The accelerated life testing (ASLT) method was used to evaluate the effect of increasing the storage temperature from 10 to 40 °C on the aerobic plate count (APC), the pH, and the colorimetric parameters (L*, a*, b*) of pasteurized orange juice during 40 days of storage. For APC growth, a polynomial model was found to fit better, and at the lower temperatures of 10 and 15 °C, the shelf life was longer, as expected. More specifically, 15 and 10 days were needed, respectively, until the rise in the APC population to 1000 cfu/mL. However, for the temperature range of 30–40 °C, only approximately 3 days were needed to reach 1000 cfu/mL APC. Regarding pH, according to an exponential 3P model, a stable trend was apparent at all temperatures until 30 days of storage, followed by a more abrupt decreasing trend at 25 °C. The lightness (L*), redness (a*), and yellowness (b*) of the juice showed a decreasing trend with the temperature increase, and this trend was more profound at higher temperature levels. The multiple regression analysis between the predictors L*, a*, b*, pH, storage temperature, and the APC response showed an increase in APC growth when the colorimetric parameters decreased and the temperature increased.

Pectin and polyphenols have been obtained from choice peach flesh using microwave extraction, with the resulting extracts used in functionalizing strained yogurt gels. A Box-Behnken design was utilized in order to co-optimize the extraction process. Soluble solid content, total phenolic content, and particle size distributions were measured in the extracts. Extraction at pH 1 yielded the highest phenolic content, while increases in the liquid-to-solid ratio resulted in a decrease in soluble solids and an increase in particle diameter. Selected extracts were then incorporated into strained yogurt, and the resulting gel products were assessed for color and texture over a two-week period. All samples were darker and had more red tones than the control set yogurt, while exhibiting less yellow tones. The cohesiveness of all samples remained stable over the gels’ aging of two weeks (break-up times always remaining within 6 s and 9 s), which is close to the expected shelf-life of such products. The work required for the deformation of most samples increases with time, indicating that the products became firmer due to the macromolecular rearrangements in the gel matrix. The extracts obtained with the highest microwave power (700 W) give less firm samples. This was due to the microwave-induced loss of conformation and self-assembly of the extracted pectins. The hardness of all samples increased over time, gaining from 20 to 50% of the initial hardness due to the rearrangement of the pectin and yogurt proteins over time. The products with pectin extracted at 700 W were again exceptions, losing hardness or remaining stable after some time. Overall, this work combines the sourcing of polyphenols and pectin from choice fruit; it uses MAE for isolating the materials of interest; it mechanically examines the resulting gels; and it performs all the above under a specifically-set experimental design aiming towards optimizing the overall process.

The sensory acceptability rate of pasteurized orange juices stored at different temperature levels was evaluated using a large-scale experiment with untrained consumers and an accelerated shelf-life testing method. Pasteurized orange juice samples were stored at 10, 20, 30 and 40 °C and tested for acceptance or rejection at consecutive time points using a reverse product preservation plan. From a total of 504 samples and the participation of 72 consumers, 155 failures and 109 passes were recorded. Due to the large number of samples (28) selected for testing from each consumer, a balanced incomplete block design was adopted to facilitate a very small number for evaluation (7 for each consumer) with minimal reduction in the reliability of the experiment and results. As expected, there was a gradual increasing trend of rejections at all temperature levels by time. Also, it was observed that pasteurized orange juices tended to be rejected by consumers at approximately 3 days before they would be microbiologically unsafe for consumption. Also, it was shown from the risk rate trend that higher storage temperatures are linked with very early perceptiveness of sensory defects during nearly the first 100 h of preservation. The present work constitutes essentially a very useful tool for the industry because it enables the proper adjustment of shelf life including both sensory and microbiological parameters, which results in fewer returned and deteriorated products.