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.     

Inactivation of peroxidase and lipoxygenase in carrots, green beans, and green peas by combination of high hydrostatic pressure and mild heat treatment

The efficiency of high hydrostatic pressure (HHP) with the combination of mild heat treatment on peroxidase (POD) and lipoxygenase (LOX) inactivation in carrots, green beans, and green peas was investigated. In the first part of the study, the samples were pressurized under 250–450 MPa at 20–50 °C for 15–60 min. In the second part, two steps treatments were performed as water blanching at 40–70 °C for 15 and 30 min after pressurization at 250 MPa and 20 °C for 15–60 min. Carrot POD was decreased to 16% residual activity within the first 30 min at a treatment condition of 350 MPa and 20 °C and then it decreased to 9% at 60 min. When the carrots were water blanched at 50 °C for 30 min after HHP treatment of 250 MPa at 20 °C for 15 min, 13% residual POD activity was obtained. For green beans, the most effective results were obtained by two steps treatment and approximately 25% residual POD activity was obtained by water blanching at 50 °C for 15 min after pressurization at 250 MPa and 20 °C for 60 min. An effective inactivation of POD in green peas was not obtained. For carrots, LOX activity could not be measured due to very low LOX activity or the presence of strong antioxidants such as carotenoids. After pressurization at 250 MPa and 20 °C for 15 or 30 min, water blanching at 60 °C for 30 min provided 2–3% residual LOX activity in green beans. The treatment of 250 MPa for 30 min and then water blanching at 50 °C for 30 min provided 70% LOX inactivation in green peas.     

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.     

Processing to Improve Quality of Dehydrated Precooked Pinto Beans

The firmness of precooked and rehydrated beans after soaking in water at 30°C/2 hr and 82°C/1 hr was lower than that after soaking at 82°C/1 hr or 22°C/12 hr. The 22°C/12 hr soaking yielded the lowest butterflying (8.0%). Steam precooking at 100°C/1 hr produced less splitting, lighter color, and firmer texture than pressure precooking. High initial humidity dehydration reduced splitting. Beans after soaking at 30°C/2 hr and 82°C/1 hr, precooking at 100°C/1 hr, and dehydrating at 65°C/6 hr with initial 95% relative humidity were better regarding firmness, butterflying (11.6%), and moisture content (10.4%).     

Evaluation of the Hemagglutinating Activity of Low-temperature Cooked Kidney Beans

Methodology was developed that allowed sensitive measurement of phytohemagglutinin (PHA), the lectin of kidney beans. Trypsinated porcine red blood cells were treated with saline extracts of kidney beans, incubated, and the nonagglutinated cells were quantitated using a Coulter Counter. This hemagglutination activity (HA) assay was then used to monitor the PHA in cooked kidney beans. The thermal treatment (minutes @°C) required to reduce HA by 1 log cvcle was: 12 @ 100°C: 62 @ 93°C: 136 @ 88°C: 160 @ 82°C. Beans were prepared in commercially available low-temperature cookers and evaluated for tenderness and residual hemagglutinating activity.     

Amino Acid Composition and Some Antinutritional Factors of Cooked Faba Beans (Medammis): Effects of Cooking Temperature and Time

Easy-and hard-to-cook bean seeds were cooked by different heat treatments (100–125°C for 1–12 hr). Amino acid composition, tannins, phytic acid and trypsin inhibitor activity were determined. Almost all essential amino acids declined after cooking. Less than 10% of total tannins were decomposed during cooking, while up to 50% were leached to the cooking liquor. Retention of phytic acid in cooked beans was significantly lower than in cooked bean-liquor mixtures. Loss of phytic acid due to leaching was much higher for easy-to-cook beans than for hard-to-cook ones. Apparent retention of trypsin inhibitor activity amounted to about 50%. Optimum heat treatments were 125°C at 1 hr for easy and 120°C at 2 hr for hard-to-cook beans.     

Effects of Vacuum Hydration on the Incidence of Splits in Canned Kidney Beans (Phaseolus vulgaris)

Dry red kidney beans were canned using two different pretreatments: soaking for 12 hr at 20°C, and vacuum hydration for 5 min followed by soaking for 2 hr at temperatures from 45-59.1°C. Samples were then packed, processed to commercial sterility, and tested for percentage of split beans after processing. Vacuum hydration pretreatments greatly decreased the incidence and severity of splitting in the canned product and accelerated water uptake while retaining the same moisture content after soaking as the conventional soak treatment. Vacuum-hydrated beans gained less moisture during retorting than conventionally treated samples.     

Histamine Production in Soy Extended Tuna Salads

Histamine production in tuna salads extended with textured soy protein (TSP) was evaluated. Salads were inoculated with five known histamine-producing bacteria and held at 8°C, 24°C, and 37°C for up to 48 hr. Addition of 30% TSP to tuna salads resulted in higher initial pH and favorable growth conditions for microorganisms and histidine decarboxylase activity. Addition of 15% TSP provided an initial pH for maximal enzyme and histamine production but somewhat slower microbial growth. Tuna salad extended with either 15% or 30% TSP developed toxic levels of histamine (>50 mg/l00 g) when held at either 24° or 37°C for 6 hr. Nonextended tuna salads did not develop toxic levels of histamine even when inoculated with known histamine-producing bacteria and held at 24° or 37°C for 48 hr.     

Roasting of Navy Beans (Phaseolus vulgaris) by Particle-to-Particle Heat Transfer

A rotating chamber dry roaster using pre-heated ceramic beads as heat transfer media was used to roast navy beans. Processing conditions were: beads temperature, 240 and 270°C; bean-to-bead ratio, 1/10 and 1/15 and contact times of 1 and 2 min. Product temperatures achieved ranged from 92–125°C for the eight runs. Heat transfer coefficients varied from 3.6–23.4 W/(m²) (°C). Roasted products showed reduced water-soluble nitrogen content and gel forming capacity, increased water-holding capacity and cold paste viscosities, and no changes in available lysine and degree of starch damage. Residual trypsin inhibitor (TIA) and hemagglutinin activity varied from 92 to 22%, and 48 to 1%, respectively. A correlation was found to exist between nitrogen solubility index and TIA of products. Roasting caused fracture and separation of hulls, and facilitated their removal.     

HEAT TREATMENT AND INACTIVATION OF TRYPSIN-CHYMOTRYPSIN INHIBITORS AND LECTINS FROM BEANS (Phaseolus vulgaris L.)

This work investigates some factors affecting the inactivation of common bean trypsin inhibitor and phytohemagglutin. Trypsin inhibitor activity was totally stable to heat treatment (30 min, 97C) in the total protein extract, albumin or globulin fraction. Heat treatment of the whole beans easily inactivated the inhibitor. Heat resistance of trypsin inhibitor was intermediate in the bean flour which received the same heat treatment. Independent of sample, the inhibitor was very stable to heat treatment at neutral and acidic pH and labile under strong alkaline conditions. Heating for 30 min in boiling water at pH 12 resulted in complete inactivation of the trypsin inhibitor. Autoclaving (121C) soaked whole beans and flour for 5 min inactivated 55% of the trypsin inhibitor activity in the soaked flour and 75% in the whole beans. After autoclaving 20 min, inactivation of trypsin inhibitor was about 65% in the flour and 80% in the whole beans. The phytohemagglutinin (lectin) activity was totally destroyed in the autoclaved beans after 5 min and in the flour after 15 min.     

Canning Quality Evaluation of Pinto and Navy Beans

Thermal processing of pinto and navy beans at 121.1°C for 16 or 14 min in a still retort gave similar sterilization value (F_o= 10) as the processing at 115.6°C for 45 min. The 121.1°C/16 or 14 min process produced beans with greater firmness than the 115.6°C/45 min process. The addition of CaCl₂ and EDTA improved firmness and color of canned beans. Calcium chloride also reduced clumping and splitting of the canned beans. Sensory evaluation showed that the acceptability of canned beans was reduced when CaCl₂ was increased up to 10 mM. High correlation between firmness and soluble pectin in various bean cultivars implied that soluble pectin content could be used as a parameter for screening bean cultivars with desirable firmness.     

Phytate Reduction in Brown Beans (Phaseolus vulgaris L.)

Brown beans (Phaseolus vulgaris L.) were subjected to treatments to evaluate effects of pH, temperature, CaCl₂, tannase and fermentation on degradation of phytate. Soaking was performed at 21°C, 37°C and 55°C at pH 4.0, 6.0, 6.4, 7.0, and 8.0. Optimal conditions for phytate degradation were pH 7.0 and 55°C. After soaking 4, 8 or 17 hr at these conditions 79%, 87% and 98% of phytate was degraded, respectively. Addition of tannase enhanced reduction of phytate. Fermentation of presoaked whole beans resulted in reduction of 88% of phytate after 48 hr.     

Effects of Time Postmortem of Electrical Stimulation and Postmortem Chilling Method on Pork Quality and Palatability Traits

Twenty market hogs were used in this study to determine the effects of electrical stimulation (ES) administered at various times postmortem (5, 15-20, or 30-40 min) and chilling treatment (Conventional = 24 hr at 0-2°C, or Rapid = 34°C for 3 hr then 0-2°C for 21 hr) on pork quality and palatability traits. The findings of this study indicated that ES of hog carcasses, particularly at 5 or 15-20 min postmortem, detrimentally affects quality by inducing a paler color, reducing muscle firmness, and increasing muscle separation. Rapid chilling lessened these detrimental effects. Cooking loss, cooking time. shear force values, and palatability traits were not affected by ES or chilling rate.     

Effect of Centrifugation on Hemagglutinin Activity Assessment in Common Beans

The effect of centrifugation in the determination of hemagglutinin (lectin) activity was assessed. Seeds of two bean cultivars (Phaseolus vulgaris) were used for this study. The saline extracts of lectins from soaked and/or cooked samples showed significant decreases in hemagglutinin activity after centrifugation, whereas the activity of the same extracts from raw beans (control) did not change after this separation step. These results suggest that the use of centrifugation affects the hemagglutinin activity assessment.     

Assessment of Previous Heat Treatment of Laboratory Heat-Processed Meat and Poultry using a Commercial Enzyme System

The APIZYM enzyme system was assessed with respect to: enzyme activity in aqueous and saline extract filtrates from raw and heat processed (60° and 71.1°C) beef; effect of rate of heating (0.2–0.3°C, 0.4–0.5°C, and 0.9–1.0°C/min) to internal temperatures of 66.7°, 67.8°, 68.9°, 70.0°, and 71.1°C and holding times of 0, 15, 30, 45, and 60 min at these temperatures on residual enzyme activity; reduction of enzyme assay incubation time; and reproducibility of the system. Results showed that slightly higher enzyme activity in heated samples was obtained with 0.9% saline extraction compared to water. Greater enzyme activity was observed in filtrates from pork samples heat-processed at a fast rate than at a slow rate. Enzyme activity could be detected after 2 hr incubation, but 4 hr were needed for the enzymes to react with their respective substrates. The system was found to be reproducibile. The results of this study also indicated the potential of using leucine aminopeptidase as an indicator enzyme for determining the adequacy of heat treatment of meat and poultry products.     

α-Amylase inhibitor levels in seeds generally available in Europe

The α-amylase inhibitor (αAI) levels in 18 seeds, which are generally available throughout Europe, have been determined. Kidney beans, haricot beans, pinto beans and runner beans had high contents of αAI (2–4 g equivalent kg^?1 seed meal). Butter beans, blackeyed peas, chickpeas, field beans and sweet lupinseeds contained 0.1–0.2 g inhibitor equivalent kg^?1 seed meal. No αAI activity was detected in samples of adzuki bean, lentils, mung beans, peas, soya beans, sunflower seeds or winged beans. The αAI activity present in whole kidney beans was relatively heat-resistant. However, it could be completely abolished by aqueous heat treatment of fully imbibed beans at 100°C for 5–10 min.     

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.     

Effect of Thermal Processing on the Survival of Foot-and-Mouth Disease Virus in Ground Meat

Foot-and-mouth disease virus was examined for its stability during cooking in tissues from infected cattle. The 0₁ (CANEFA 2) serotype of foot-and-mouth disease virus survived in lymph node tissues after heating for 2 hr at 69°C, for 1 hr but not for 2 hr at 82°C, and for 15 min but not for 0.5 hr at 90°C. Incorporation of 1% NaCl into suspensions of infected lymph nodes enhanced viral survival after heating for 0.5 hr but not for 1 hr at 90°C. The virus did not survive in either ground beef or meatballs contaminated with infected lymph node tissue, when processed to internal temperatures of 93.3, 96.1 or 98.8°C using commercial thermal processing procedures. Accurate temperature measurements were achieved with a temperature sensitive indicator disc developed in this study.     

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.     

Purification and Characterization of a Lectin from the Seeds of Amaranth (Amaranthus cruentus)

A lectin (ACL) was purified from the seeds of Amaranthus cruentus using affinity chromatography on fetuin-agarose. Apparent homogeneity of the lectin was demonstrated by SDS-PAGE, chromatography on Sephadex G100 and immunoprecipitation. The lectin was a dimer with an estimated molecular weight of 66,000 and a subunit molecular weight of 35,000. ACL-mediated agglutination was inhibited by D-GalNAc and fetuin. Thirty other carbohydrates were non-hibitory. ACL contained 2.2% neutral carbohydrate and relatively high levels of aspartic acid, glutamic acid, serine and glycine. The purified lectin was relatively heat labile retaining approximately 10% of its original activity (titer) after 5 min at 70°C and after just 1 min at 100°C.