor and visible mold development were assessed. Among the different initial moisture contents and storage temperature regimens investigated, only the highest temperature regimen (44C declining to 15C) was associated with a noticeable reduction in the cooking quality of peas and beans. Although a gradual decline was seen in the hydration and swelling characteristics of both legumes, and in phytate levels of peas stored at the 44C to 15C regimen, no single factor appeared to explain the changes in cooking quality of peas and beans stored at high temperatures. Correlation analyses indicated the association of high levels of conductivity and FAV with poor hydration characteristics and off-odor development in the two legumes.     

Zinc and Phytate Distribution in Peas. Influence of Heat Treatment, Germination, pH, Substrate, and Phosphorus on Pea Phytate and Phytase

The largest proportions of zinc and phytate, 88.7 and 97.1%, respectively, were in the Garfield pea cotyledon; the greatest concentrations were in the germ. Cooking peas by two different methods resulted in 13% phytate reduction. Peas incubated 6.5 hr from 25 to 80°C yielded maximum phytate loss (25%) at 60°C due to phytase activated hydrolysis. Germination (10 d) decreased pea phytate 75% and increased phytase activity 12-fold. Semi-purified germinated pea phytase showed temperature optimum at 45°C, pH optimum of 5.2, 30% inhibition by 1 mM inorganic P, and substrate preference for pyrophosphate. Incubation of early germinated peas at optima pH and temperature is suggested for maximum phytate reduction.     

The influence of tempeh fermentation and conventional cooking on anti‐nutrient level and protein bioavailability (in vitro test) of grass‐pea seeds

BACKGROUND: The solid state fermentation tempeh type is known to result in the decomposition of anti‐nutrients and the improvement of nutritional value of legume seeds. The aim of the research was to study the influence of tempeh fermentation and conventional cooking on (1) levels of 3‐N‐oxalyl‐L ‐2,3‐diaminopropionic acid (ODAP), soluble phenols, trypsin inhibitors and inositol phosphates; and (2) the in vitro bioavailability of proteins in grass‐pea seeds. RESULTS: Tempeh fermentation reduced the level of ODAP, trypsin inhibitors and phytates by 93, 99 and 22%, respectively, and increased protein bioavailability by about 25%. Protein bioavailability from conventionally cooked seeds was higher than from fermented seeds. However, during the in vitro test more soluble protein (approx. 10%) was released from 100 g tempeh product than from cooked seeds. CONCLUSIONS: Solid state fermentation and cooking resulted in seeds of comparable quality but the tempeh contained much less ODAP, which is very promising in the context of popularising grass pea. Copyright © 2008 Society of Chemical Industry     

Effect of cooking and germination on antioxidant activity,total polyphenols and flavonoids,fiber content,and digestibility of lentils (Lens culinaris L.)

The aim of this work was to evaluate the effect of cooking and germination on antioxidant activity, total polyphenols and flavonoids, fiber content, and digestibility of lentils (Lens culinaris L.). Seven commercialized samples of lentils (brown, red, dark green, French green, Beluga, dehulled and split red, and dehulled yellow) obtained from the Czech market were analyzed. Lentils were assessed for basic chemical analyses (dry matter and ash content), total phenolic and flavonoid contents (Folin‐Ciocalteu and AlCl₃·6H₂O spectrophotometric methods, respectively), antioxidant analysis (DPPH assay), crude and neutral‐detergent fiber contents and in vitro digestibility. Germination caused an increase in total phenolic and flavonoid contents, antioxidant activity, and digestibility and, contrariwise, a decrease in both crude and neutral‐detergent fiber contents. Cooking resulted in the rising of digestibility and the reduction of total phenolic and flavonoid contents, antioxidant activity, and both crude and neutral‐detergent fiber contents.

Practical applications

Lentils, among other legumes, exert valuable nutritional composition (including high amounts of protein, fiber, and bioactive compounds with antioxidant activity, such as polyphenols). However, lower digestibility together with some antinutritional factors results in very low consumption of lentils in western diet. Lentils need to be processed prior to consumption. The most widely used processing methods represent thermal processing (cooking) and germination. These processing techniques can influence nutritional quality of lentils since antinutritional factors are reduced. It is crucial to monitor the changes occurring during the culinary processes and to ensure that these processes implicate positive affection of nutritive value of lentils. According to our results, both processing techniques resulted in enhanced digestibility of lentils. Furthermore, germination proved to be more efficient in the antioxidant activity improvement caused mainly by the increased amounts of polyphenols and flavonoids.     

Antioxidant activity and phenolic content of lentils (Lens culinaris), chickpeas (Cicer arietinum L.), peas (Pisum sativum L.) and soybeans (Glycine max), and their quantitative changes during processing

Total phenolic content (PC) was ～12 mg g^?1 in lentils, 2.2 mg g^?1 in chickpeas, 2.3 mg g^?1 in soybeans, 2.5 mg g^?1 in yellow peas and 1.2 mg g^?1 in green peas. Total antioxidant activity (AA) determined by ABTS (2,2′‐azinobis‐3‐ethyl‐benzthiazoline‐6‐sulfonic acid) assay was highest in lentils at around 14 μmol Trolox equivalent antioxidant capacity (TEAC) g^?1 and lowest in green peas at 1.9 μmol TEAC g^?1. Bound phytochemicals contributed to 82–85% total AA in lentils. Free phytochemicals contributed more to total AA in chickpeas, yellow peas, green peas and soybeans than bound phytochemicals. AA and PC was reduced by ～80% in lentils and <30% in yellow peas by decortication, by 16–41% in lentils, chickpeas and peas by cooking, and by 22–42% in lentils by soaking. Total AA was significantly correlated with total PC. Soybeans had the greatest ability to scavenge free radicals, inhibit lipid peroxidation and chelate metals among the legumes tested. Different legumes exhibited different AA mechanisms.     

Legume Processing Effects on Dietary Fiber Components

Effects of different processes were studied on neutral detergent fiber (NDF), acid detergent fiber (ADF), cellulose, and lignin content of legumes. Chick peas, kidney beans, and lentils were soaked and cooked, simulating home processing. Values were recorded on a wet basis as a guide to calculating their contribution to the diet. Decrease in values was more pronounced in pressure-cooked chick peas and kidney beans with cooking liquid removed. In lentils, cooking liquid embedded, no difference between processes was observed. Amounts of dietary fiber components on a dry basis, of interest when legume meal is used as food supplement, increased for chick peas and beans, except for the hemicellulose of beans and lentils, which decreased.     

EVALUATION OF EFFECTS OF SOAKING AND PRECOOKING CONDITIONS ON THE QUALITY OF PRECOOKED DEHYDRATED PEA, LENTIL AND CHICKPEA PRODUCTS

Peas, lentils and chickpeas were blanched and soaked in water, then cooked with four different cooking methods and dehydrated in a convection tray dehydrator. Color, splitting and butterflying rate; firmness; and rehydration rate were evaluated. Dehydrated yellow and green peas produced by soaking at 22C for 9 h and 82C for 4 h in 0.07% NaHCO₃ solution, and followed by precooking at 110C for 10 min had the best quality with respect to firmness, splitting and butterflying rate. Dehydrated chickpeas produced by soaking at 22C for 9 h and 82C for 3 h in 0.07% NaHCO₃ solution, and followed by precooking at 110C for 10 min had the best quality. Dehydrated lentils produced by soaking at 22C for 2 h and 82C for 20 min in 0.07% NaHCO₃ solution, and followed by precooking at 106C for 10 min had the best quality.

PRACTICAL APPLICATIONS

Traditionally, soaking and cooking of peas, lentils and chickpeas (PLCs) takes one a long time. It is desirable to manufacture dehydrated precooked PLCs to provide convenience for the users. The objective of this study was to investigate the quality of precooked dehydrated PLCs as affected by processing. The fundamental cooking characteristics of PLCs obtained in this study are very useful for the food industry.     

Germinated Cajanus cajan seeds as ingredients in pasta products: Chemical,biological and sensory evaluation

Pigeon peas (Cajanus cajan) seeds were germinated for 4 days at 20 °C in darkness in order to improve the nutritional quality of seeds. Germination brought about a sharp reduction of α-galactosides, phytic acid and trypsin inhibitor activity (83%, 61% and 36%, respectively) and an increment of vitamin B₂ (145%), vitamin C (from negligible amounts to 14 mg/100 g d.m.), vitamin E (108%) and total antioxidant capacity (28%). These flours were used as ingredients to produce pasta products in a proportion of 5%, 8% and 10%. The supplemented pasta products had shorter cooking time and higher water absorption, cooking and protein losses in water than had control pasta (100% semolina). From sensory evaluation, fortified pasta generally had acceptability similar to control pasta. Cooked pasta with the highest level of substitution (semolina:germinated pigeon pea flour at 10%) was chemically and biologically evaluated and results showed that protein, fat, dietary fibre and mineral contents were improved. Fortified pasta provided more vitamin B₁, B₂, E and antioxidant capacity than did control pasta. Biological assessment of fortified, cooked pasta indicated that true TD and PER value increased by 12% and 64%, respectively, in comparison with control. The germinated pigeon pea flour can be an excellent ingredient to increase the nutritional value of semolina pasta without affecting the sensory properties.     

Effect of processing on phosphorus and phytic acid contents of some Egyptian varieties of legumes

Phytic acid and total phosphorus contents were determined in different varieties of dry legume seeds—broad beans, lentils, lupin, fenugreek, chickpea and peas. These seeds are widely used in Egypt. The dry seeds were subjected to different processing methods according to the mean of their consumption in Egypt. These processing methods include decortication, steeping, sprouting, boiling and cooking. Phytic acid and total phosphorus contents of seeds differed according to the kind, the variety and the processing method. Steeping and sprouting decreased the phytic acid content of the seeds. The phytic acid content of lupin was greatly reduced by decortication and by steeping of seeds.     

Inositol phosphate degradation by the action of phytase enzyme in legume seeds

The kinetics of inositol phosphate degradation during the action of naturally occurring endogenous phytase for up to 90 min in pea and lentil flours has been studied, and compared with the addition of commercial phytase enzyme. In raw lentils IP₆, IP₅, IP₄ and IP₃ were present, whilst in peas only the presence of IP₆ and IP₅ was observed. Endogenous phytases were activated when legume flour was suspended in acidified water at pH 5.5 and 37 °C, and significant differences between lentils and peas were found. IP₆ suffered a sharp reduction in lentils and peas (81–91 and 73–93%, respectively), this reduction being slightly more pronounced after the addition of commercial phytase. The content of IP₅ decreased in lentils (48–69%), and increased in peas, except when commercial phytase acted for the first 30 min, after which a reduction was found (23%). The content of IP₄ generally decreased in lentils, except when endogenous phytase acted for 30 min when an increase was observed. However, in peas, IP₄ appeared in high concentrations up to 60 min by the action of both endogenous and exogenous phytases. The content of IP₃, on the other hand, did not change greatly in lentils. In peas it was not detected after the action of endogenous phytase enzyme and it appeared in a large amount after the action of commercial phytase. In order to obtain legume flour with low IP₆ and IP₅ contents and notable IP₄ and IP₃ contents, the action of naturally endogenous phytase for 30 min in lentils is recommendable, as well as the addition of commercial phytase enzyme for 60 min in peas.     

Nutritional value of African yambean (Sphenostylis stenocarpa,L): improvement by solid substrate fermentation using the tempeh fungus Rhizopus oligosporus

The tropical African yambean (AYB, Sphenostylis stenocarpa L.) is a hardy, protein‐rich under‐utilised African legume. Anti‐nutrients, and the excessively long cooking time (4–6 h), among other factors, limit the food use of African yambean seeds. To reduce these limitations, non‐traditional, less energy consuming processing methods are required. Seeds of different varieties were (1) examined for proximate composition and (2) fermented with Rhizopus oligosporus for the production of tempeh. The traditional production process involves dehulling, soaking in water for 24 h, boiling in water for 30 min, inoculation and fermentation. In addition, the traditional procedure for preparing tempeh was modified by using 1% citric acid solution instead of water for soaking and cooking. Comparisons with traditionally cooked beans, which involved boiling in water for 4 h, were made. The traditional tempeh procedure resulted in a slight but significant increase in protein and starch (P < 0.05) and an almost complete loss of most of the anti‐nutrients of AYB seeds, although the cyanogenic glycoside content of AYB‐white remained high. The modified procedure resulted in a bacteria‐free tempeh and the cyanogenic glycosides were no longer detectable. In vitro protein digestibility of the 1% citric acid treated sample was slightly lower than that of the water‐treated sample. Both tempeh production processes were clearly more effective and less energy intensive than traditional cooking in improving nutritional quality, but only the modified method of tempeh production eliminated the possibility of cyanide poisoning. Copyright © 2006 Society of Chemical Industry     

PHYSICAL AND COOKING PROPERTIES OF MICRONIZED LENTILS

The potential for reducing the cooking time of lentils by micronization was studied. The effect of infrared heat and initial seed moisture on the internal temperature of lentil seeds was monitored up to the stage of seed browning. The seed physical properties, water uptake by seeds, cooking time and starch properties were determined. The cooking time was shortened from 30 min for the control seeds to 15 min for lentils adjusted to 25.8% wb moisture content and micronized for 55s to 18.0% wb moisture. Micronization was effective in gelatinizing and solubilizing 45 to 65% of the starch in the lentil seed, depending on the initial seed moisture content.     

Firmness, seed wholeness and water uptake during the cooking of lentils (Lens culinaris cv. anicia) for 'sous vide' and catering preparations

The study aimed to optimize cooking conditions of lentils ( Lens culinaris cv. anicia ) for 'sous vide' processing and catering. the softening rate of lentil seeds during cooking in deionized water was consistent with two simultaneous first order mechanisms. the apparent activation energies of firmness breakdown and loss of integrity were 86.5 kJ mol⁻¹ and 271.3 kJ mol⁻¹, respectively. Wholeness of the lentils was better preserved when the cooking temperature did not exceed 90°C. the loss of firmness was a consequence of hydration of the seed since the regression coefficient between the logarithm of residual firmness and water uptake reached −0.93 regardless of cooking temperature and heating medium (steam or water). Thus, lentil seeds maintained their firmness and wholeness as required for 'sous vide' and catering if they were cooked below 90°C for up to 2 h. Higher temperature or longer cooking time resulted in loss of firmness and wholeness.     

Distribution of Phosphorus and Phytate in Some Nigerian Varieties of Legumes and Some Effects of Processing

Phytate anion, total phosphorus (P), phytate-P, inorganic and residual P contents were determined in different varieties of cowpeas, lima beans and soybeans. The dry seeds were subjected to different processing methods which included cooking, autoclaving, soaking and germination. Germination and soaking were most effective in decreasing phytate contents while cooking and autoclaving only slightly altered total P, phytate and phytate-P contents in all varieties. Germination increased inorganic P contents but effected the highest percentage loss in residual organic P. Soybean contained considerable amounts of phytate anion and despite the reduction through processing, phytate content still exceeded the amount present in all varieties of raw lima beans.     

Changes of Selected Physical and Chemical Components in the Development of the Hard-to-Cook Bean Defect

The effects of storage temperature and humidity were monitored on several physical and chemical components of cowpeas and beans. Seeds stored at 29°C, 65% RH required prolonged cooking times; however, seeds stored in other conditions (5°C, 30% RH; 29°C 30% RH; and 5°C, 65% RH) maintained short, stable cooking times throughout storage. As cooking time increased, phytate, phytase activity, amylose solubility, high methoxyl pectin and protein solubility decreased. Solids leached during soaking and low methoxyl pectin increased as cooking time increased. These results were consistent with the proposed theory that the hard-to-cook defect involves interactions between phytate, minerals, and pectin. However, they did not eliminate possible roles of starch and protein solubility.     

Effect of content of protein, fat and modified starch on binding textural characteristics, and colour of comminuted scalded sausages

The effects of modified potato starch addition-distarch phosphate (ranging from 3.32 to 5.68%) and varying levels of fat and protein (ranging from 11.6 to 28.4% and from 7.32 to 10.68%, respectively)-on comminuted scalded sausage quality characteristics were investigated. Sausage quality was determined by measuring textural, hydration and colour characteristics. Starch addition favourably affected WHC and cooking loss and increased hardness of sausages processed. Fat reduction resulted in an increase in cohesiveness, gumminess and chewiness values, which were not overcome by the added starch. Lower fat contents were also accompanied by a significant reduction in the cooking yield and WHC. Protein content was the variable that most influenced WHC, hardness, gumminess and chewiness. Sausage colour parameters were affected only by varying fat levels (L*, a*, b*) and protein content (L*, a*).     

ENDOGENOUS PHYTATE-DEGRADING ENZYMES ARE RESPONSIBLE FOR PHYTATE REDUCTION WHILE PREPARING BEANS (PHASEOLUS VULGARIS)

The three dry nonprocessed bean varieties contain high amounts of phytate ranging from 9.3 to 15.9 μmol g^-1 dry basis, representing 85 to 89% of total myo-inositol phosphates, while the other myo-inositol phosphates were found only in small or trace amounts. Myo-inositol phosphate concentrations were not affected by soaking in water for 15h at 25C, whereas cooking resulted in a significant reduction in phytate content (16 to 24%) with a concomitant increase in the concentrations of the lower myo-inositol phosphates. The sum of phytate and myo-inositol pentakisphosphate after soaking and cooking represents about 93% of the amount in raw beans. Therefore, preparing of beans has only a limited effect on the content of myo-inositol phosphates with inhibitory effects on mineral absorption. Phytate-degrading enzymes (phytases) were identified as responsible for phytate removal during cooking, since a good correlation between phytase activity and phytate hydrolysis was observed.     

Volatile flavour profile changes in selected field pea cultivars as affected by crop year and processing

The objectives of this study were to evaluate the effect of cultivar, crop year and processing (dry milling, cooking and dehulling) on volatile flavour compounds of field peas using an optimised headspace-solid phase microextraction gas chromatography–mass spectrometry method. Significant differences in area counts of volatile compounds were observed between the different cultivars as well as in area counts of volatile compounds of each cultivar grown in different crop years. Results showed significant reduction in total area counts (TAC) of volatile compounds after cooking and dehulling the seeds. Major differences between whole seeds, cooked and dehulled seeds were found in aldehydes, alcohols, and ketones. Cooked–dehulled peas had the least TAC (7.83E±05) of the volatile compounds compared to the milled-whole peas (6.36E±06), cooked-whole peas (2.00E±06) and milled–dehulled peas (4.33E±06). The results suggest that volatile flavour compounds of different field peas were affected by the cultivar, crop year as well as processing conditions.