Volume 15, Issue 7 -

The numerical simulation model of forced-air cooling of strawberries in a clamshell and a box was established by using computational fluid dynamics method. The cooling process of the simulation and the experiment results agreed well in different conditions, indicating that the simulation model was validated. The results showed that the 7/8 cooling time was 180 min, 135 min, 108 min and 100 min and the cooling uniformity coefficients were 0.31, 0.22, 0.24, 0.26 when the diameters of B-vent(the vent on the box) were 30 mm, 40 mm, 50 mm, 60 mm, respectively. The 7/8 cooling time decreased and the cooling uniformity coefficient improved, when the shape of C-vent (the vent on the clamshell) changed from round to rectangular. The 7/8 cooling time also deceased and the cooling uniformity coefficient increased, when the area of C-vent with both round and rectangular shapes increased. These results indicate that both B-vent and C-vent had significant effect on reducing the cooling time and the improving cooling uniformity for strawberries, It is suggested that the optimized vent ratio of B-vent (the diameter is 40 mm) and C-vent (15 mm round or 20 mm × 15 mm rectangular) for the current commercial packaged strawberries were 9.4 % and 8.5 %, respectively.

Antimicrobial films were prepared by incorporating nano-titanium dioxide (TiO 2 ) modified by silane into soy protein isolate (SPI) films. The effects of different concentrations of modified nano-TiO 2 (TiO 2- NM) on the physical properties, antimicrobial properties, and microstructure of the SPI-based films were investigated. Attenuated total reflectance Fourier-transform infrared spectroscopy indicated that the interaction between the SPI and TiO 2 -NM was via hydrogen bonds. Scanning electron microscopy and atomic force microscopy both showed that the microstructure of SPI-based films with TiO 2 -NM was compact. Moreover, as the content of TiO 2 -NM increased from 0 to 1.5 g/100 mL, the water vapor permeability and oxygen permeability were decreased from 5.43 to 4.62 g· mm/m 2 d· kPa and 0.470 to 0.110 g· cm −2 · d −1 , respectively. An increase from 6.67 MPa to 14.56 MPa in tensile strength and a decrease from 36.53% to 27.62% in elongation at break indicate the optimal mechanical properties of all groups. TiO 2 -NM films had excellent UV barrier properties, with a whiter surface with increasing TiO 2 -NM content. In addition, the SPI-based films with TiO 2 -NM showed antimicrobial activity, as evidenced by an inhibitory zone increasing from 0 to 27.34 mm. Therefore, TiO 2 -NM can be used as an antimicrobial agent in packaging films.

Kefir drink is a source of probiotic microorganism with remarkable functional and technological properties. The objective of this work is to isolate yeast strains from Malaysian kefir drink and evaluate them for probiotic potentials. In the present study, nine strains of probiotic yeast were isolated from a Malaysian kefir drink and identified according to their 16S rDNA sequences. Furthermore, their probiotic potential was evaluated. The probiotic properties were tested for aspects of antibiotic susceptibility, antimicrobial activity, and gastrointestinal condition tolerance (pH and temperature). Five isolated strains, M3, Y5, Y9, Y11 and A1, showed good tolerance towards low pH condition while three strains, A1, M1, and M3, showed antimicrobial activity against E. coli, P. aeruginosa , and Salmonella sp. Most isolates were resistant to penicillin, streptomycin, and ampicillin, and grew well at human body temperature. The result of this test indicates that the yeast strains isolated from Malaysian kefir drink have excellent potential for use as probiotics in various products. Lastly, kefir milk is one of the excellent source of probiotic yeast strains and could be used as a new yeast probiotic formulation or in food supplements.

The aims of this research were to examine the effect of pH on extraction of proteins from mahaleb ( Prunus mahaleb L.) kernels, and to investigate the functional properties of resulting protein concentrate. The optimum pH values for the protein extraction and precipitation were determined as 10.0 and 4.5, respectively. The protein concentrate containing 92.73% dry matter, 6.29% ash, 6.02% carbohydrate, 1.42% fat and 73.11% protein was produced by using these extraction and precipitation pH values. Water-holding capacity, oil-holding capacity and the least gelling concentration of the protein concentrate were 2.81 g water/g, 1.66 g oil/g and 12%, respectively. Moreover, emulsifying activity and stability indices, foaming capacity and stability of protein concentrate were 27.21 m 2 /g, 81.05 min, 43.75% and 71.33% (after 30 min), respectively. The functional and chemical properties of the protein concentrate indicate that it may find application as functional ingredient for various food products.

Identification of edible oil adulteration is an essential task for oil quality control. In this study, the adulteration of sesame oil samples with soybean oil was detected by low-field nuclear magnetic resonance (LF-NMR) combining with chemometrics including principal component analysis (PCA), partial least squares (PLS) and principal component regression (PCR) methods. PCA analysis was applied for the classification of various adulteration ratios of sesame oil samples. PLS and PCR were used for the detection of adulteration ratios of sesame oil samples. A calibration data set was established and evaluated by a cross-validation method. The correlation coefficients between actual and predicted values for the calibration and validation data sets were 0.953 and 0.973 for PLS and 0.975 and 0.979 for PCR, respectively. Therefore, a combination of LF-NMR with chemometrics can be applied for detecting sesame oil adulteration in a fast and nondestructive manner.

In this work a two-dimensional convective drying model of heat, mass and momentum transfer is developed taking account of the shrinkage and the quality degradation of carrots. The kinetics of β-carotene degradation in dried agricultural product is considered to follow a first-order reaction. Temperature dependence of the reaction rate constants followed the Arrhenius relationship. The developed model, describes the strong coupling between mass, heat and momentum transfers, shrinkage and quality (β-carotene) changes and takes into account the dehydration of the solid caused by a temperature increase.

This study aimed to produce betalain-rich powders by spray drying red beet extract using modified starch and maltodextrin blends as carrier materials, as well as to investigate the product storage stability as affected by water sorption and light exposure. The influence of spray drying conditions and carrier blends on the process yield, water content and solubility of the powders, betalain retention, and color parameters was assessed using a central composite design 2 4 . The results of this screening allowed selection of four samples to further evaluation concerning their morphological characteristics, particle size distribution, water sorption properties, and betalain stability under light exposure. Samples formulated with carrier blends composed of equal amounts of modified starch and maltodextrin, used in a concentration of 35 g carriers/110 g of initial solution resulted in the higher betalain stability during 98 days of storage under exposure to light. Even though this formulation showed similar water sorption behavior to the other formulations studied, it also showed the best mechanical properties, indicating lower susceptibility to powder collapse.

For the first time, the modified supercritical carbon dioxide extraction (MSCE) of biologically active compounds from Feijoa sellowiana leaves was investigated. Total yield (TY) and bioactivity of biocompounds in terms of DPPH • (%DPPH sc ) and HO • (%HO sc ) radicals scavenging were maximized via multivariate optimization. The optimized conditions were the pressure of 272.34 bar, supercritical carbon dioxide flow rate of 1.58 mL min −1 , temperature of 52.48 °C, and dynamic extraction time of 110.62 min. The predicted values of the TY, %DPPH sc , and %HO sc were 81.12 mg g −1 , 85.16 %, and 75.66 %, respectively. The chromatographic analysis demonstrated gallic acid as the main biophenolic (136.20 ± 0.16 mg g −1 ). The scanning electron microscopy images showed dramatic disruption of cells treated with MSCE. A comprehensive comparison was made between current findings and other techniques (conventional and ultrasonic waves assisted extraction). More TY was achieved using conventional method but the bioactivity of MSCE products was considerably better.