Technological characteristics of tofu from soybean coagulated with cardoon flower extract.

The objective of the present study was to develop tofu with soybean-water soluble extract coagulated with cardoon flower (F1) and magnesium chloride (MgCl2, F2). The produced tofu was characterized in terms of physical, chemical, microbiological, and sensory properties during 14 days of storage. The yield of F1 was higher (p < 0.05) (195 g/100 soybean seeds) than F2 (162 g/100 soybean seeds). F1 presented higher moisture, protein, acidity, syneresis, and lipids when compared with F2, and a reduction of these contents during the storage. F1 presented lower hardness, stickiness, springiness, and cohesiveness compared with F2. The acceptability of F1 showed a score of 6.00 and F2 of 4.68, and the purchase intention was 3.22 for F1 and 2.23 for F2. This study recommended the use of cardoon flower at 35% level as it has great potential as a coagulant for the elaboration of tofu with higher yield, and acceptability and reasonable purchasing intention.

Evaluation of packaging systems with O2-absorbers on quality of minimally processed soybean sprouts.

This study evaluated the influence of O2-absorbing sachets into different packages polyethylene terephthalate (PET - E1), low density polyethylene (LDPE - E2), and PET/LDPE (E3) on the quality of minimally processed soybean sprouts (MP-sprouts). The MP-sprouts were stored up to 12 days and characterized for physicochemical, microbiological and sensory attributes. The O2-absorbing sachet showed changes during exposure to the environment by the formation of amorphous iron hydroxide, which was observed by the analysis of functional groups and XRD. The packaging used in the study showed high transmittance and clarity, and low Haze, being a good feature for storing the MP product. All packaging systems showed an increase in the volume of absorbed oxygen (cm3) up to 9 days of storage. The physic-chemical characteristics of the MP-sprouts stored for 12 days were preserved in the different packages, showing no difference regarding the use of the O2-absorbing sachet. The O2-absorbing sachet not influenced the quality of MP-sprouts during the stored (12 days). The best visual aspect was observed in PET package (with and without O2-absorbing sachet) being classified as excellent, without color change. The MP-sprouts also fulfilled the microbiological quality standards and presented 75.11% acceptability and 72.40% purchase intention.

Electronic tongue system to evaluate flavor of soybean (Glycine Max (L.) Merrill) genotypes

An electronic tongue system was tested as a fast and efficient analytical tool for flavor evaluation of soybean genotypes. Grain samples of 25 soybean lines were analyzed using 0.25 g of milled samples added to 100 mL of distilled water and mixing for one minute on a magnetic stirrer. An aliquot (50 mL) from the filtered liquid was used for the analysis on a pre-fixed frequency of 1 kHz and alternate tension of 50 mV. Two analyses were conducted in a complete randomized design with three replicates. Electrical response (capacitance) of eight polymeric chemical sensors used to analyze the soybean lines were submitted to Principal Component Analysis (PCA). In the spatial distribution of the PCA graphic, the lines close to each other were similar, while the distant ones showed different characteristics. The electronic tongue system was efficient in discriminating flavor of soybean lines.

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.

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.

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.

O trabalho foi conduzido com o objetivo de descrever os atributos sensoriais de bebidas de extratos de soja em pó produzidos a partir de cultivares desprovida de lipoxigenases, convencional e tipo hortaliça e dois extratos comerciais e correlacioná-los com as quantidades de isoflavonas e n-hexanal nos extratos em pó. Os extratos de soja em pó obtidos em laboratório foram caracterizados pelos atributos: aroma de feijão cozido e de algodão doce; sabor de grão cozido, de malte e gosto doce sugerindo, sabor suave. Os extratos comerciais apresentaram forte aroma de soja tostada, de ranço, de sementes de gergelim e de peixe; sabor de soja tostada, gosto amargo e de sementes de gergelim; gosto amargo (com nariz preso) e consistência de amido. Não foram observadas diferenças sensoriais entre os extratos produzidos em laboratório, indicando a ocorrência da inativação das enzimas lipoxigenases durante o processamento dos produtos. Contudo, diferenças marcantes entre os extratos obtidos em laboratório e os comerciais quanto aos atributos sensoriais estudados foram encontradas provavelmente, devido às técnicas desconhecidas de processamento utilizadas pelos fabricantes dos produtos comerciais. O teor médio de n-hexanal presente nos extratos de soja comerciais e produzidos em laboratório apresentou correlação positiva e significativa com o atributo aroma de grão cozido, já a quantidade de isoflavonas com aroma de grão cozido e de algodão doce, sabor de grão cozido, de malte, gosto doce e consistência de amido.