Effects of a commercial scale intervention system combining ultraviolet (UV)-C and plasma treatments on the microbial decontamination of black pepper powder were investigated. The process parameters include treatment time, time for plasma accumulation before treatment, and water activity of black pepper powder. A significant reduction in the number of indigenous aerobic mesophilic bacteria in black pepper powder was observed after treatments lasted for ≥ 20 min (p<0.05) and the reduction was differed by powder manufacturer. The microbial reduction rates obtained by individual UV-C treatment, individual plasma treatment, and UV-C/plasma-combined treatment were 0.2, 0.5, and 1.0 log CFU/g, respectively, suggesting that the efficacy of the microbial inactivation was enhanced by treatment combination. Nonetheless, neither plasma accumulation time nor powder water activity affected the microbial inactivation efficacy of the combined treatment. The UV-C/plasma-combined treatment, however, decreased lightness of black pepper powder, and the decrease generally increased as operation time increased. The plasma accumulation time of 20 min resulted in significant reduction in both lightness and brown color. The results indicate that the commercial-scale intervention system combining treatments of UV-C and plasma has the potential to be applied in the food industry for decontaminating black pepper powder.

Edible biopolymer films were developed from the exopolysaccharides (EPS) extracted from Weissella confusa 113-2. The optimum composition for film formation was determined using the response surface analysis with the explanatory variables of the EPS (0.5-5.5%) and glycerol (0.5-5.5%) concentrations and the response variable of film elastic modulus (EM). The mass ratio of distilled water to solids was set constant (14:1). Tensile strength (TS), percentage elongation at break (%E), EM, water vapor permeability (WVP) of EPS films were evaluated. The glass transition temperatures of the films were also determined by a dynamic mechanical analysis. The optimum mass ratio of EPS to glycerol was 0.754:0.375. The WVP, TS, %E, and EM of the film under the optimal composition were 3.53±0.21 g·mm/kPa·h·m2, 7.03±0.49 MPa, 84.82±12.31%, and 62.03±6.93 MPa, respectively. The glass transition temperature varied from 54 to 83 °C. The EPS film has the potential to be applied to food products as an edible film with physical and barrier properties comparable to other biopolymer edible films.

The release profiles of nisin from nisin-incorporating gel foods and the antimicrobial activities of the gels on the growth of Brochothrix thermosphacta in an aqueous system containing the gels have been investigated. A linear regression model was applied to determine the diffusion coefficient (D) for the diffusion of nisin in the gel. The antimicrobial activities of nisin released from 1, 2 and 3% (w/v) agar gels on the growth of B. thermosphacta in a broth medium with and without nisin were investigated. The D decreased from 1.2×10 -2 to 8.2×10 -3 and 6.4×10 -3 cm 2 /s as the agar concentration in the gel increased from 1 to 2 and 3% (w/v), demonstrating the diffusion rate in the gels can be controlled by the agar concentration in gel. The agar gel incorporating nisin inhibited the B. thermosphacta growth in the broth medium by prolonging the lag phase. The growth inhibition was enhanced by the addition of nisin in the medium. The results of this study exhibited that the gel food is a feasible nisin delivery system with a controlled release achieved by the adjustment of agar concentration in the system, demonstrating the potential of nisin-incorporating gel for preserving particulate-containing drinks.

Strawberry jelly as a universal design food was developed using strawberry juice (SJ), sugar, xanthan gum (XG), and locust bean gum (LBG). Experimental variables included SJ concentration (30-40% (w/w)), sugar concentration (7.5-10.0% (w/w)), and the ratio of XG/LBG (0.3-4.0% (w/w)), and response variables were textural (hardness, gumminess, chewiness) and color properties. The formulation of strawberry jelly was optimized against hardness and the interactions among variables were predicted using the response surface methodology. Controlled storage test at 5 or 15°C was conducted to determine the values of the jelly at different temperatures. The optimal SJ and sugar concentrations and the ratio of XG/LBG against hardness were 40, 10, and 1.5%, respectively. The color did not change significantly during storage at 5 and 15°C (p>0.05). However, the textural characteristics during storage increased significantly at 5°C (p<0.05) and the hardness was appropriate to be used as a criterion for determining the shelf life of the jelly. The shelf life at 5°C generated from a zero-order kinetics (R²=0.96) was 40 d according to a criterial value, 1.8 N, of hardness. The Q10 value was calculated as 0.6, which allowed prediction of the shelf life values at different temperatures. The results from this study suggested a formulation of strawberry jelly as a universal design food and allowed determination of the shelf life of the food product.

Effects of dielectric barrier discharge atmospheric cold plasma (DACP) treatment on the inhibition of Salmonella and the storability of grape tomato were investigated. Grape tomatoes, with or without inoculation with a cocktail of three strains of Salmonella (~8 log CFU/g tomato), were packaged in a polyethylene terephthalate commercial clamshell container and cold plasma-treated at 35 kVat 1.1 kHz for 3 min using an DACP treatment system equipped with a pin-type high-voltage electrode. DACP treatment resulted in ~1 log CFU/tomato reduction of Salmonella, irrespectively of the size of container (316, 595vs. 758 cm3), the number of grape tomatoes in the container (3, 7, vs. 11), and the position of the tomato in the container(P > 0.05).Rolling integrated during treatment significantly increased the Salmonella reduction rates to 3.1±0.3 and 3.3±0.8 log CFU/tomato in the single-layer and double-layer configurations of the tomato samples in the container (992 cm3), respectively. Rolling-adopted DACP initially reduced the number of total mesophilic aerobes and yeast and molds in the double layer configuration of tomato samples by 1.3±0.3 and 1.5±0.2 log CFU/tomato, respectively, without altering the color and firmness of the tomatoes. The growth of Salmonella, total aerobes, and yeast and molds on DACP-treated grape tomatoes was effectively prevented during storage at 10 °C. DACP treatment did not influence the tomato color index (a*/b*), firmness, weight loss, pH, total soluble solid content, and lycopene concentration of grape tomatoes at 10 and 25 °C (P> 0.05). DACP treatment holds promise as a post-packaging process for improving microbial safety against Salmonella and storability of fresh grape tomatoes.

A microencapsulated cinnamon oil (CO)-coated film was developed using a pilot-plant scale film coating system. CO microencapsulated with polyvinyl alcohol was incorporated with a printing ink and the ink mixture was applied to the surface of a polypropylene (PP) film as an ink coating using a gravure printing press at a speed of 20-200 m/min. The tensile strength, percentage elongation at break, elastic modulus, and water vapor permeability of the PP films with and without coating with the microcapsules were not significantly different (p > 0.05), which indicates that the coating did not alter those properties of the films. Microencapsulation effectively prevented the volatilization of CO in the films. The microencapsulated system may be extended to other food-packaging films for which the same ink-printing platform is used. The results from this study imply that the oil-microencapsulated films could be potentially produced by a modern film manufacturing system.

The methods for determining the diffusion parameters for the diffusion of d-limonene, a major volatile compound of orange juice, through a multi-layered food packaging material and predicting its absorption into the packaging material have been investigated. The packaging material used was the 1.5-mm thick multi-layered packaging material composed of high impact polystyrene (HIPS), polyvinylidene chloride (PVDC), and low density polyethylene (LDPE). Orange juice was placed in a cell where volatiles were absorbed in the sample package and kept at 23±2oC for 72 hr. The d-limonene absorbed in a 1.5-mm thick multi-layered food packaging material was analyzed by a solid phase micro-extraction (SPME). The absorption parameters for the absorption of d-limonene in the packaging material were determined and absorption of d-limonene into the packaging material was predicted using absorption storage data. The SPME desorption at 60oC for 1 hr resulted in the most sensitive and reproducible results. The diffusion coefficients of d-limonene in the packaging material and the partition coefficient at 23±2oC were approximately 1-2×10-12m2/s and 0.03, respectively. The absorption profile no earlier than 30 hr was fit well by a model derived from the Fick’s law.