Development of a Novel Image Analysis Technique to Detect the Moisture Diffusion of Soybeans [Glycine max (L.)] During Rehydration Using a Mass Transfer Simulation Model

Developing a novel method to measure texture changes of semi-solid food during a continuous compressive motion with high deformation using repeatable dual extrusion cell (RDEC)

Mechanical changes during mastication are difficult to evaluate without using a novel method because the size of the sample is continuously and randomly reduced. The repeatable dual extrusion cell (RDEC) has been developed to measure the breakdown characteristics of a semi-solid food (i.e., minced pork gel) from initial solid states to a small particle size during repeated high deformation compressive motions. The force-time curve of RDEC was recorded, followed by a calculation of work values for each cycle and fitted by Peleg's model. The decrease of k₁ (1.7-1.19) and k₂ (1.56-1.42) values in Peleg's model with an increase of moisture content (56.5-62.5 %) indicated the easily deformable characteristics of soft food. During RDEC measurement, as long as the characteristic length of the sample was larger than the diameter of RDEC probe hole (>4.5 mm), the initial sample size showed no significant influence (p < 0.05) on the measurements. RDEC demonstrated similar ratios of particulate size with human subjects up till 20 cycles of processing. The equilibrium force value from RDEC and SEM images demonstrate that the connective tissue in pork gel mainly contributed to the end-product texture properties after continuous mastication. This study provided an application of the novel RDEC device to estimate the texture and structural changes of minced pork gel under a continuous high deformation compressive motion.

Effects of Low-Temperature Drying with Intermittent Gaseous Chlorine Dioxide Treatment on Texture and Shelf-Life of Rice Cakes

We investigated the effect of chlorine dioxide (ClO2) under low temperature drying to suppress rice cake stickiness during the cutting process by initiating the onset of retrogradation until the stickiness is minimized for shelf-life extension. The intermittent ClO2 application at low-temperature drying was conducted at 10 °C for different drying periods (0, 6, 12, 18, and 24 h). Texture analysis showed significant differences with increasing values of hardness (901.39 ± 53.87 to 12,653 ± 1689.35 g) and reduced values of modified adhesiveness (3614.37 ±578.23 to 534.81 ± 89.37 g). The evaluation of rice cake stickiness during the cutting process revealed an optimum drying period of 18 h with no significant difference (p ≤ 0.05) compared to the 24 h drying process. Microbial contamination during the drying process increased, with microbial load from 6.39 ± 0.37 to 7.94 ± 0.29 CFU/g. Intermittent ClO2 application at 22 ppm successfully reduced the microbial load by 63% during drying process. The inhibitory property of ClO2 was further analyzed on a sample with high initial microbial load (3.01 ± 0.14 CFU/g) using primary and modified secondary growth models fitted to all experimental storage temperatures (5–25 °C) with R2 values > 0.99. The model demonstrated a strong inhibition by ClO2 with microbial growth not exceeding the accepted population threshold (106 CFU/g) for toxin production. The shelf-life of rice cake was increased by 86 h and 432 h at room temperature (25 °C) and 5 °C respectively. Microbial inactivation via ClO2 treatment is a novel method for improved food storage without additional thermal sterilization or the use of an additional processing unit.