Effect of Storage Time on the Physical, Chemical, and Rheological Properties of Blueberry Jam: Experimental Measurements and Artificial Neural Network Simulation

Abstract

The present work aimed to develop different formulations of blueberry jam (traditional and light) made from rabbiteye fruits (Powder Blue and Climax varieties) and then analyze the influence of storage on their physicochemical and rheological properties at different times: (i) zero time (i.e., freshly processed), (ii) after 30 days, (iii) after 90 days and (iv) after 120 days. The influence of storage time on these properties of the jams was analyzed using statistical analysis (ANOVA and Tukey test) and regression. The physical, chemical and rheological properties were predicted by mathematical simulation using independent variables composed of molecular descriptors + SMILES codes. It also used time (days), % water, % citric acid, % glucose, % sucrose, % anthocyanin, % HM pectin, % LM pectin, % xanthan gum, pH and acidity (%), as independent variables. Several architectures of three and four layers for learning were tested, encompassing testing and prediction steps in order to predict the dependent variables of hardness, water activity, and adhesiveness. According to the results, higher sucrose concentrations and longer cooking times showed greater anthocyanin instability in products made with HM pectin (i.e., in traditional products). In the same way, there was no influence of the storage time on soluble solids content in light jellies (made with LM pectin). Regarding the rheological properties, it was noted that time influenced the hardness of the jellies, except for the traditional formulation with pectin extracted from the passion fruit peel (highly hydrated). However, adhesiveness was influenced by time in all products. The lowest deviations for the dependent variables were obtained, finding the optimal configuration of 10-30-10-3 architecture. The lowest deviations for the dependent variables were obtained, finding the optimal configuration of 10-30-10-3 architecture.