A study on limiting heat treatment induced quality defects in watermelon juice

Watermelon juice is not consumed and produced in large quantities due to their undesirable odor that occurs after heat treatment. Therefore, in order to limit the odor defects that occur during processing, optimum heat treatment conditions were determined for watermelon juice and the changes in some quality properties depending on the heat treatment conditions were mathematically modeled. The effects of resin applications (R1, R2, R3), antioxidant additions (gallic acid-G and coumaric acid-Q) and heat treatment under nitrogen (A) on the overall acceptance, odor and other quality properties related to these properties were determined in watermelon juices. For this purpose, aroma analysis, sensory analysis, amino acid, fatty acid, lycopene, β-carotene, hydroxymethyl furfural (HMF), furfural and color analyses were performed on the samples. The relationships between some aroma compounds and sensory properties of watermelon juice were evaluated by partial least squares regression (PLS-R) analysis. As a result of the optimization study carried out by determining the properties related to "odor" and "odor"/"general acceptance" (HMF, linolenic acid, nonadienol, nonenal, lycopene and leucine) as constraints, 84°C – 1 min was determined as the optimum heat treatment conditions (desirability value: 0.844). The effect of treatment time on nonadienol, nonenal and leucine, and the effect of temperature on HMF, linolenic acid and lycopene content are more pronounced. In terms of aroma profile, resin-applied samples are more similar to the fresh sample compared to the watermelon juice sample applied only heat treatment. It was determined that the watermelon juice sample with the most similar properties to the fresh watermelon juice sample was R2 among the resin-applied watermelon juice sample. Gallic acid added and A samples are also applicable when evaluated in terms of HMF, furfural, carotenoid components, aroma compounds and sensory properties. In order to reduce the undesirable odor occurring after heat treatment in watermelon juice, gallic acid addition (G1) can be preferred among the applications carried out within the scope of the study.