Effects of Microwave Heating and Gamma Irradiation on Phytate and Phospholipid Contents of Soybean (Glycine max. L.)

The effect of microwave heating and gamma irradiation treatments on phosphorus compounds of soybean seeds were studied. Inorganic phosphorus was significantly (P < 0.05) increased while, phytate and phospholipids were significantly decreased when soybean seeds were microwave-heated for 9 min or more. Furthermore, gamma-irradiation treatments of 20 KGy or more significantly increased inorganic phosphorus and decreased phytate and phospholipids of the beans. Two dimensional thin-layer chromatography was employed to study the phospholipid pattern. Gamma-irradiation at doses from 40 to 100 KGy produced lysophosphatidylcholine and phosphatidic acid. The data of this study showed that, the increase of inorganic phosphorus was mainly due to the decomposition of phytic acids and phosphates of inositol.     

Property Characterization of Peanut Kernels Subjected to Gamma Irradiation and Its Effect on the Outgrowth and Aflatoxin Production by Aspergillus parasiticus

Peanut kernels inoculated with Aspergillus parasiticus conidia and uninoculated kernels were gamma irradiated with 0 to 15 kGy using ⁶⁰Co. Levels of 2.5 and 5.0 KGy were effective in retarding the outgrowth of A. parasiticus and reducing the population of natural mold contaminants. However, elimination of these molds was not achieved. When irradiated with doses higher than 10 KGy, seed germinations were inhibited, changes in proteins were observed and oil stabilities decreased. After 4 wk incubation of the inoculated kernels in a humidified condition, aflatoxins produced by surviving A. parasiticus ranged from 69.12 to 13.48 μg/g depending upon the original irradiation dose.     

Biochemical characterization of esterase from soybean (<Emphasis Type="Italic">Glycine max</Emphasis> L.)

Esterases are enzymes that present good potential in industrial application, and soybean seed can represent an alternative source for this enzyme. The extraction and esterase activity of Brazilian soybean seeds (Glycine max L.) were evaluated. Esterase activity was found in both the germinated and non-germinated seeds at 2.90 and 1.70 U/mg, respectively, with a concentration in the powdered extract (freeze dried) of 100 mg/mL. The enzyme showed a preference for the hydrolysis of short chain fatty acids (120.02 U/mL) and optimum pH for activity was pH 8.0 with optimum temperatures of 40 and 80°C. The enzyme showed stability at 70°C showing 60% of residual activity and activity increased with the addition of the following salts: NaNO₃, K₂SO₄, and Na₂SO₄ in the reaction medium.     

Application of electron paramagnetic resonance (EPR) spectroscopy for control of irradiated food

Four groups of foodstuffs were irradiated in a ⁶⁰Co source with doses from 0.3 to 10kGy and subsequently measured by EPR spectrometry at room temperature in air: (1) poultry bones and fins, scales and bones of carp. (2) seeds of selected fruits, (3) dehydrated mushrooms, and (4) a selected set of spices and herbs. Qualitative and, in some cases, quantitative data related to the absorbed dose of radiation were collected. In the irradiated bones from poultry and carp an asymmetric singlet (g_I = 2.0030, g_II =1.9973; ΔH_pp = 0.85 mT) was detected which was stable at room temperature and was similar to that previously found in irradiated mammalian bones. Another stable EPR signal (g₀ = 2.0024, ΔH_pp = 0.56 mT) was found in the fins and scales of carp which was about five times more intense in fins than in scales. In pips of pears irradiated with a dose of 3 kGy. a signal which was about twice as intense as the endogenous signal was recorded. A multicomponent EPR signal derived from the stones of dates differed from the endogenous signal even when a low dose (0-5 kGy) was applied. A multicomponent EPR signal is also observed in dried mushrooms irradiated with a dose of 3 kGy. In white mustard, paprika and chilli no native EPR signal exists and a radiation-induced stable EPR signal can still be observed after a period of 3 months. The radiation-induced EPR signal in black pepper was highly sensitive to moisture and disappeared, yet the native signal survived. The pilot experiments performed with irradiated stones of cherries, plums, lemons, apple pips, raspberries, cranberries, red currants, blackcurrants, gooseberries and tomatoes showed the induction of short-lived EPR signals of no practical use for the control of food irradiation.     

Detection of Vibrio vulnificus Before and After γ-irradiation in Quahog Clam (Mercenaria mercenaria) Tissue Using Real-Time Polymerase Chain Reaction

The effects of γ?–irradiation on the destruction of Vibrio vulnificus in quahog clam tissue (Mercenaria mercenaria) by real-time PCR (Rti-PCR) were studied. The Rti-PCR methodology used in this study employed four sets of V. vulnificus specific primers, which were utilized to amplify 1000, 700, 300, and 70-bp sequences of the vvhA to determine the percent detection of V. vulnificus genomic targets after γ?–irradiation. Tissue homogenates seeded with V. vulnificus were irradiated to gradually reduce the viable CFU by accumulating dosage. The use of these four pairs of primers to amplify DNA target sequences of varying length in seeded tissue exposed to 1.4 KGy failed to discriminate between irradiated and nonirradiated cells. In contrast, with doses of 2.0, 3.0, and 5.0 KGy, the amplification of 700, 300, and 70-bp sequences resulted in higher Ct values, respectively, and lower levels of amplification with each primer pair, reflecting increased DNA fracture with increasing dose. When varying numbers of CFU in tissue homogenates (1.0 × 10³ to 1.0 × 10⁶ per gram of tissue) were exposed to 3.0 KGy of γ-irradiation, DNA amplicons of 1000 and 700-bp derived from 1 × 10⁵ CFU/g and below failed to be detected in contrast to 300 and 70-bp amplicons, which were detected with CFU levels of 1.0 × 10⁵/g. This study showed that with increasing dose, the larger amplicons (100 and 700-bp) failed to be detected, which corresponded to zero percent survival of CFU.     

Effect of gamma irradiation of phosphine-fumigated dates on the development of Ephestia cautella (Walker) (Lepidoptera: Pyralidae)

Possible toxicological effects from interactions between gamma radiation (1 KGy at 46 rad/s) and phosphine residues in fumigated dates were studied when the dates were fed to Ephestia cautella. The results showed comparable development, fecundity and fertility of this insect when reared on a complete diet of fumigated, irradiated, fumigated irradiated or untreated dates.     

Disinfestation of stored wheat grain and flour using gamma rays and microwave heating

Samples of wheat grain and flour (20 gm of each) were infested with 20 larvae or 5 pairs of adult insects of Tribolium confusum, Lasioderma serricorne, Corcyra cephalonica or Rhyzopertha dominica. The infested samples were tested as follows : (1) microwave heating at four temperature levels 40, 45,50 and 55 °C, for exposure times from10 to 50 s; (2) gamma irradiation over the dose range of 0.5-4 KGy; (3) gamma irradiation + microwave heating. Complete kill of all stages tested was achieved at 50 °C with an exposure time of 50 s. A dose of 2 KGy induced 100% mortality of R. dominica after three days, but it took up to 7 days for all T. confusum and L. serricorne adults to die after a 4-KGy exposure. All insects died within 24 h when exposed to the combination of 1KGy + 50 °C for 30 s.Biochemical analyses on the samples of wheat grain and flour subjected to those treatments at which high mortality was obtained generally showed no detectable changes in the quality of protein, fat, fiber, carbohydrates or ash. The germination of wheat grain was lowered after treatment with microwave radiation but was not affected by a dose of 1 KGy gamma radiation.     

Jatropha platyphylla, a new non-toxic Jatropha species: Physical properties and chemical constituents including toxic and antinutritional factors of seeds

Local communities in Mexico consume Jatropha platyphylla seeds after roasting. The kernels of J. platyphylla contained ca. 60% oil and were free of phorbol esters. The kernel meal of this Jatropha species contained trypsin inhibitor, lectins and phytate. However, trypsin inhibitor and lectins are heat labile so this explains why the local people can eat roasted seeds without ill effects. Heat-treated J. platyphylla kernel meal (JPKM) was free of trypsin inhibitor and lectin activities. Crude protein content of JPKM was 75%. Heated JPKM and soybean meal were included in a standard diet (crude protein 36%) for Nile tilapia (Oreochromis niloticus) to replace 50% of the fish meal protein. The growth of fish in all the three groups was statistically similar and the blood biochemical parameters that serve as biomarkers for toxicity were within the normal ranges. This is the first study that confirms the non-toxic nature of J. platyphylla.     

Inactivation of trypsin inhibitor,lectin and urease in soybean by hydrothermal treatment

The effects of hydrothermal treating parameters on trypsin inhibitor (TI), lectin and urease activities in whole soybean seeds were investigated by Response Surface Analysis (RSA). Independent variables with equidistant levels examined in this study were the following: treating temperature (levels: 70, 85 and 100°C), treating time (levels: 10, 30 and 50 min), and soaking time (2, 4 and 6 h). The functions between treating parameters and responses values of TI, lectin and urease activities in treated soybean were calculated by multiple, non-linear regression analysis and analysis of variance. Mathematical models were developed in this study to predict TI, lectin and urease activities in soybean during hydrothermal processing and they have been found to be significant (P[%] = 0.1, 1.0, and 0.1, respectively). Differences between the effects of processing parameters on the inactivation of TI, lectin and urease in soybean were observed and they can be seen either from the mathematical models or the typical figures. The modeling of the effects should help in selection of optimal parameters of hydrothermal treatment for destruction of TI. lectin and urease in soybean. Based on the modeling, lectin and urease can be fully inactivated in soybean treated at proper conditions, while remaining TI activity can be expected in soybean treated at any conditions examined in this study.     

Effects of roasting,powdering and storing irradiated soybeans on hydrocarbon detection for identifying post-irradiation of soybeans

Hydrocarbons, which are produced by irradiation of lipid-containing foods, were analyzed in irradiated soybeans, which were roasted, powdered and stored, to determine whether these treatments affect hydrocarbon detection for identifying post-irradiation of soybeans. Soybeans were irradiated (Irr), irradiated and roasted (Irr–Rst), roasted and irradiated (Rst–Irr), irradiated, roasted and powdered (Irr–Rst–Pwd), and roasted, powdered and irradiated (Rst–Pwd–Irr). They were stored at refrigerated or room temperature for 30 weeks. Oils were extracted using hexane and Na₂SO₄. Hydrocarbon fraction was separated through a Florisil column and analyzed using GC. Hydrocarbons 17:2, 16:3, 17:1 and 16:2 were not detected in non-irradiated soybeans and soybean powder, but they were detected in those irradiated at 0.5 kGy or higher. The levels of the hydrocarbons increased with dose. The hydrocarbon levels in the Irr–Rst, Rst–Irr, and Irr–Rst–Pwd soybeans were little different from those in the Irr soybeans. Hydrocarbon detection in the Rst–Pwd–Irr soybean powder showed a slightly different pattern from those in the other treatments. Hydrocarbon levels in the soybean and soybean powder samples stored at refrigerated temperature for 30 weeks changed little, compared to initial samples. The hydrocarbon detection patterns in the samples stored at room temperature for 30 weeks were similar to the initial and refrigerated samples with slightly lower detection levels in the room-stored samples.     

Effect of Some Potentially Synergistic Treatments in Combination with 100 Krad Irradiation on the Iced Shelf Life of Cod Fillets

Irradiation of cod fillets with a maximum absorbed dose of 100 Krad extended iced storage life by about 9 days. Further extension of several days resulted when irradiation was combined concurrently with either 60% CO₂ packaging atmosphere or sorbate additive. Packaging at low oxygen tension did not provide any additional benefit for irradiated fish. No important difference in storage life of treated fish was observed due to one vs three day postmortem age. The 100 Krad treatment extended grade B quality market life as opposed to grade A (prime quality) market life. Certain physical/chemical tests were evaluated for their efficacy in estimating spoilage. Concentrations of TMA, DMA, hypoxanthine, APC and pH at spoilage were comparable in control and air-irradiated samples, but were less in sorbate-irradiated fillets.     

Inhibitory effects of legume seed extracts on fish proteinases

Proteinase inhibitor extracts were prepared from various legume seeds. Black cowpea and soybean seeds showed the highest inhibitory activity against viscera proteinases (p < 0.05). Optimal extraction was attained by shaking the defatted legume seed powder in distilled water (3 ml g⁻¹) at ambient temperature for 1 h. Both extracts showed high thermal stability, but that from soybean was slightly less stable. The inhibitory activity of both extracts was retained over a broad pH range. The proteinase inhibitor extracts also reduced modori-inducing proteinase (MIP) activity. The sarcoplasmic MIP activities were more effectively inhibited than the myofibrillar-associated MIP activities. © 1999 Society of Chemical Industry     

Effect of gamma irradiation on physicochemical properties,proximate composition,vitamins and antinutritional factors of the tribal pulse Vigna unguiculata subsp. unguiculata

Effect of gamma irradiation on Vigna unguiculata subsp. unguiculata seeds (maroon‐coloured seed coat) at various doses (2, 5, 10, 15 and 25 kGy) on the physicochemical properties, proximate composition, vitamins (niacin and ascorbic acid) and antinutritional factors were analysed. No significant changes were recorded in the physicochemical properties of irradiated seeds. Gamma irradiation resulted in a significant increase in crude protein, while the crude lipid, crude fibre and ash contents resulted in a dose‐dependent decrease. Gamma‐irradiated seeds presented a significant decrease in the ascorbic acid and niacin content. Irradiation processing significantly reduced the level of L‐DOPA, phytic acid, hydrogen cyanide, trypsin inhibitor activity, oligosaccharides and lectins. The total free phenolics, tannins and in vitro protein digestibility on irradiation showed a significant dose‐dependent increase. Gamma irradiation seems to be a good procedure to improve the quality of legume seeds from the nutritional point of view.     

Effect of fungal damage by Fusarium spp and Diaporthe/Phomopsis complex on protein quantity and quality of soybean seed

Seeds from three soybean genotypes were tested to evaluate the effect of fungal damage by Fusarium spp and Diaporthe/Phomopsis complex on protein quantity and quality. Fungus‐infected seeds had higher protein contents than uninfected ones. A selective degradation of soluble proteins was detected in seeds infected with either fungus. Some of the storage proteins degraded were identified as α′, α and β subfractions of the β‐conglycinin, and A₃ subfraction of the glycinin. Furthermore, reductions in lipoxygenase and trypsin inhibitor activities were observed in fungus‐infected seeds. Amino acid composition did not vary between infected and uninfected seed lots, so protein degradation should not affect amino acid structures. Copyright © 2004 Society of Chemical Industry     

Gamma irradiation as a means to eliminate Listeria monocytogenes from frozen chicken meat

Cells of Listeria monocytogenes ATCC 35152 were sensitive to gamma irradiation in phosphate buffer, pH 7.00 (D₁₀, dose required for 10% survival—0.15 kGy) at 0–5°C. The cells showed higher radiation survival when irradiated under frozen condition, with a D₁₀ of 0.3 kGy. The protection offered by shrimp/chicken/kheema homogenates (100 g litre^?1) was evidenced by even higher D₁₀ values (0.5 kGy) at both 0–5°C and cryogenic temperature. Boneless chicken meat samples were artificially inoculated with L monocytogenes ATCC 35152 cells at low (5 × 10³) colony-forming unit (cfu) g^?1 and high (5 × 10⁶ cfu g^?1) concentrations and irradiated at 1, 3, 4, 6 kGy doses under cryogenic conditions. The efficacy of the radiation process was evaluated by detecting L monocytogenes during storage at 2–4°C in the irradiated samples. These studies, when repeated with three other serotypes of L monocytogenes, clearly suggested the need for a dose of 3 kGy for elimination of 10³ cfu cells of L monocytogenes g^?1 from air-packed frozen chicken meat.     

COMPARATIVE STUDIES ON PROTEOLYTIC ACTIVITY OF SPLENIC EXTRACT FROM THREE TUNA SPECIES COMMONLY USED IN THAILAND

Proteolytic activities of splenic extract from three tuna species including skipjack tuna (Katsuwonus pelamis), yellowfin tuna (Thunnus albacores) and tongol tuna (Thunnus tonggol) were studied. Optimal activity of splenic extract from all tuna species was at pH 9.0 and 55C when casein was used as a substrate. Among all species tested, yellowfin tuna showed the highest activity, followed by skipjack tuna and tongol tuna. The proteolytic activity was strongly inhibited by soybean trypsin inhibitor, TLCK and partially inhibited by ethylenediaminetetraacetic acid. E‐64, N‐ethylmaleimide, iodoacetic acid, TPCK and pepstatin A showed no inhibition. The effect of NaCl and CaCl₂ on proteolytic activity was also investigated. Activities continuously decreased as NaCl concentration increased, and no activity remained in the presence of 30% NaCl. On the other hand, activities increased as CaCl₂ concentration increased. The highest activity was obtained in the presence of 1 mM CaCl₂. SDS‐substrate gel electrophoresis revealed that major proteinases in splenic extract from different tuna species were different in apparent molecular weights and sensitivity to TLCK. Although the major activity bands of all species were strongly inhibited by soybean trypsin inhibitor, varying sensitivity to TLCK probably implied the differences in binding characteristic of enzyme to substrate and/or inhibitors. The results suggest that major proteinases in spleen of all tuna species were trypsin‐like serine proteinases.     

Preparation and Evaluation of Supercritical Carbon Dioxide Defatted Soybean Flakes

Full-fat soybean flakes were extracted with supercritical carbon dioxide (SC-CO₂) at pressures of 10,600–12,400 psi, temperatures from 80–100°C, and moisture levels of 5–13.5%. Conditions could be selected to produce defatted soybean meals with nitrogen solubility indices greater than 70% and flavor scores greater than 6.5 on a scale of 1 to 10 (1 = strong and 10 = bland). The usual grassy-beany and bitter flavors of hexane-defatted soybean flours were only minimally detectable in the optimally SC-CO₂-extracted materials. Bland, defatted soybean meal prepared by SC-CO₂ extraction was further processed into high-quality protein concentrates and isolates that were stable when stored under adverse conditions.     

Chemical composition and nutritional attributes of selected newly developed lines of soybean (Glycine max (L) Merr)

The chemical composition and nutritional properties of raw, autoclaved and boiled samples of three promising advanced breeding lines of soybean (TG_x 923 ? 2^EN, TG_x 1019 ? 2^EN and TG_x 1497 ? 1^D), part of a larger collection evaluated in agronomic field trials in Nigeria, were investigated. Protein quality was evaluated using weanling albino rats fed diets which were formulated to supply 10% protein using soybean samples, with casein as a control. Raw seeds contained 35.6–42.4% crude protein, 8.9–9.8 mg iron per 100 g, 8.62–18.21 mg trypsin inhibitor g^?1 and 2.25–6.15 mg phytic acid g^?1 seed flour. TG_x 923 ? 2^EN possessed higher crude protein contents and lower amounts of trypsin inhibitor, polyphenol and phytic acid compared with TG_x 1019 ? 2^EN or TG_x 1497 ? 1^D. Boiling proved more effective than autoclaving for reducing the levels of antinutrients and improving the protein quality of the beans, as shown by the higher values for weight gain, protein efficiency ratio (PER), net protein ratio (NPR) and true digestibility (TD) of boiled samples. There were no significant (p > 0.05) differences between the values obtained for PER, NPR and TD of diets containing boiled samples of TG_x 923 ? 2^EN and casein, indicating the nutritional superiority of this soybean line compared with TG_x 1019 ? 2^EN and TG_x 1497 ? 1^D. © 2002 Society of Chemical Industry     

LOW DOSE IRRADIATION of 'RAINIER'SWEET CHERRIES AS A QUARANTINE TREATMENT

'Rainier'cherries, with and without gibberellic acid treatment were subjected to radiation at dose levels of 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, and 1.0 KGy and held for 14 and 21 days at 1C before removal from storage and quality determined. No variation in fruit or stem color, soluble solids, titratable acidity or sensory difference was noted at any of the radiation dose levels. There was 13% loss in firmness due to radiatlon treatment between 0.4 and 1.0 KGy. Cherries that were treated with gibberellic acid were superior candidates for radiation treatment. 'Rainier'cherries can be irradiated as soon as quality parameters have reached acceptable levels for commercial harvest.     

PURIFICATION AND CHARACTERIZATION OF BACILLUS SUBTILIS JM-3 PROTEASE FROM ANCHOVY SAUCE

Bacillus subtilis JM‐3 was isolated from anchovy sauce naturally fermented in an underground cellar at 15 ± 3C for 3 years. The activity of the B. subtilis protease was highest in the 40–60% ammonium sulfate fraction. The yield of the purified protease was 5.3%, and its purification ratio was 35.6 folds. The molecular weight of the B. subtilis protease was 17.1 kDa, and its K_m and V_maxvalues were 1.75 μg/mL and 318 μM 1/min, respectively. The optimal temperature for protease activity was 60C, but optimal stability temperature was 30C. The optimal pH for protease activity and stability was 5.5. Therefore, the B. subtilis JM‐3 protease was classified as an acid protease. The relative activities of the B. subtilis JM‐3 protease were 69, 21 and 1.3% at 10, 20 and 30% NaCl concentrations, respectively. The best substrate for the B. subtilis JM‐3 protease was benzyloxycarbonyl‐glycine‐p‐nitrophenyl ester followed by bovine serum albumin. p‐Toluene‐sulfonyl‐L‐lysine chloromethylketone was the strongest inhibitor followed by soybean trypsin inhibitor, but N‐ethylmaleimide did not inhibit this enzyme. The B. subtilis JM‐3 protease was therefore presumed to be a trypsin‐like serine protease.