Rapid Rehydration Methods for Dried Beans

Rapid methods of rehydrating dried kidney, pinto or navy beans by soaking at 82°C or 93°C for 5, 10 or 30 min were compared to standard 18 hr soaking at ambient temperature. Canned beans processed 21 min at 121°C had higher drained weights and softer texture with fewer split beans than those processed 41 min at 116°C. Kidney, pinto and navy beans soaked 30 min at 82°C had higher drained weight than those soaked 30 min at 93°C. Hydration coefficient (2.07) of controls (18-hr soak) and beans soaked 82°C (1.94) or 93°C for 30 min were not different. Pre soaking 30 min at 82°C provided adequate rehydration prior to canning.     

Influence of Pre-Soaking on Black Bean Cooking Kinetics

Soaking of black beans (Phaseolus vulgaris L.) and the subsequent effect on cooking kinetics was investigated. Unsoaked beans and beans soaked in water or a salt combination solution were water cooked at temperatures of 90–135°C. Bean softening did not follow first order kinetics. Using D_T values (defined as cooking times necessary to reach an “eating-soft” texture: Instron puncture force of 150g), softening activation energies (Ea's) for unsoaked, water, and salt combination soaked were 19.1, 31.3, and 38.9 Kcal/mole, respectively. Z values were calculated as 17, 22 and 36C°, respectively. These relationships suggest ways of safely reducing cooking time and energy expenditures.     

The effect of thermal treatment on β‐glucosidase inactivation in vanilla bean (Vanilla planifolia Andrews)

The conditions for enzyme activity (pH and temperature) and kinetic parameters for the thermal inactivation of β‐glucosidase enzyme in vanilla beans have been investigated. The maximum enzyme activity was detected at pH 6.5 and 38 °C. The values obtained for V_max and K_m were 62.05 units and 2.07 mm, respectively. When hot water treatment (the most practical method of vanilla bean killing) was applied, β‐glucosidase treated at pH 6.0 and 60 °C for 3 min lost 51% of activity, while at 70 °C for 90 s the enzyme lost 60% of activity and at 80 °C for 30 s the enzyme lost 48% of its activity. When vanilla beans were cured in an oven at 60 °C for 36 to 48 h all β‐glucosidase activity was lost.     

Emulsifying Properties of Ethanol Soaked Soybean Flour

Soy flours prepared from soybeans soaked at 60°C for 6 hr in distilled water, 15% ethanol, or 0.1M NaHCO₃ in 15% ethanol were tested for their emulsifying capacity (EC) at pH 4.5, 6.5, and 9.0. At pH 4.5 and 6.5, there were no significant differences in EC among treatments; at pH 9.0, the EC was highest for soy flour from beans soaked in water, intermediate for flour from beans soaked in 15% ethanol, and lowest for flour from beans soaked in 0.1 M NaHCO₃ in 15% ethanol. The relationship between the amount of soluble protein and EC was inverse with EC decreasing sharply up to about 60 mg soluble protein/50 mL of flour dispersion. Photomicrographs of air incorporation during emulsion formation are presented.     

Water sorption and cooking time of red kidney beans (Phaseolus vulgaris L.): part I – Effect of freezing and drying conditions on water sorption and cooking time

Water sorption and cooking time of kidney beans were determined. The beans were manually harvested at 19.2 ± 0.1% moisture content and stored at ?20 and ?10 °C for about half a year. The beans were further dried at 30, 40 and 50 °C inside a thin‐layer drier for 7.5 h or under room conditions for 4 week. The freezing storage temperature before the beans were dried did not influence their cooking time and water sorption. The saturated kernel volumes decreased approximately 7% after drying. The beans decreased their sphericity during water sorption and had a larger swelling ratio in the thickness direction than in other directions. Lower initial moisture content, especially with a higher drying temperature, decreased water sorptivity and resulted in higher percentage of uncooked kernels if the beans were not soaked before cooking. However, there was no relationship between initial moisture content and uncooked percentage if the beans were soaked before cooking. High drying temperature resulted in hard‐to‐cook (HTC) phenomenon.     

Use of Hydration, Germination, and α-Galactosidase Treatments to Reduce Oligosaccharides in Dry Beans

ABSTRACT: This investigation was done to determine an energetically feasible method to reduce bean oligosaccharides (stachyose and raffinose) for large-scale bean flour production. Michigan black, red, and navy beans (all Phaseolus vulgaris ) were treated by α-galactosidase, germination, or hydration to determine treatment effects on stachyose and raffinose levels. Oligosaccharides were extracted with 70% (w/w) ethanol, and α-galactosidase was added to catalyze hydrolysis of the oligosaccharides. Enzyme treatment was for 1 h at ambient temperature (23°C). For germination, whole beans were incubated in a germinating chamber (100% humidity, 26.7°C) for 48 h. In hydration, whole beans were soaked in excess water at ambient temperature (23°C) for 5 h. Enzyme treatment resulted in 51%± 3.0%, 30%± 1.9%, and 46%± 1.9% reduction in total raffinose and stachyose for black beans, red beans, and navy beans, respectively. Germination treatment resulted in 61%± 12%, 61%± 1.9%, and 70%± 2.8% reduction in total raffinose and stachyose for black beans, red beans, and navy beans, respectively. Hydrated black beans showed a loss of 33%± 9.6%, whereas hydrated red and navy beans showed no reduction of oligosaccharides. Although germination showed the greatest reduction in bean oligosaccharides, this method may not be as cost-effective commercially as the enzyme treatment because of the time required for germination.     

Studies on the processing and properties of soymilk. II. Effect of processing conditions on the trypsin inhibitor activity and the digestibility in vitro of proteins in various soymilk preparations

Soymilks prepared from beans which had been soaked either in water or 0.4 M sodium carbonate solution for 24 h as a pretreatment were subjected to heat treatment under different conditions for varying lengths of time, to destroy the trypsin inhibitor activity. The rate of inactivation oftrypsia inhibitor in soy milks prepared from carbonate presoaked beans was faster than that of the water presoaked preparation when processed at 98°C and this effect was primarily associated with the change that occurred in the pH of the former system; The effect of alkaline pH's at 98°C on the inactivation of trypsin inhibitor was examined and it was found that the rate of inactivation was changed from zero order at pff 6.8 to first-order kinetics at pH 9.9. Regression equation relating pH of the system and time of heating at 98°C for 100% destruction of the inhibitor activity is presented. This effect of pretreatment was eliminated when both milks were processed at 115°C in cans because of the constancy of pH under these conditions. The influence of heat processing conditions on the enzymic digestibility of proteins in both soymilks was also studied. The pepsin digestion showed no significant differences between milks prepared from the water and the carbonate presoaked soybeans, and was highest in milks which had not been heat treated. With trypsin the digestibility increased with the degree of heal treatment up to the point where the trypsin inhibitor was destroyed, after which further heating resulted in lower digestibilities. A 19% increase in digestibility by trypsin was observed in the milk prepared from carbonate presoaked beans when compared with that from water presoaked beans and after both milks had been heated at 98°C for just sufficient time to destroy the trypsin inhibitor. When the milk prepared from water presoaked beans was autoclaved at 115°C to the same end point, its digestibility increased but it was still about 6% lower than that of the milk prepared by alkali presoaking method and processed at 98°C. The digestibility of casein using pepsin under the conditions used was lower than that of both soymilks. When trypsin was used the digestibility of casein was approximately the same as that of the adequately processed soymilk from carbonate presoaked soybeans or the autoclavtd soymilk from water presoaked beans. Other effects of using a carbonate presoaking treatment far the production of soymilk have also been discussed.     

Nutritional assessment of protein from beans (Phaseolus vulgaris L) processed at different pH values,in growing rats

The effect of the commonly used processing techniques of soaking (at different pH values) and cooking on the digestive and metabolic utilisation of protein from common beans (Phaseolus vulgaris L) in growing rats was studied. Before the cooking step, beans were soaked in solutions of pH 2.6, 5.3 or 8.4. Analyses of beans soaked at moderately acid pH (5.3) showed a significant increase in essential amino acids, especially cysteine. Food intake and growth indices were also dependent on pH. All indices were better in animals fed with beans soaked in a basic pH solution than when an acid soaking solution was used. In contrast with the findings expected on the basis of the chemical analysis of protein composition of the food, the worst results for food intake and growth were found in rats fed with beans soaked at pH 5.3. There were no significant differences in apparent digestibility coefficient between different groups of animals. The highest metabolic utilisation of protein (balance) was found in animals fed with beans soaked in a basic solution; however, the values were insufficient to account for the faster rate of growth in this group. The better growth rate was probably due to the improved utilisation of carbohydrates in beans soaked in the basic pH (8.4) solution. © 2001 Society of Chemical Industry     

The impact of processing on phytic acid,in vitro soluble iron and Phy/Fe molar ratio of faba bean (Vicia faba L.)

BACKGROUND: Faba bean is one of the important legumes in Asian countries. It is also a major source of micronutrients in many rural areas. Unfortunately, the bioavailability of iron from faba bean is low because it is present as an insoluble complex with food components such as phytic acid. The influence of soaking, germination and fermentation with the expectation of increasing the bioavailability of iron was investigated. RESULTS: Fermentation treatments were most effective in decreasing phytic acid (48–84%), followed by soaking at 10 °C after preheating (36–51%). Steeping faba beans for 24 h at 25 °C had the least effect on the removal of phytic acid (9–24%). With increased germination time at 30 °C, phytic acid progressively decreased from 9 to 69%. Most wet processing procedures, except soaking after wet preheating, caused losses of dry matter and iron (8–15%). In vitro iron solubility, as a percentage of total iron in soaked faba bean after dry preheating, was significantly higher than in raw faba bean (P < 0.05). Fermentation and germination did not have significant effects on the solubility of iron. CONCLUSION: The expected improvement of iron bioavailability levels due to lower phytic acid was not confirmed by increasing levels of in vitro soluble iron. Soaking, germination and fermentation can decrease phytic acid in faba bean. However, results from in vitro solubility measurement of iron showed little improvement of iron bioavailability in fermented and germinated faba beans over untreated raw faba beans (P < 0.05). It seems that componets of dietary fibre other than phytic acid are more important in binding iron. Probably, a complex association between dietary fibre and iron is the reason for the poor bioavailability of iron in faba bean. Copyright © 2009 Society of Chemical Industry     

The peroxidase enzyme activity of some vegetables and its resistance to heat

The peroxidase enzyme activities of some fresh vegetables (cabbage, leeks, carrot, spinach, celery, squash, potatoes, onions and green beans) were determined. The peroxidase activities of cabbage and green beans were high. Onions showed very little peroxidase activity. The vegetables were blanched in hot water at 75°G, 85° and 95°C. Peroxidase inactivation was faster at the higher temperature blanch. Blanching of green beans, potatoes and squash at 75°C for 30 min was not sufficient for complete inactivation of peroxidase enzyme. Peroxidase enzyme inactivation was also affected by the type of vegetable and the size of vegetable pieces.     

Proximate compositions, pasting and rheological properties of mumu– a roasted maize meal

Genetically improved maize variety (TZRS‐W) grains were used to produce mumu– a roasted maize meal. The grains were divided into six treatment groups namely: non‐soaked, non‐cooked (NSNC); non‐soaked, cooked (NSC); soaked, non‐cooked (SNC); soaked, cooked (SC); germinated non‐cooked (GNC); and germinated, cooked (GC). Each group was roasted in the oven at 150 °C for 1 h to produce mumu. No significant differences (P ≤ 0.05) were found in the protein, fat, ash, fibre and carbohydrate contents of the different products. Soaking and germination without cooking resulted in lower breakdown viscosities of the products. The peak viscosity (20.17 Rapid Visco Unit (RVU)) and final viscosity (28 RVU) of the GNC samples were significantly higher (P ≤ 0.05) than the corresponding values (5.17–7.25 RVU) of the NSNC, NSC, SNC, SC and GC products. No significant differences (P ≤ 0.05) were found in the pasting temperatures (63.40–64.85 °C) between all the six groups. Germination for 24 h without cooking may yield poor quality products with low nutrient density.     

GROWTH OF STAPHYLOCOCCUS AUREUS S-6 AND YERSINIA ENTEROCOLITICA CDC A2635 IN COW, SOY AND WINGED BEAN MILKS

The two common foodborne pathogens, Staphylococcus aureus S-6 and Yersinia enterocolitica CDC A2635 were inoculated into whole cow, soy and winged bean milks and incubated at three different temperatures (10°, 25°, 37°C) to evaluate the potential for their growth. The legume milks were prepared by a hot grind method from either whole soybeans (Essex variety) or whole winged beans (Chimbu variety). In general, both foodborne pathogens grew well in all test media. However, S. aureus incubated at 10°C for 120 h, and Y. enterocolitica incubated at 37°C for 48 h were the only two conditions in which less than 10⁸ cells/mL were obtained.     

A Kinetic Interpretation of Textural Changes in Black Beans During Prolonged Storage

Control and roasted (80°C), dry black beans (Phaseolus vulgaris) were stored for 9 months at 8, 10, 12, and/or 14% moisture content and 8.5°, 25°, and 40°C. Similarly, beans heated in a solid-to-solid roaster to 51°, 61°, 72.3°, 80°, 85.5°, 89.5°, lO1°, and 111°C were maintained at 8% moisture and 25°C. Final hardness increased with moisture content and temperature. Hardening at 8.5° and 25°C proceeded initially almost linearly reaching a constant value after 4 to 6 months while at 40°C it was sigma-shaped. A pseudo-zero order kinetic model fitted for initial rates had an activation energy of 6–11.8 kcal/mol. The hardening rate at 25°C paralleled the shape of the sorption isotherm.     

Electron spin resonance studies on γ-irradiated coffee bean parts

Summary Using electron spin resonance (ESR) free radicals, present naturally or formed after γ‐irradiation of parts of coffee bean, were examined by entrapping the sample in potassium chloride powder in ESR quartz tubes. The ESR signal at g=2.002 was more prominent in the spermoderm than in the whole seed portion of the coffee beans. The γ‐irradiation of coffee beans with doses of 5 or 10 kGy, normally used for decontamination, resulted in a dose‐dependent increase of a signal at g=2.002 which was accompanied by a weak triplet (a_H c. 3.0 mT), and which was also more prominent in the spermoderm. While short‐term storage (24 h at 25 ± 0.5 °C) of irradiated beans resulted in a substantial loss of signal at g=2.002, annealing at 50 ± 0.5 °C for 16 h increased this signal intensity in greater proportion than caused by irradiation alone, suggesting that generation of free radicals in the two varieties of coffee beans is not unique to the irradiation processing alone.     

Denaturation Time and Temperature Effects on Solubility, Tensile Properties, and Oxygen Permeability of Whey Protein Edible Films

ABSTRACT Whey protein film solubility decreased as film-forming solution heating time and temperature increased. No differences were observed in solubility between films soaked in water at 25 °C for 24 h and 100 °C for 4 min. However, the degree of swelling was significantly larger for films soaked at 100 °C. Films became stiffer, stronger and more stretchable as film-forming solution time and temperature were increased. Oxygen permeability (OP) was lower for films made from heat-denatured whey protein than for films made from native whey protein. Results suggest that an increase in covalent cross-linking, as heat denaturation of the whey protein increases, is accountable for film water insolubility, higher tensile properties and lower OP.     

Improved Fermentation of Cocoa Beans with Enhanced Aroma Profiles

The cocoa (Theobroma cacao) fermentation was carried out using starter consortia of Saccharomyces cerevisiae, Lactobacillus plantarum, and Acetobacter aceti with 10% inoculum. The fermented beans were soaked with sterile water (1:3 wt/v) for the duration of 1, 3, and 5 h. The treated beans were dried to the moisture content of 7 ± 1%. The samples were then roasted, ground and subjected to steam distillation. The volatiles were extracted and identified using GC-MS. The samples soaked for 1 h scored 100% cut score along with 0.85% fermentation index. The volatile and non-volatiles were associated with beans treated in water after fermentation. Volatile compounds were classified as esters, alcohols, acids, aldehydes, ketones, pyrazines, hydroperoxides, and hydrocarbons. Most of the oxygenated aliphatic compounds and aromatics were potentially derived via an acetic acid and shikimic acid pathways, respectively. Untreated cocoa beans contained 12 sesquiterpene hydrocarbons potentially derived through the mevalonic acid pathway and contributed to harsh notes. Also, these metabolites were completely absent in the treated samples indicating depletion while soaking. Thus, the treated samples (1 h) had enhanced quality with high flavor notes with 8.5 rating on sensory evaluation. Thus, these soaking treatments with fermentation lead to improvement of flavor profiles which confers improved cocoa quality.     

Purification of a cyanide-sensitive superoxide dismutase from soya beans: A food-compatible enzyme preparation

A method of purifying superoxide dismutase (SOD; EC 1.15.1.1), free from lipoxygenase (EC 1.13.11.12) and catalase (EC 1.11.1.6), from ethanol-treated soya beans is described, Preparations with the highest activity were obtained from new season's beans. Although not homogeneous by electrophoretic analysis, the preparation was 300-fold purified. The enzyme has a molecular weight of 36 300 and a subunit molecular weight of 18 000. Its sensitivity to cyanide suggests that it is a typical cupro-zinc SOD. Isoelectric focusing showed the presence of three separate charged species with isoelectric points of pH 4·73 (the major species), 4·55 (the minor species), and 4·37. The enzyme withstands 45 min at 65°C without loss of activity, and loses only half its activity in 30 min at 75°C at pH values between 5 and 8. Severe losses in activity at pH 4 and below are observed at 75°C. The enzyme can be stabilised for storage at 4°C in 60% (v/v) glycerol.     

Freezing, thawing and cooking effects on quality profile assessment of green beans (cv. Win)

Results are presented of the effect of freezing followed by thawing (air and water immersion, both at environmental temperature) and cooking (traditional boiling in a covered pot) on quality profile (in terms of objective texture, colour, chlorophylls and pheophytins and sensory attributes) and structure of green beans (cv. Win). Freezing was carried out at three different rates by forced convection with liquid nitrogen vapour. Kramer shear cell (KSC) and Warner–Bratzler (WB) tests were used for objective assessment of the texture. The highest parameter values occurred in beans frozen at the highest rate and air-thawed at the slowest rate. Also, minimum alteration of the rheological behaviour of cooked beans was achieved by freezing at the highest rate. The best parameter for assessing the texture of frozen green beans after thawing and cooking was the Warner–Bratzler slope (S _WB). Coefficients of softening estimated for S _WB in the thawed beans showed that the texture of the beans frozen at −24 °C was almost four and almost five times softer than that of the beans frozen at −70 °C, for air and water thawing respectively. Frozen and thawed green beans were darker than fresh control, whereas freezing prior to cooking produced lighter-coloured beans than direct cooking. The freezing rate affected colour parameters differently depending on the process that followed. When beans were thawed, increasing the freezing rate produced lighter-coloured beans, whereas when beans were cooked, increasing the rate produced darker-coloured beans. No difference was found in sensory assessments between cooked samples frozen at −24 °C, −35 °C and −70 °C, which probably reflects the panellists' mixed preferences for quickly and slowly frozen samples. Scanning electron microscopy (SEM) revealed different degrees of mechanical damage to tissue structure, which accounted for the rheological behaviour of the beans.     

Thermal stability of black turtle soup bean (Phaseolus vulgaris) lectins

A method for determining the thermal stability of porcine thyroglobulin (PTG)-binding lectins in whole black turtle soup beans (Phaseolus vulgaris L) is described. The procedure utilises PTG-Sepharose affinity chromatography and the Folin-Ciocalteau protein assay. The majority of lectin activity in whole black turtle soup beans was destroyed by heating presoaked beans at 97.8°C for 10 min whereas unsoaked beans required 20 min of heat treatment at 97.8°C. Residual lectin activity was eliminated by thermally processing the presoaked and unsoaked beans for 25 and 50 min at 97.8°C, respectively. Thermal inactivation of the lectin in the whole seed is a biphasic, first-order reaction mechanism. Lectin-rat intestinal epithelial cell binding studies indicated the presence of a second lectin in the BTS albumin protein fraction. The lectin lacked an affinity for PTG and was inactivated by heating unsoaked whole beans for 50 min at 97.8°C.     

In vitro starch digestibility of fresh and sun‐dried faba beans (Vicia faba L.)

Fresh and sun‐dried faba beans (Vicia faba L.) were cooked, stored for various times at 4 °C and analysed for available starch (AS), resistant starch (RS) and fibre‐associated resistant starch (FARS) contents as well as α‐amylolysis. Fresh beans required a shorter cooking time (25 min) than dried beans (158 min). Cooked fresh faba beans had a higher AS content than cooked dried faba beans. The AS content in both decreased during cold storage, with fresh beans showing a smaller decrease than dried beans with increasing storage time. Cooked fresh faba beans also had a higher total RS content than cooked dried faba beans, although a greater increase in RS content was recorded in the latter upon storage. Starch retrogradation was more prominent in cooked dried faba beans than in cooked fresh faba beans, as indicated by the consistently higher FARS content. The α‐amylolysis rate decreased with increasing storage time, i.e. long‐stored (72 h) cooked faba beans exhibited slower starch digestion, and differences were recorded between fresh and dried beans. The predicted glycaemic index ranged between 60.9 and 58.0% for cooked fresh faba beans and between 57.9 and 55.8% for cooked dried faba beans, which is suggestive of slow glucose release from starch in faba beans. Copyright © 2007 Society of Chemical Industry