Abstract:
Food attributes, e.g. appearance, quality and nutritional value are the main factors that consumers are concerned with when choosing food products. Since quality is becoming more important, its control requires that objective, rapid, non-destructive and quantitative methods be developed and used to measure it. New Zealand dairy products contribute significantly to both a domestic and an export trade. Products such as cream, whipped cream and ice cream change their shape and surface characteristics, sometimes rapidly, based on internal and external factors. The quantification of these changes would allow a better understanding of the effect of these factors on product quality. The main goal of this research was to develop and apply practical tools for quantifying cream visual attributes. Color and appearance (L*a*b*, CCI and color difference), shininess, view area and shape variation were investigated by using machine vision system, and laser line analysis assisted by developed software. A battery of tests under three different temperatures (room temperature, 10oC and 2oC) were conducted and new methods of analysis were developed. It was found that color primitives (CCI) and color difference (E) should be used in quantifying the non-uniformity of color. Average L*a*b* may give an idea about color. Using a line laser and image analysis, four methods were developed to quantify the shape variation of cream: height analysis for cream samples, length of the laser line, area under rotated and shifted curve, and area under the turn angle vs normalized length curve. The first three methods could quantitatively analyze shape changes. Analysis results showed that significant changes happened in the early period of storage. Therefore, more value information should be obtained during this period. Correlation of these methods with sensory evaluation of cream will result in rapid, repeatable, quantitative, and non-destructive methods of evaluating cream.
