Enzymatic hydrolysis of hard‐to‐cook bean (Phaseolus vulgaris L.) protein concentrates and its effects on biological and functional properties

Inadequate postharvest handling and storage under high temperature and relative humidity conditions produce the hard‐to‐cook (HTC) defect in beans. However, these can be raw material to produce hydrolysates with functional activities. Angiotensin I‐converting enzyme (ACE) inhibitory and antioxidant capacities were determined for extensively hydrolysed proteins of HTC bean produced with sequential systems Alcalase‐Flavourzyme (AF) and pepsin–pancreatin (Pep‐Pan) at 90 min ACE inhibition expressed as IC₅₀ values were 4.5 and 6.5 mg protein per mL with AF and Pep‐Pan, respectively. Antioxidant activity as Trolox equivalent antioxidant capacity (TEAC) was 8.1 mm  mg^?1 sample with AF and 6.4 mm  mg^?1 sample with Pep‐Pan. The peptides released from the protein during hydrolysis were responsible for the observed ACE inhibition and antioxidant activities. Nitrogen solubility, emulsifying capacity, emulsion stability, foaming capacity and foam stability were measured for limited hydrolysis produced with Flavourzyme and pancreatin at 15 min. The hydrolysates exhibited better functional properties than the protein concentrate.     

Hard‐to‐cook tendency of chickpea (Cicer arietinum L) varieties

Chickpeas (Cicer arietinum L) develop the hard‐to‐cook (HTC) defect during storage at high temperatures (>25 °C) and high relative humidities (RH>65%). The objective of this work was to assess the tendency of chickpea varieties to become HTC. Three samples of chickpeas (Surutato 77, Mocorito 88 and Blanco Sinaloa 92) were grown under irrigation conditions. Two hardening procedures were used: (1) storage hardening—samples were stored at 33–35 °C and 76% relative humidity for 160 days; (2) chemical hardening—materials were soaked in 0.1 M acetate buffer (pH 4.0) at 37 °C for 1–7 h. The cooking time curves generated by chemical hardening had shapes similar to those obtained by storage hardening; both procedures were equally capable of discriminating chickpea varieties based on their susceptibility to develop the HTC condition. Chemical hardening might be useful for screening new chickpea varieties; its advantage over the storage method is its rapidity. © 2001 Society of Chemical Industry     

Chemical and microstructural evaluation of ‘hard‐to‐cook’ phenomenon in legumes (pinto bean and small‐type lentil)

Some physicochemical and microstructural characteristics of hard‐to‐cook (HTC) and easy‐to‐cook (ETC) pinto beans and small‐type lentils were compared. The development of HTC seeds was monitored over 6 months for changes in physicochemical properties. Results indicated that hardness, extent of water absorption and solid loss of HTC legumes were, respectively, 21–97%, 7–72% and 62–236% higher than those of ETC legumes. In addition, darkening of HTC beans and lentils was significantly higher than those of ETC ones. Scanning electron microscope observations indicated deteriorations in cytoplasmic contents of cotyledon cells of hard seeds. Phytic acid and total phenolic contents were, respectively, decreased 36–61% and 43–61% during storage, whereas hardness of seeds was increased 3–6 times. The soaking of hard seeds in sodium solutions resulted in the improvement in legume texture.     

Phytase–phytate–pectin hypothesis and quality of legumes cooked in calcium solutions

Hard‐to‐cook and easy‐to‐cook bean and lentil seeds were boiled in water containing calcium ions at concentrations of 0, 40, 80, 120 and 160 mg L^?1 and their texture and concentration of phytate and various peptic compounds were measured. In order to minimise matrix effects, hard‐to‐cook seeds were prepared from easy‐to‐cook seeds by soaking them at 50 °C. It was found that, as calcium ion concentration increased, phytate concentration decreased and seed hardness increased. Also, during soaking and cooking, phytate and peptic compounds were leached into the water. Losses were larger for hard‐to‐cook seeds than for easy‐to‐cook seeds. These results are consistent with the proposed theory that the formation of hard‐to‐cook legume seeds involves an interaction among divalent cations, phytate and peptic compounds, which is based on the phytase–phytate–pectin hypothesis. Copyright © 2007 Society of Chemical Industry     

Comparison of post‐germination mobilization of cell wall polysaccharides and non‐cell wall carbohydrates in soybean (Glycine max L.) cotyledons

BACKGROUND: In previous research, we demonstrated that cell wall polysaccharide (CWP) levels of soybean (Glycine max L.) cotyledons are negatively correlated with the sum of seed oil and protein content. Although the results suggest that reducing cotyledon CWP levels would be desirable, it is not known whether CWP are mobilized during early seedling growth and, if so, to what extent mobilization contributes to seed reserves. RESULTS: Ungerminated (dry) seeds contained equivalent amounts [approximately 20 mg (cotyledon pair)^?1] of non‐cell wall carbohydrates (NCWC) and CWP. Galactose and arabinose accounted for 47% of total CWP in cotyledons of dry seeds. Measured 14 days after planting (DAP), the levels of NCWC and CWP were reduced 98% and 34%, respectively, in cotyledons of seedlings grown under a 16‐h photoperiod. Measured 14 DAP, greater than 85% of cotyledon cell wall galactose plus arabinose was mobilized. The transformation of the cotyledon to a photosynthetic organ was associated with restructuring of the cell wall involving increases in uronic acids, glucose and rhamnose. CONCLUSION: CWP of soybean cotyledons are modified during early seedling growth due to mobilization and cell wall restructuring triggered by light. The amount of carbon mobilized makes only a small contribution to total cotyledon reserves. Published 2009 by John Wiley & Sons, Ltd.     

Gamma irradiation of cowpea (Vigna unguiculata L. Walp) seeds: effect on colour,cooking quality and pasting characteristics

Cowpea seeds were treated to various gamma irradiation doses, and their colour, cooking quality and pasting properties studied. Irradiation at 50 kGy resulted in significant browning (indicated by decreases in L colour value) of cowpea seeds. At 2 and 10 (but not at 50) kGy, irradiation led to significant reduction in cooking time of cowpea seeds possibly through irradiation‐induced degradation of starch and pectic substances (indicated by decreases in peak and final viscosities) leading possibly to enhanced heat and mass transfer within the seed cotyledon and cell wall, respectively. At 50 kGy, the cooking time of cowpea seeds was prolonged significantly owing possibly to extensive polymer cross‐linking occurring within the seeds at this high dose. Splitting of cowpea cotyledons during cooking decreased significantly at 50 kGy, but was unaffected at 2 and 10 kGy. Irradiation resulted in significant leaching of nutrients from cowpea seeds during cooking in a dose‐dependent manner.     

Comparison of physicochemical properties,antioxidant and metal‐chelating activities of protein hydrolysates from Phaseolus lunatus and hard‐to‐cook Phaseolus vulgaris

Limited and extensive hydrolysates were obtained from Phaseolus lunatus (LHl and EHl) and hard‐to‐cook Phaseolus vulgaris (LHv and EHv) using the enzymes Flavourzyme^®, Alcalase^®, Pancreatin^® and a sequential Pepsin^®–Pancreatin^® system. Degrees of hydrolysis varied from 8.32% to 31.60%. SDS‐PAGE of extensive hydrolysates showed molecular weights smaller than limited hydrolysates. Differential scanning calorimeter (DSC) analysis of LHl and EHl revealed the presence of two endothermic transitions; LHv and EHv had only one. LHv presented a higher content of hydrophobic amino acids whose surface hydrophobicity was 12.17. Functional properties such as nitrogen solubility, foaming capacity and emulsifying activity index in LHv were better than LHl at different pH evaluated. However, the latter showed better foaming stabilities. Amino acids such as His, Tyr, Trp and Arg were observed in greater amounts in both extensive hydrolysates. 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical‐scavenging and metal‐chelating activities in EHv and EHl increased significantly compared to the source material.     

Control of Listeria monocytogenes Contamination in Ready‐to‐Eat Meat Products

The ubiquitous nature of Listeria monocytogenes and its ability to grow at refrigerated temperature makes L. monocytogenes a significant threat to the safety of ready‐to‐eat (RTE) meat products. The contamination by L. monocytogenes in RTE meat primarily occurs during slicing and packaging after cooking. The effectiveness of post‐package decontamination technology such as in‐package thermal pasteurization, irradiation, and high‐pressure processing are discussed. Formulating meat products with antimicrobial additives is another common approach to control L. monocytogenes in RTE meat. Irradiation is an effective technology to eliminate L. monocytogenes but can influence the quality of RTE meat products significantly. The effect of irradiation or the combination of irradiation and antimicrobials on the survival of L. monocytogenes and the quality of RTE meat is discussed.     

Changes in the biochemical and functional properties of the extruded hard‐to‐cook cowpea (Vigna unguiculata L. Walp)

Changes in the biochemical and functional properties of the hard‐to‐cook cowpea bean after treatment by the extrusion process are reported. The extrusion was carried out at 150 °C, with a compression ratio screw of 3:1, a 5‐mm die, and a screw speed of 150 r.p.m. The extrusion caused the complete inactivation of the α‐amylase and lectin and it also reduced the trypsin inhibitor activity (38.2%) and phytic acid content (33.2%). The functional properties were also modified by the process, an increase of 2.5 times in the water absorption index and 3.1% in the water solubility were observed. The digestibility of the hard‐to‐cook flour of the cowpea bean was improved after the extrusion, with a 55.9% increase in protein digestibility and a 5.9% increase in starch digestibility.     

Effects of ionising irradiation on quality and sensory attributes of ready‐to‐eat dry fermented sausages enriched with folic acid

Dry fermented sausages have been manufactured with different concentrations of folic acid (FA) (0.6, 1.2 and 2.4 mg per 100 g of original mixture). Then, they were prepared as ready‐to‐eat meat products by using E‐beam radiation (2, 3 and 4 kGy) to increase their safety. The stability of this vitamin as well as the physico‐chemical properties, microbiological counts, colour, texture and sensory properties of the sausages was studied after irradiation. The more important changes were observed in hardness, which increased with increasing FA amount; in contrast, colour was similar in all batches, independently of FA concentration or irradiation doses applied. The sensory properties of these products were judged acceptable to tasters, although significant differences were observed between the taste of nonirradiated and irradiated samples with 3 kGy. The ionising treatment caused a decrease of 15–29% in the FA content only at the highest dose (4 kGy). Despite this loss, this new product is suitable for assuring the daily intake of FA recommended as healthy (400 μg).     

Effects of gamma‐irradiated soybean pod extract on oxidative stress,cancer cell viability,and tyrosinase inhibition

Soybean pods contain abundant dietary fiber and phytochemicals, including phenolic compounds. However, few bioactivity studies have been conducted using soybean pods, while soybean leaves, and seeds have been well characterized. In this study, the effect of gamma irradiation on the physiological properties of soybean pod extract (SPE) was investigated. SPE was irradiated at 0, 5, 10, and 20 kGy, and the phenolic compound concentration and antioxidant activity were investigated. The total phenolic compounds were increased and total flavonoids were decreased as the irradiation dose increased. Antioxidant activity, which was measured using the 2,2‐diphenyl‐1‐picrylhydrazyl, 2,2′‐azino‐bis‐3‐ethylbenzothiazoline‐6‐sulphonic acid, and 2‐thiobarbituric acid reactive substances assays, improved as the irradiation dose increased. In addition, cancer cell viability, and tyrosinase activity were reduced by gamma irradiation. These results show that soybean pods can be utilized as functional food materials after gamma irradiation.

Practical applications

Gamma irradiation modified the chemical composition of soybean pod extract (SPE). Such irradiation improved the antioxidant, anti‐pigmentation, and anti‐carcinogenesis effects compared to those of control SPE. Therefore, this material, previously considered a byproduct of soybean processing, can be used as a functional food to prevent such disorders as oxidative damage, cancer, and hyperpigmentation.     

Effect of gamma‐ray irradiation on the physicochemical properties of flour and starch granule structure for wheat

Effect of gamma irradiation on the physicochemical properties of flour and starch granule structure of wheat was compared to non‐irradiated wheat. The moisture content of wet gluten and titratable acidity of wheat flour were significantly affected by gamma irradiation. This treatment also destroyed the starch granules of wheat grain and their breakage augmented as the dose of gamma irradiation increased, apparently resulting in the increase of small starch granules. Probably, these results were due to the disruption of large molecule, such as proteins, lipids and starch. The irradiated wheat flour for RVA pasting properties (flour viscosity) was also evaluated. Besides the difference in RVA profile, starch pasting curves showed a considerable decrease for six main parameters as gamma irradiation dose at different velocity increased.     

Effects of chloride,thiocyanate and sulphate salts on β‐lactoglobulin–pectin associative complexes

Protein–polysaccharide complexes are used to improve protein stability and encapsulate high‐value ingredients, yet the influence of different salts on their formation has not been investigated. Using light scattering and turbidimetry, effects of chloride, sulphate and thiocyanate salts on β‐lactoglobulin and pectin complexes (protein/pectin ratio = 2:1 and 4:1) were determined in relation to effects of pH and ionic strength. Effects of anions on complex formation were significant at 25 mmol kg^?1 added ionic strength. Cation effects were not significant. At 100 mmol kg^?1 ionic strength, pH of complex formation increased with sulphate salts (pH 5.1) relative to chloride and thiocyanate salts (pH 4.9), while pH of coacervation increased with sulphate salts (pH 4.7) and decreased with thiocyanate salts (pH 4.4) relative to chloride salts (pH 4.6). Pure β‐lactoglobulin stability was otherwise reduced with thiocyanate salts below pH 5, implying a significant effect of pectin interactions.     

Diverse metabolism of cell wall components of melting and non‐melting peach genotypes during ripening after harvest or cold storage

The mode of change in a range of physiological, physicochemical and biochemical parameters during fruit ripening between distinct peach genotypes (Prunus persica L. Batsch) after cold storage for up to 4 weeks was determined. The nectarine cultivar ‘Caldesi 2000’ was selected as a genotype with melting flesh (MF) characteristic (fruits characterized by extensive flesh softening during ripening) and the cultivar ‘Andross’ as a genotype with non‐melting flesh (NMF) characteristic (fruits characterized by limited flesh softening during ripening). Flesh firmness, ethylene production, physicochemical and biochemical properties of the cell wall were determined and significant differences between the fruits of the two genotypes were recorded. Fruits of the NMF genotype were characterized by higher tissue retention and ethylene production during their ripening, higher content of uronic acids, as well as higher capacity for calcium binding in the water‐insoluble pectin fraction compared with fruits of the MF genotype. Additionally, the ripening of MF‐type fruits was characterized by higher losses of neutral sugars, especially those of arabinose and galactose than the NMF‐type fruits and these losses were more intense after extended cold storage periods. In fruits of the NMF genotype the decreased activity of pectin methyl esterase (PME) combined with higher levels of calcium in the water‐insoluble pectin fraction possibly provided less substrate for polygalacturonase (exo‐, endo‐PG) activity and less solubility of cell wall pectin compared with fruits of the MF genotype. Overall, the data indicate the existence of a wide range of diverse metabolic pathways during fruit ripening of fresh fruits with MF and NMF characteristics. Copyright © 2005 Society of Chemical Industry     

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.     

Effects of Antimicrobial Coatings and Cryogenic Freezing on Survival and Growth of Listeria innocua on Frozen Ready‐to‐Eat Shrimp during Thawing

Foodborne pathogens such as Listeria monocytogenes could pose a health risk on frozen ready‐to‐eat (RTE) shrimp as the pathogen could grow following thawing. In this study, antimicrobial‐coating treatments alone, or in combination with cryogenic freezing, were evaluated for their ability to inhibit the growth of Listeria innocua, a surrogate for L. monocytogenes, on RTE shrimp. Cooked RTE shrimp were inoculated with L. innocua at 3 population levels and treated with coating solutions consisting of chitosan, allyl isothiocyanate (AIT), or lauric arginate ester (LAE). The treated shrimp were then stored at –18 °C for 6 d before being thawed at 4, 10, or 22 °C for either 24 or 48 h. Results revealed that antimicrobial coatings achieved approximately 5.5 to 1 log CFU/g reduction of L. innocua on RTE shrimp after the treatments, depending on the inoculated population levels. The coating‐treated shrimp samples had significantly (P < 0.05) less L. innocua than controls at each thawing temperature and time. Cryogenic freezing in combination with coating treatments did not achieve synergistic effects against L. innocua. Antimicrobial coatings can help to improve product safety by reducing Listeria on RTE shrimp.     

Effects of electron‐beam irradiation on physicochemical properties of starches separated from stored wheat

Effects of electron‐beam irradiation (0, 1.0, 2.7, and 4.4 kGy) on physicochemical properties, MW distribution as well as microstructure of starches separated from electron‐beam irradiated and stored wheats were investigated by differential scanning calorimeter (DSC), SEM, and static multi‐angle laser light scattering (MALLS). The profiles of starch viscosity illustrated that peak, hot paste, cold paste, and setback were considerably decreased with increasing irradiation dose. The DSC pattern indicated that the electron‐beam irradiation caused a slight decrease in gelatinization temperature. SEM results showed that on the surfaces of a few starch granules fissures appeared and that they become rough when the irradiation doses reached 4.4 kGy. Damaged starch (DS) contents analysis suggested that the DS increased from 5.33 to 7.38% as the dose increased from 0 (control) to 4.4 kGy. HPSEC measurement showed that the starch molecule were gradually degraded due to the electron‐beam irradiation treatment, and the molar mass of wheat starches decreased by one order of magnitude when the irradiation doses reached 4.4 kGy.     

Effect of pectin on plasma lipids and caecal enzyme activity in rutin‐supplemented mice

BACKGROUND: Few previous reports have considered the effects of dietary fibre on the plasma lipids and caecal enzyme activity of mice fed a rutin‐supplemented diet. This investigation studied the effects of pectin on the plasma lipids and caecal enzyme activities of mice fed a diet supplemented with the quercetin glycoside rutin. RESULTS: Male mice were randomly divided into two groups and fed either a pectin–rutin (PR) diet or a cellulose–rutin (CR) diet for 14 days. Plasma cholesterol and triglyceride concentrations and caecal β‐glucosidase and β‐glucuronidase activities were measured. The plasma cholesterol and triglyceride concentrations were significantly higher in the CR diet group, as were the caecal β‐glucosidase and β‐glucuronidase activities. The caecal β‐glucuronidase/β‐glucosidase activity ratio was significantly higher in the PR diet group, indicating differences in the metabolic activity of the intestinal flora. CONCLUSION: The PR diet greatly affected the caecal enzyme activities. A pectin diet supplemented with the quercetin glycoside rutin might affect the lipid metabolism and metabolic activity of the intestinal flora. The plasma lipid‐lowering effects of the PR diet might have been partially caused by the metabolic actions of the intestinal gut flora. Copyright © 2009 Society of Chemical Industry