Soybean Homogenates Research Articles

Combined diet of yeast, fermented soybean meal, and microparticulate as larval feed in extensive rearing systems for seed production of the oriental river prawn Macrobrachium nipponense

The present study aims to evaluate the effects of several types of larval feed on seed production of the oriental river prawn Macrobrachium nipponense and water quality in extensive rearing systems. Healthy M. nipponense were distributed into fifteen 15-m2 pond outdoors, and each pond was stocked with 90 prawns including 41 egg-bearing (berried) female prawns, 37 not bearing female prawns, and 12 male prawns for larval production. The experimental design was completely randomized, with four diet groups (diet A: soybean homogenate, diet B: yeast, diet C: yeast + fermented soybean meal, and diet D: yeast + fermented soybean meal + microparticulate diet) and one no feeding control and three replications. There are equal levels of the total protein content in diets A–D. Higher larvae and postlarvae number was obtained for diet C and diet D. Furthermore, the increase of M. nipponense larvae and postlarvae in diets B–D can result in the decrease of zooplankton and increase of phytoplankton in the pond during some periods, simultaneously improving the water quality. The Spearman correlation coefficient (rM,N) between the amounts of larvae and postlarvae of M. nipponense per pond and zooplankton per pond during the entire experiment period was − 0.56. The highest juvenile M. nipponense production was obtained in the diet D group (3140.00 ± 461.63), which was slightly higher than that in the diet C group (2940.33 ± 382.60). The juvenile M. nipponense production in diet B (2303.00 ± 449.23) was also significantly higher compared to diet A (1106.33 ± 176.64) and the control group (1039.67 ± 212.85). There were no significant differences in the amounts of juvenile M. nipponense between the control and diet A groups, which indicated that the soybean homogenate could not increase the amount of M. nipponense juveniles. Our results clearly showed that diet D significantly raised per unit yield of prawn seed comparing with no feeding and other diet group in extensive rearing systems and that the cost of producing prawn seed with diet D is low, which provide an important foundation for the expansion of oriental river prawn culture.

Reduction of Off‐Flavor Generation in Soybean Homogenates: A Mathematical Model

The generation of off-flavors in soybean homogenates such as n-hexanal via the lipoxygenase (LOX) pathway can be a problem in the processed food industry. Previous studies have examined the effect of using soybean varieties missing one or more of the 3 LOX isozymes on n-hexanal generation. A dynamic mathematical model of the soybean LOX pathway using ordinary differential equations was constructed using parameters estimated from existing data with the aim of predicting how n-hexanal generation could be reduced. Time-course simulations of LOX-null beans were run and compared with experimental results. Model L2, L3, and L12 beans were within the range relative to the wild type found experimentally, with L13 and L23 beans close to the experimental range. Model L1 beans produced much more n-hexanal relative to the wild type than those in experiments. Sensitivity analysis indicates that reducing the estimated Km parameter for LOX isozyme 3 (L-3) would improve the fit between model predictions and experimental results found in the literature. The model also predicts that increasing L-3 or reducing L-2 levels within beans may reduce n-hexanal generation.Practical Application: This work describes the use of mathematics to attempt to quantify the enzyme-catalyzed conversions of compounds in soybean homogenates into undesirable flavors, primarily from the compound n-hexanal. The effect of different soybean genotypes and enzyme kinetic constants was also studied, leading to recommendations on which combinations might minimize off-flavor levels and what further work might be carried out to substantiate these conclusions.

Effect of Soybean Volatile Compounds on Aspergillus flavus Growth and Aflatoxin Production

Soybean homogenates produced volatile compounds upon exposure to lipase. These induced volatiles were identified by SPME. Seventeen volatile compounds identified by SPME were chosen for determination of their ability to inhibit Aspergillus flavus growth and aflatoxin B(1) (AFB1) production in a solid media assay. These volatiles included aldehydes, alcohols, ketones, and furans. Of the tested compounds, the aldehydes showed the greatest inhibition of fungal growth and AFB1 production. These compounds inhibited up to 100% of the observed growth and AFB1 production as compared to the controls. The greatest activity by the aldehydes to disrupt growth was ranked as follows: 2,4 hexadienal > benzaldehyde > 2-octenal > (E)-2-heptenal > octanal > (E)-2-hexenal > nonanal > hexanal. The greatest activity by the aldehydes to reduce AFB1 was ranked as follows: (E)-2-hexenal > 2,4 hexadienal > (E)-2-heptenal > hexanal > nonanal. (E)-2-hexenal and (E)-2-heptenal were tested further in an A. flavus-inoculated corn kernel assay. Both compounds prevented colonization by A. flavus and eliminated AFB1 production when exposed to compound volumes < 10 muL as also shown in the solid media assay. The results suggest that soybeans react to lipase by production of potent antifungal volatiles.

Oxylipin Metabolism in Soybean Seeds Containing Different Sets of Lipoxygenase Isozymes after Homogenization

The oxylipin metabolism was analyzed in soybean homogenates containing different sets of lipoxygenase isozymes (L-1, -2, and -3); namely, Suzuyutaka (containing L-1, -2, and -3), Yumeyutaka (containing only L-1), Kanto102 (containing L-2), Kyushu119 (containing L-3), and Ichihime (lacking all three isozymes). The amount of oxidized fatty acids in the esterified form was higher than that in the free form with every cultivar. Kanto102 formed the highest amount of oxidized lipids, and Yumeyutaka and Ichihime formed the lowest. With Kanto102 and Kyushu119, high amounts of keto fatty acids were formed, while they were undetectable with Yumeyutaka and Ichihime. Due to the lack of lipoxygenases in Ichihime, an accumulation of free fatty acids was expected; however, their amount in Yumeyutaka was significantly lower than was expected. It is suggested that a pathway existed to form C6-volatiles through hydroperoxides in the esterified form.

Effect of Soybean Lipoxygenase on Volatile Generation and Inhibition of Aspergillus flavus Mycelial Growth

Volatiles generated from lipoxygenase (LOX) normal and LOX deficient soybean (Glycine max) varieties with and without added lipase inhibited Aspergillus flavus mycelial growth and aflatoxin production. Soybean volatiles were analyzed using a solid phase microextraction (SPME) method combined with gas chromatography-mass spectrometry (GC-MS). Twenty-one compounds, including 11 aldehydes, three alcohols, four ketones, one furan, one alkane, and one alkene were detected in the LOX normal soybean line. However, only nine volatile compounds were observed in the LOX deficient soybean variety. The antifungal aldehydes hexanal and (E)-2-hexenal were observed in both LOX normal and LOX deficient lines and were detected at significantly higher amounts in soybean homogenate with added lipase. These aldehydes may be formed through alternate pathways, other than the LOX pathway, and may account for the inhibition of A. flavus growth observed. Other volatiles detected, particularly the ketones and alcohols, may contribute to the antifungal activity observed in both LOX normal and LOX deficient soybean lines. These results suggest that other factors, other than LOX activity, may better explain why soybeans are generally not as severely affected by A. flavus and aflatoxin contamination as other oilseed crops.

Allergenicity test of genetically modified soybean in Sprague Dawley rats.

Allergenicity of genetically-modified (GM) soybean was evaluated in male Sprague Dawley rats. To confirm the GM soybean used in this study, the polymerase chain reaction (PCR) was performed using the chromosomal DNA of soybeans. The PCR result provided the clear discrimination of genetically-modified (GM) soybeans. To evaluate the allergenicity of GM soybean and non-GM control one, the soybean homogenate was sensitized subcutaneously 3 times a week for 3 weeks. The doses of soybean were 0, 2 and 20 mg/kg in the protein basis. A week after the last sensitization, antisera were recovered from individual animals. When the sera were injected intradermally on the clipped back of unsensitized rats with various dilutions, followed by a challenge with 20 mg/kg of soybean homogenate containing 1% Evans blue, no sign of passive cutaneous anaphylaxis reaction was detected. In addition, when the sera were treated in the cultures of peritoneal mast cells, the increase of histamine release by anti-(GM soybean) sera was not observed when compared to that by anti-(non-GM soybean) sera. The present results indicate that the GM soybean might not act as a strong allergen in male Sprague Dawley rats.

Degradation of Vitamin E, Vitamin C, and Lutein in Soybean Homogenate: A Comparison of Normal Soybean and Lipoxygenase- Lacking (Triple-Null) Soybean

The degradation of antioxidative compounds such as vitamin E, vitamin C, and lutein in aqueous homogenate prepared from normal soybean seeds (L123) or lipoxygenase-lacking soybean seeds (triple-null mutant, L0) was investigated. In the normal soybean, these natural antioxidants decreased rapidly after homogenization. On the contrary, in the L0 soybean, vitamin E was hardly degraded, and vitamin C and lutein were slowly degraded in comparison with normal soybean. The radical [1,1-diphenyl-2-picrylhydrazyl (DPPH)] scavenging activity of each soybean was determined using an ESR spectrometer, and it was shown that the scavenging activity of normal soybean was weakened after homogenization with water, whereas this reduction was not observed in L0 soybean. These results suggested that lipoxygenase-lacking soybean could become a superior food ingredient which improves not only the flavor of soybean products but also its nutritional quality and functionality. Keywords: Soybean; lipoxygenase; vitamin E; radical sc...

Enzymic Pathway to Ethyl Vinyl Ketone and 2-Pentenal in Soybean Preparations

Previous work by this laboratory showed that under anaerobic conditions and the presence of a polyunsaturated fatty acid, soybean (Glycine max L.) lipoxygenase isoenzymes converted a lipoxygenase-catalyzed oxidation product of linolenic acid, 13(S)-hydroperoxy-9(Z),11(E),15(Z)-octadecatrienoic acid, into 1-penten-3-ol, 2(Z)-penten-1-ol, and 13-oxo-9(Z),11(E)-tridecadienoic acid. It seemed plausible that the “raw bean odor”, ethyl vinyl ketone, previously isolated from soybean homogenates by other workers could arise from oxidation of 1-penten-3-ol by alcohol dehydrogenase. It is shown here that both ethyl vinyl ketone and 2-pentenal are produced by a soybean preparation after anaerobic incubation with 13(S)-hydroperoxy-9(Z),11(E),15(Z)-octadecatrienoic acid and linolenic acid and that NAD+ stimulated the formation of 2-pentenal. In the presence of NAD+, two separable isoenzymes of soybean alcohol dehydrogenase were capable of utilizing as substrates both 1-penten-3-ol and 2(Z)-penten-1-ol, as well as (2E)-hexen-1-ol. In terms of substrate preference indicated by Km, the order was 2(E)-hexen-1-ol > 2(Z)-penten-1-ol > 1-penten-3-ol. Because ethyl vinyl ketone formed in the presence of only 13(S)-hydroperoxy-9(Z),11(E),15(Z)-octadecatrienoic acid and linolenic acid in the absence of NAD+, another pathway also seemed possible. Keywords: Lipoxygenase; 1-penten-3-ol; 2(Z)-penten-1-ol; alcohol dehydrogenase; ethyl vinyl ketone; 2-pentenal; linolenic acid; hydroperoxide; flavor

Soybean Flour Lipoxygenase lsozyme Mutant Effects on Bread Dough Volatiles

ABSTRACTLipoxygenases are implicated in improvement of bread quality after addition of enzyme active soy flour. However, differences among the three major isozymes in soybeans in terms of impact on bread characteristics are not known. Differences exist among soybean lipoxygenase isozymes in terms of stability and generation of volatile flavor and aroma. Soybean flour with different lipoxygenase isozymes present might affect bread dough volatiles or defatting may affect activity of the isozymes. Full fat or defatted soy flour could be added to bread dough. Defatting selectively reduced lipoxygenase 2 activity with little effect on lipoxygenases 1 and 3. Addition of full fat soy flour from mutant isolines indicated that as with soybean homogenates, lipoxygenase 2 is mostly responsible for undesirable aroma compounds. Much higher levels of volatile alcohols were found in soy flour amended bread dough than in soy flour homogenates alone.

Evidence Implicating the Lipoxygenase Pathway in Providing Resistance to Soybeans AgainstAspergillus flavus

The fungus, Aspergillus flavus, secretes lipases while parasitizing oilseed hosts and may contaminate the seed with aflatoxin. We found that exogenous lipase applied to soybean cotyledons results in the generation of volatile aldehydes by the lipoxygenase pathway that halts the growth of fungi. Volatiles generated from untreated homogenized soybeans did not affect the germination of A. flavus spores in a closed petri plate assay in which spores were streaked on corn-meal agar and soybean homogenate was placed on the lid of the inverted plate. When lipase (500 units/ml) was added to the soybean homogenate, all fungal spore germination was inhibited [...]

大豆リポキシゲナーゼに関する研究 （第４報） 大豆ホモジネート中のリポキシゲナーゼ活性に対する各種阻害剤の効果

大豆リポキシゲナーゼに関する研究 （第４報） 大豆ホモジネート中のリポキシゲナーゼ活性に対する各種阻害剤の効果

N‐Hexanol Formation from n‐Hexanal by Enzyme Action in Soybean Extracts

ABSTRACTn‐Hexanal in soybean homogenates decreased during incubation at alkaline pH. When soybean extracts were dialyzed and then incubated with n‐hexanal and cofactors [nicotinamide adenine dinucleotide (NAD+), the reduced form (NADH), nicotinamide adenine dinucleotide phosphate (NADP+), and the reduced form (NADPH)], NADH and NADPH stimulated the enzymatic reduction of n‐hexanal with NADH being more effective than NADPH. When undialyzed preparations were incubated, all the cofactors stimulated enzymatic activity, with NADH being the most effective. The reaction product in all the incubation mixtures was n‐hexanol; n‐hexanal was reduced to n‐hexanol stoichiometrically. It was suggested that alcohol dehydrogenase was responsible for the decrease of n‐hexanal in soybean homogenate at alkaline pH.

Lipoxygenase-2 isozyme is responsible for generation of n-hexanal in soybean homogenate

Lipoxygenase-2 isozyme is responsible for generation of n-hexanal in soybean homogenate