PERCEIVED TEXTURAL DIMENSIONS OF FRUIT-BASED BEVERAGES

The major sensory dimensions of the mouthfeel of fruit based beverages were determined by principal components analysis and the degree of correlation between mouthfeel characteristics and the taste and pleasantness of beverages was assessed. Untrained college students rated 35 different beverages on 16 different 10-point scales containing mouthfeel, taste and hedonic terms. Two major mouthfeel dimensions emerged with this set of beverages and they were termed density/thickness and chemical irritant effect. An interdependence between mouthfeel and taste ratings was also found. Sweetness ratings were negatively correlated and sour, salty and bitter tastes were positively correlated with mouthfeel terms describing oral mucosal irritation.     

Identification of Key Textural Attributes of Fluid and Semi-Solid Foods Using Regression Analysis

Regression analysis was used to identify key attributes from 15 textural terms generated by a panel for 27 fluid and semi-solid commercial foods. A search using single independent variables showed that “thick” gave the best average R² with a value of 0.548; a search with two independent variables showed that “thick” and “soft” gave the best average R² of 0.748; a search with three attributes showed that “slippery”, “thick,” and “soft” gave the highest R² values of 0.803. The final equations provided a set of regression parameters which can be used to predict twelve textural attributes from scores obtained for “thick”, “soft”, and “slippery”.     

Video camera calibration for optical densitometry

An efficient technique for calibrating video cameras to record optical density (OD) from microscopic images is described. The method corrects for variation over the field of the brightfield and darkfield intensities, does not assume a linear response of the camera to the incident intensity and requires a single calibration filter.     

Practical significance of relative assimilable nitrogen requirements of yeast: a preliminary study of fermentation performance and liberation of H2S

Saccharomyces cerevisiae wine yeast strains AWRI 796 and AWRI 835, representing a high and a low nitrogen-requiring strain respectively, were cultured in media of varying nitrogen (ammonium) content. Ammonium utilisation, biomass yield, fermentation progress and the liberation of hydrogen sulfide were monitored. Findings from this study support the original classification of these strains in terms of their relative requirement for nitrogen. Accordingly, when compared with AWRI 835 grown under the same conditions, the high nitrogen-requiring strain, AWRI 796, removed c. 8% more nitrogen from the medium, produced c. 7 to 13% more biomass, failed to complete fermentation in the time frame of the experiment and liberated hydrogen sulfide in greater amounts and/or over longer periods. These findings confirm that measures of relative nitrogen requirement form an extremely useful parameter by which to select strains that are better suited to the problem-free fermentation of musts of low nitrogen content.