Automatic monitoring method of apple browning for determining optimal inhibitor mixtures.
Apple browning is an undesirable biochemical change that decreases the value of apple produces on the food market. The colour of apples starts changing immediately after being cut, the speed of colour-change depending on apple-variety and environment: sweeter apples become brown quicker, warmer environment favorizes the browning speed. Monitoring apple browning is part of food quality control and part of studying ways to decrease the browning speed by using different types of inhibitors (anti-browning agents). The monitoring is usually done with colorimetric devices such as spectrophotometers and colorimeters. We propose an alternative way of monitoring colour changes during the browning process for optimizing inhibitor mixtures for fresh-cut green apples, using the Trichromatic Colour Analyser (TCA) system, which turns scanner into colorimeter. TCA has been initially created for the complete study of the traditional Thai colours and subsequently developed for other tasks, one of them being the automated monitoring of fruit browning. One of the main advantages of TCA over other colour measurement devices is the capability of obtaining colorimetric values over a flexible port-size with a maximum aperture of 100 x 100 mm. In our research we mixed different quantities of ascorbic acid (10 g/L), citric acid (10 g/L) and sodium chloride (10 g/L) using proportions specified by simplex centroid pattern, in order to obtain an optimized inhibitor for browning process of Granny Smith green apple types. The automated TCA monitoring process was compared with the automated monitoring using a Konica Minolta CR400 colorimeter for 28.3 hours with a 1300 seconds time-interval between measurements. The optimized inhibitor mixture depended on time frame (initial time, t0 and time t).