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Abstract: Non-invasive, sensor-based technologies are increasingly considered as preferred methods for evaluating quality attributes of agricultural products. This study investigated the feasibility of a laser light backscattering analysis at three wavelengths (532, 650, 780 nm) for predicting moisture content (MC), shrinkage (S), lightness (L*), chroma (C*) and hue (h*) changes of papaya during drying. Convective hot air drying was conducted at four temperatures (50, 60, 70, 80 °C), during which time the product was sampled and subjected to non-destructive optical analysis as well as reference measurements. From laser images, the illuminated area (A I ) and light intensity (I L ) were used to assess the backscattering profiles that represent photon migration in the fruit tissue. As expected, drying temperatures significantly affected the quality attributes of dehydrated papayas. Increasing drying temperature resulted in a decrease in MC, L*, and C* values, whereas h* and S values were increased. The results also revealed that each backscattering factor obtained can potentially be used to describe each quality change, except for C* value. In addition, multivariate correlations of measured A I and I L parameters at 650 nm wavelength were found to precisely yield the best fit for MC, L*, and h* predictions (R 2 > 0.92). Therefore, the study concludes that the use of laser backscattering methods provides a useful tool for quality control as a rapid, consistent, non-intrusive and objective method for in-line measurement of product quality in fruit drying processes. [Copyright &y& Elsevier]

This study explored the effects of calcium chloride ( Ca Cl2) and calcium lactate ( Ca- L) pretreatments prior to osmotic dehydration on physicochemical characteristics and consumer acceptance of dried papaya. Three different calcium concentrations [0.5, 1.5 and 2.5% (w/v)] were applied to samples before they were soaked in a 30 °Brix sucrose solution and subsequently dried at 70 °C. The results showed that the dried samples treated with calcium exhibited significantly lower moisture content, water activity, apparent density and shrinkage, while volume was higher when compared to the control. Calcium applications did not obviously influence sugar content of samples and maintained the quality of dried papaya in terms of colour and textural characteristics. Calcium chloride at 2.5% (w/v) was found to particularly impart undesirable bitterness to the dried papaya. In contrast, using 2.5% (w/v) Ca- L provided the best acceptance scores. Thus, the use of Ca- L could be an alternative to Ca Cl2 in the pretreatment of fruits prior to drying as it offers improved quality. [ABSTRACT FROM AUTHOR]