Application of hurdle technology in a model system for selected rice-based products

Hurdle technology or combined methods of preservation was used in predicting and assessing food quality of espasol and tikoy. Model systems with hurdles such as three levels of water activities (0.908-0.903, 0.840-0.870, and 0.8000-0.850), two levels of pH (4.6 and 5.2) and three kinds of oils (coconut, coco:corn, and corn) were placed in different storage temperatures (7 deg, 30 deg and 38 deg C). The SAS System was used for ANOVA and DMRT to observe if there is a significant combined effect of these parameters on the free fatty acid content (FFA), acid value (AV) and peroxide value (PV) during the 12-week storage period of the product. Values were predicted through the Response Surface Methodology program. Quadratic equations were linearized for better scaling and for visual enhancement of the 3-D plots. Samples with aw 0.903-0.908 coconut oil, and stored in elevated temperature gave the highest FFA value. Coconut oil is more susceptible to hydrolytic rancidity than corn oil. This was directly proportional to AV since this was only multiplied by a factor of 1.99. Samples with aw 0.8000-0.8500, pH 5.2 corn oil, and stored in elevated temperature gave the highest PV. Corn oil is more prone to oxidative rancidity than coconut oil. Elevated temperature affected the rate of chemical deterioration. Water activity used and the temperatures in which the products were stored had an effect in mold counts. The highest count was obtained in the sample with the highest water activity at room temperature and the lowest count was obtained in the samples with the lowest water activity and stored at refrigerated temperature. Model B had the most optimum combination of parameters. These parameters were applied to the prepared espasol and tikoy. The prepared tikoy lasted 3 days longer than those availed commercially while the prepared espasol lasted 2 days longer than the one bought locally. Storage of both of these samples at refrigerated temperature also increased its shelf-life. In all the samples, microbial deterioration was first to set in than the commercial deterioration. Results obtained showed great potential for the prepared models in predicting and assessing food quality of not just rice-based products but other foods of similar composition.