Josemeyre Bonifácio da Silva

Chemical and physical composition of grain-type and food-type soybean for food processing

Abstract – The objective of this work was to evaluate the chemical and physical characteristics of grains of soybean ( Glycine max ) cultivars for food processing. The soybean cultivars evaluated were: grain-type – BRS 133 and BRS 258; food-type – BRS 213 (null lipoxygenases), BRS 267 (vegetable-type) and BRS 216 (small grain size). BRS 267 and BRS 216 cultivars showed higher protein content, indicating that they could promote superior nutritional value. BRS 213 cultivar showed the lowest lipoxygenase activity, and BRS 267, the lowest hexanal content. These characteristics can improve soyfood flavor. After cooking, BRS267 cultivar grains presented a higher content of aglycones (more biologically active form of isoflavones) and oleic acid, which makes it proper for functional foods and with better stability for processing, and also showed high content of fructose, glutamic acid and alanine, compounds related to the soybean mild flavor. Because of its large grain size, BRS 267 is suitable for tofu and edamame, while small-grain-sized BRS 216 is good for natto and for soybean sprouts production. BRS 216 and BRS 213 cultivars presented shorter cooking time, which may be effective for reducing processing costs.Index terms:

Changes in the isoflavone profile and in the chemical composition of tempeh during processing and refrigeration

The objective of this work was to analyze changes in the isoflavone profile, determined by high performance liquid chromatography, at different processing stages and after refrigeration of tempeh. For tempeh production, clean soybean grains from cultivars BR 36 (low isoflavone content) and IAS 5 (high) were dehulled, and the separated cotyledons were hydrated and then cooked in boiling water for 30 min. Spores of the fungus Rhizopus microsporus var. oligosporus were inoculated in the cooked and cooled cotyledons, and incubated at 32oC for 6, 12, 18, and 24 hours in perforated polypropylene bags, for fermentation. The resulting tempeh was stored at 4oC for 6, 12, 18, and 24 hours. After 24‑hour fermentation, isoflavone glucosides were 50% reduced, and the aglycone forms in the tempeh from both cultivars was increased. The malonyl forms reduced 83% after cooking. Less than 24 hours of refrigeration did not affect the isoflavone profile of tempeh from either cultivar, which is a good indicator of its quality. The tempeh maintains the high and low isoflavone content of the cultivars, which indicates that cultivar differences in this trait should be considered when processing tempeh.

Relationships among sensory analysis, isoflavone and hexanal contents of soymilk powder

The objective of this work was to study the sensory attributes and their relationships with isoflavones and hexanal contents of soymilks made in laboratory and commercial samples. The laboratory soymilk samples showed cooked grain and cotton candy aroma and cooked grain, malty and sweetness flavor (a mild flavor). The commercial samples presented stronger roasted soy, rancid, sesame seeds and fishy aroma and roasted soy, sesame seeds and bitterness flavor, and bitter taste (closed nose) and starchy texture. No differences were noted among laboratory soymilks, denoting inactivation of lipoxygenases enzymes in the soymilks process. There were differences between the samples prepared in laboratory and commercial soymilks, which was due to several factors related to processing techniques. The hexanal average content was positively associated with the cooked grain aroma and isoflavones was positively associated with the cooked grain and cotton candy aroma, cooked grain, malty and sweetness flavor and starchy texture.

Evaluation of the shelf-life of vegetable-type soybean pods

The shelf-life of the vegetable-type soybean pods stored under different conditions was evaluated by chemical characteristics and color. The pods were harvested in the R6 stage and stored either at 30 or 7oC for 9 d. After the storage period, the pods were blanched and threshed, and the immature green grains were used for the analysis. The protein content decreased after 6 d of storage at 7oC. There was no difference in the lipid content after the storage at 30 and 7oC for 9 d. The starch and sucrose contents decreased after the first day of storage at 30oC. There was no difference in trypsin inhibitor activity until 6 d of storage at 30 and 7oC. The green color of the pods that was an indication of the quality that was maintained when stored at 7oC during 3 d. To preserve the quality of vegetable-type soybean, pods should be stored at 30oC and consumed within 24 h or stored at 7oC for up to 3 d of storage.

Effects of storage time and temperature on the characteristics of vegetable-type soybean grain minimally processed

The objective of this study was to evaluate the effects of storage time and temperature on the characteristics of vegetable-type soybean grain (cultivar BRS 267) minimally processed and to define the best conditions for its storage. The evaluation was performed by measurement of vitamin C levels, weight loss and color parameters (L*, a*, and b*). The time of storage of vegetable-type soybean grains minimally processed and storage in Styrofoam trays and wrapped with PVC film, caused a decreased in vitamin C levels and color parameters and increased weight loss. This process was intensified with higher temperature at 25 °C than 5°C. To maintain appropriate levels of vitamin C, weight and color of vegetable-type soybean grains minimally processed and storage in trays wrapped in plastic wrap, recommended storage for 3 days at 5°C.

Soybean β-Glucosidase immobilisated on chitosan beads and its application in soy drink increase the aglycones

The objective of this study was to investigate the immobilisation efficiency of soybean β-glucosidase (181.6 U/mL; 23.8 mg protein/mL) on activated chitosan beads. Central Composite Rotational Design (CCDR) 23 was used and the application of immobilised enzyme in commercial soy drink was evaluated. The activation of chitosan beads was achieved with established 2.5% glutaraldehyde, pH 7.5, 8 h incubation time (6 h with agitation and 2 h without agitation) at 37oC. The highest immobilisation efficiency (%) of soybean β-glucosidase on chitosan beads obtained was 37.74 U/mL and 18.84 mg protein/4 chitosan beads at pH 7.5 and 20 h coupling time of enzyme-matrix (7 h with agitation and 13 h without agitation) at 4oC. The immobilised enzyme incubated at 50oC, pH 5.5 resulted in 24% increase in the aglycones content in commercial soy drink after 60 min.

Postharvest quality, antioxidant activity and acceptability of strawberries grown in conventional and organic systems

The aim of this study was to evaluate the influence of organic and conventional cultivation systems and the cultivars on the postharvest quality, antioxidant activity and acceptability of strawberries. Strawberries of the cultivars Albion, Monterey and San Andreas were analysed with respect to the soluble solids content (SS), titratable acidity (TA), SS/TA ratio, fruit colour, vitamin C content, antioxidant activity by the DDPH method, mineral composition and acceptability. The cultivation systems and cultivars had different influences on the SS, TA, pH, SS/TA and colour of the strawberries. The vitamin C content of cv. Monterey was higher (78.68 mg ascorbic acid 100 g-1) than that of cv. San Andreas (70.28 mg ascorbic acid 100 g-1) in the conventional system, while in the organic system, the cultivars did not differ. Differences were not observed amongst the cultivars and cultivation conditions for antioxidant activity and the cultivation systems and cultivars had no effect on the P, Cu and Mg mineral contents. The conventionally cultivated strawberries of cv. Monterey obtained the highest value for acceptance (7.51) while the organically cultivated strawberries of cv. San Andreas received the lowest value (6.58).