Abstract This study was designed to investigate changes in quality characteristics during long-term storage of five commercial grape vinegars (V1~V5). To determine long-term quality characteristics of vinegars, proximate (soluble solid, pH, total acidity, color, and antioxidant activity) and sensory descriptive analysis, were performed. Initial soluble solids were high in V4 and V5 (contained higher liquid fructose or grape concentrate), but after 12 mo of storage, soluble solids decreased significantly in V4 and V5 (non-sterile products). Initial total acidity was close to the amount of additional juice, while V4 and V5 had increased total acidity after 12-mo storage. Browning was dominant in V4 and V5 regardless of storage periods. Initial DPPH radical scavenging activity was high for all samples, while it tended to decrease after 6-mo storage. In sensory descriptive analysis, browning and turbidity was markedly elevated during 12-mo storage in general. Aromatic factors were significantly attenuated in all test samples during storage. Interestingly, V4 and V5 were considered as having lower sourness and bitterness since sweetness was stronger in these than in other samples due to the addition of liquid fructose. The results suggest that for optimal quality, commercial grape vinegars are best consumed within 6 mo of storage after opening.

Abstract This study aimed to investigate the rheological properties of rice milk produced from raw rice including rice varieties and milling fractions. Rice milk was prepared from two rice varieties, which were Arhent (long grain) and Bengal (medium grain) using brown, head and broken fractions of the two cultivars used. Gelatinization temperatures for each rice variety, milling fraction, and rheological behaviors of rice milk were examined. Flow behaviors of rice milk were significantly affected by the variety and milling fractions of raw rice. The different amylose to amylopectin ratios of the two varieties, the compositional differences and the subsequent impact on the gelatinization temperature of raw rice used in rice milk were the primary reasons for these differences. Rice milk prepared from Bengal showed greater consistency coefficients, showing a Newtonian flow behavior compared to the rice milk made from Arhent variety. Broken rice showed a potential to be as a raw material in the rice milk industry since it showed similar flow properties compared to the head rice (i.e. within the same variety).

Abstract The objective of the present study was to investigate the rheological, pasting, and thermal properties of octenyl succinic anhydrate (OSA)-modified potato starch. Potato starch was modified using different concentrations of OSA (0, 1, 3, and 5%, v/v). The degree of substitution (DS) for the OSA-modified starch ranged from 0.0012 to 0.0055. The amylose leaching values of native and OSA-modified potato starch with different DS levels were in the range of 47.09-87.32%. The gel strength values of the OSA-modified starch were lower than those of native potato starch. Rapid Visco Analyzer data showed that peak, hot pasting, final and setback viscosities of the native starch decreased after OSA modification. Dynamic shear rheological tests, conducted at 4 °C, indicated that OSA-modified potato starch had weak gel-like behavior with the storage moduli (G') higher than the loss moduli (G”) over most of the frequency ranges (0.63-63.8 rad·s-1).