Rapid and simple quantification methods have been developed to enumerate viable bacterial cells from food materials. Those developed technologies can be used for self-inspection of food products and food processing lines by food companies. In this review, the author summarizes the rapid quantification technologies for viable bacterial counts using kinetic analysis. These technologies can estimate the number of viable bacterial cells by measuring indicator micro-organisms and there is a high correlation between detection time and viable bacterial cell number. These methods enable the evaluation of microbiological risk in food materials and provide high-throughput results. These methods could be a useful tool for the rapid evaluation of microbial food contamination and prediction of microbial growth in actual food materials.

The effects of water jet treatment on dispersion and gelation of deacylated potassium gellan gum in the presence of calcium were investigated. In the presence of calcium, gellan gum was finely dispersed in water, “Fine dispersion with Ca^2＋”, by the water jet treatment at 245 MPa (the temperature of the solution reached 90 °C), or just dispersed without the water jet treatment, “Just dispersion with Ca^2＋”, and then heated to 90 °C. Thereafter, both gellan gum dispersions were cooled to 10 °C. “Fine dispersion with Ca^2＋” formed gel by cooling, but “Just dispersion with Ca^2＋” did not form gel only by heating and cooling. Conventionally, gellan gum is just dispersed in water and heated to 90°Cin the absence of calcium, and then calcium is added followed by cooling to obtain gel formed using “Just dispersion before Ca^2＋ addition”. The gelation behavior of gel formed using “Just dispersion before Ca^2＋ addition” was compared with that of gel formed using “Fine dispersion with Ca^2＋”. Circular dichroism spectroscopy and dynamic mechanical analysis revealed that the coil-helix transition temperature and sol-gel transition temperature were not significantly different between gels formed using the two methods. The storage modulus value at 10°Cof “Fine dispersion with Ca^2＋” gel was lower than that of “Just dispersion before Ca^2＋ addition” gel. In agreement with this result, compression testing revealed the low breaking stress of gel formed using “Fine dispersion with Ca^2＋”. Furthermore, scanning electron microscopy demonstrated that the microstructure of gel formed using “Fine dispersion with Ca^2＋” was coarse compared to that of gel formed using “Just dispersion before Ca^2＋ addition”.

Low-carbohydrate diets have anti-obesity effects induced by decreases in insulin secretion. Since insulin promotes the synthesis of proteins, the possibility that low-carbohydrate diets will decrease skeletal muscle weight is of concern. The purpose of this study was to examine whether low-carbohydrate, high-fat diets decrease skeletal muscle weight in mice. Ten-week-old male ICR mice were assigned to three groups (n＝8 each) according to the energy proportion of carbohydrates in their diets as follows: Carb64 (protein:fat:carbohydrate＝20:16:64), Carb32 (20:48:32), and Carb16 (20:64:16). The mice were dissected after four weeks. Low-carbohydrate, high-fat diets may decrease skeletal muscle weight by decreasing Myog expression, while the diets increased body weight.

The characteristic aroma of roasted Arabica coffee and its potent odorants were investigated using sensory evaluation and Aroma Extract Dilution Analysis (AEDA) in comparison to Robusta coffee. Sensory evaluation of the Arabica ground coffee beans revealed the aroma characteristics to be sour, floral, and fruity notes. AEDA and gas chromatography-mass spectrometry analysis of the volatile fractions of the ground coffee beans, prepared by the dynamic headspace technique, revealed that 3-mercapto-3-methylbutyl formate (MMBF) is the specific potent odorant of Arabica coffee. However, the odor quality of MMBF (catty) was not consistent with the characteristics of Arabica coffee aroma (sour, floral, fruity). Therefore, the cause of this inconsistency was investigated using sensory evaluation, and it was suggested that the interaction between MMBF and the other odorants in the coffee is closely related to the formation of the unique aroma of Arabica coffee. In addition, the Arabica coffee contained a larger quantity of compounds relating to the formation of MMBF compared to the Robusta coffee, which suggested that the formation of Arabica coffee’s unique aroma is closely correlated with the contents of MMBF precursors in the coffee beans.