Optimization of processing methods for deodorizing Periplaneta americana based on subjective and objective smell evaluation combined with analysis of volatile components / 中草药

Objective: To screen a processing method suitable for deodorizing of Periplaneta americana (PA) through subjective and objective evaluation combined with changes in volatile components, and explore the mechanism of deodorization. Methods: Raw, vinegar-processed, wine-processed, wheat bran-processed products of PA were prepared respectively. Volunteer sensory evaluation combined with electronic nose system was used to evaluate the odor difference between raw and processed products to screen a better processed product. HS-SPME-GC-MS and ROAV were used to analyze the key odorous components of PA. The peak area normalization method combined with multivariate statistical analysis were used to analyze the difference of volatile components between raw and processed products to explore the mechanism of processing. Results|| Volunteer scores showed that the average scores of raw, vinegar-processed, wine-processed, wheat bran-processed products were 3.38, 1.25, 2.88, and 3.04, respectively. The results of the electronic nose showed that the Euclidean distance between the raw and vinegar-processed, wine-processed, wheat bran-processed products were 7.34, 3.77 and 1.60, respectively, but the direction of scatter of vinegar-processed product was opposite to that of wine-processed product and wheat bran-processed product, suggesting that the mechanism of deodorization may be different. Vinegar processing was determined as the optimum method for deodorizing by comprehensive analysis of subjective and objective evaluation data. The key odor components of PA were 3-methyl butanal, hexanal, nonyl aldehyde, heptaldehyde, decyl aldehyde, phenyl acetaldehyde, (E,E)-2,4-nonadienal, 2-pentylfuran, (+)-limonene, and myristic aldehyde. The PCA result of volatile components showed that four kinds of processed products can be clearly distinguished, and there were differences in volatile components and content. There were seven differential chemical components between raw and vinegar-processed products, including hexanal, palmitic acid, oleic acid, acetic acid, ethyl oleate, ethyl palmitate, and ethyl linoleate. The content of vinegar-processed products was lower than that of raw products, especially the key odorous component hexanal. Conclusion: The vinegar processing is a better method to improve the odor of PA, and its mechanism may be associated with reducing odorous components such as hexanal.

Efeito da radiação gama sobre a oxidação lipídica da carne bovina / Effect of gamma radiation on lipid oxidation of beef

Objetivou-se avaliar o efeito de diferentes doses de radiação (1, 2, 3, 6 e 9 kGy) sobre a oxidação lipídica de contrafilés bovinos pela determinação das substâncias reativas ao ácido 2-tiobarbitúrico (TBARS) e por cromatografia gasosa utilizando a técnica de microextração em fase sólida (SPME). As amostras irradiadas apresentaram maior concentração de aldeídos, com maior incidência de nonanal, independentemente da dose aplicada. Maiores concentrações de hexanal foram observadas nas amostras irradiadas por maiores doses (6 e 9 kGy), mas os maiores valores de TBARS foram observados nas amostras irradiadas por 3 e 6 kGy. Uma redução nos valores de aldeídos, especialmente nonanal e octanal, foi observada para amostras irradiadas por 2 kGy quando comparadas às demais amostras irradiadas. Conclui-se que o processo de irradiação aumentou o grau de oxidação das amostras, que consequentemente, aumentou a concentração dos aldeídos presentes.

Optimization of Malaxation Process using Major Aroma Compounds in Virgin Olive Oil

ABSTRACT Optimization of major aroma compounds in olive oils produced from fruits at three maturity stages wasstudied. A central composite design was used for the optimization of malaxation conditions of temperature and times, each at five levels with 13 runs including five central points. The responses of interest were trans-2-hexenal and hexanal, which were investigated and their contents were optimized. A full quadratic second order regression model including the linear, quadratic, and two factor interaction effects was proposed to explain the variation in the contents of target compounds depending on the malaxation conditions. Adequacies of models were evaluated by checking regression coefficients for each model. Models were found to work with high success for trans-2-hexenal prediction for oils from fruits at both purple and black stages, whereas the model for hexanalwas only in black stage oil. Their regression coefficients were higher than 0.86. Influences of time and temperature for the malaxation process were found to be significant for the transition of major aroma compounds from the fruit matrix to olive oil. The optimum conditions of temperature and time pairs to maximize trans-2-hexenal and hexanal was found to be 23°C/31 minutes for black olive and to maximize only trans-2-hexenal was also 29°C/41 minutes for purple olive.

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.