Physical alterations of soybean during accelerated and natural aging

Quantitative Trait Locus Mapping of Seed Vigor in Soybean under -20 °C Storage and Accelerated Aging Conditions via RAD Sequencing

Due to its fast deterioration, soybean (Glycine max L.) has an inherently poor seed vigor. Vigor loss occurring during storage is one of the main obstacles to soybean production in the tropics. To analyze the genetic background of seed vigor, soybean seeds of a recombinant inbred line (RIL) population derived from the cross between Zhonghuang24 (ZH24, low vigor cultivar) and Huaxia3hao (HX3, vigorous cultivar) were utilized to identify the quantitative trait loci (QTLs) underlying the seed vigor under -20 °C conservation and accelerated aging conditions. According to the linkage analysis, multiple seed vigor-related QTLs were identified under both -20 °C and accelerated aging storage. Two major QTLs and eight QTL hotspots localized on chromosomes 3, 6, 9, 11, 15, 16, 17, and 19 were detected that were associated with seed vigor across two storage conditions. The indicators of seed vigor did not correlate well between the two aging treatments, and no common QTLs were detected in RIL populations stored in two conditions. These results indicated that deterioration under accelerated aging conditions was not reflective of natural aging at -20 °C. Additionally, we suggest 15 promising candidate genes that could possibly determine the seed vigor in soybeans, which would help explore the mechanisms responsible for maintaining high seed vigor.

Impact of soybean aging conditions on tofu sensory characteristics and acceptance

BACKGROUND

Tofu from aged soybeans is of poor quality, mainly with respect to texture. Texture defects described in the literature are contradictory. No study has investigated all sensory properties simultaneously. The objective of the present study was to evaluate the effect of soybean aging conditions [natural: ambient temperature and RH, 18 months, and accelerated: 30 °C, 84% relative humidity (RH), 6 months] on all of the sensory characteristics and the acceptance of tofu. Texture and color were also evaluated via an instrumental method. The control condition was -20 °C and 47% RH. Coodetec 214 and BRS 267 cultivars were studied.

RESULTS

The effect of soybean accelerated aging on tofu sensory characteristics and acceptance was more pronounced compared to the natural condition. The two cultivars had a similar behavior. Tofu control exhibited a light, uniform and bright color, cohesive appearance, sweet aroma and flavor, as well as a firm and elastic texture. Tofu made from both aged cultivars showed a gray color with dark spots, a rough appearance, fermented aroma, rancid flavor, an astringent and bitter taste, a fracturable texture and adherence to the oral cavity after chewing. These characteristics of tofu from aged soybeans implied a low acceptance by consumers.

CONCLUSION

Tofu from natural and accelerated aged soybeans has sensory attributes of appearance, as well as aroma, flavor and damaged texture, that are unacceptable by consumers. © 2017 Society of Chemical Industry.

Effect of soybean aging on the quality of soymilk, firmness of tofu and optimum coagulant concentration

This study investigated the influence of soybean aging (cultivars Coodetec 214 and BRS 267) on the physicochemical properties of soymilk and tofu. Two aging conditions were adopted: accelerated aging (84% relative humidity and 30 °C, up to 9 months) and natural aging (ambient temperature and relative humidity, up to 18 months) and a control condition (47% relative humidity, -20 °C). Tofu was coagulated with MgSO4. Optimum coagulant concentration (OCC) decreased with increasing coagulation temperature and soybean aging time. OCC showed positive correlation with total solids, protein, ash, Ca, Mg and P contents of soymilk. The products showed, in general, reduced color parameters (L(∗) and h°), proteins, lipids, carbohydrates, ash, Ca, Mg, P and total solids (except in the tofu) and firmness (tofu) with increasing aging time. Tofu yields decreased with accelerated aging time.