Evaluation of Accelerated Test Factors through the Development of Predictive Models in Vacuum-Packaged Compressed Biscuits

Abstract

Analysis of the physicochemical properties, bacteria numbers, and sensory quality of vacuum-packaged compressed biscuits (VCB) was conducted at room temperature and (or) elevated temperatures to ascertain the main deterioration indicator. The acid value (AV) was determined as the deterioration index and the limiting value was 3.28 mg g⁻¹. The deterioration curves of VCB between 45 and 85 °C were investigated and the changes of AV followed a first-order reaction. A modified Arrhenius model was selected for shelf life prediction (SLP). For analyzing the factors associated with prediction accuracy, the R², %RMS values of the prediction model, and the prediction errors of shelf life from accelerated shelf life tests (ASLT) were evaluated. The results showed that the number of replicates was the most important factor for prediction accuracy, followed by the time intervals for sampling and the number of points fitted for determining the deterioration curve. At the appropriate sampling interval, 9 points fitted in the AV change curves with three replicates were necessary. In the experimental design of ASLT, the results indicated that the number of temperatures had the greatest impact on the accuracy and at least one low temperature close to room temperature should be used when designing ASLT. However, for a long shelf life product such as VCB which the shelf life is more than 2 years, on the premise of prediction accuracy, taking into account the test cycle and cost, a certain number of relative higher temperatures (65, 75, and 85 °C) can be used in ASLT.