نشریه پژوهش های علوم و صنایع غذایی ایران
سال هفدهم شماره 6 (پیاپی 72، بهمن و اسفند 1400)

In this study, temperatures (40, 50, and 60°C), air velocity (3, 5, and 7 m/s) and pre-treatment (without pre-treatment, blanching, and microwave) were used as variables for investigation of antioxidant activity of dried artichoke leaves. The results revealed that variations in temperature and air velocity of the drying chamber and different pre-treatments significantly affected the free radical scavenging level and total phenol content in this plant. Based on the results obtained, it can be concluded that by increasing the temperature and air velocity and using blanching and microwave pre-treatments, the free radical scavenging level and total phenol content increased. The maximum percentage of free radical scavenging was 72.08% at 60°C and an air velocity of 7 m/s in the drying state by using microwave pre-treatment. The maximum total phenol content was 3.55 mg/g of dry matter at 60°C and an air velocity of 7 m/s in the drying state by using microwave pre-treatment.

Nowadays, probiotics have been seriously considered for their potential application in healthy food formulations. The most highlighted concern about probiotics is that the number of probiotic bacteria at the time of consumption may be lower than the required value (107 CFU/g). A new approach is the immobilization of probiotic cells in the matrix of edible films. So in this study, edible carboxymethyl cellulose (CMC) probiotic films containing Lactobacillus casei, and the silver carp muscle protein hydrolysates (SCMH) prepared by using limited Alcalase hydrolysis, were analyzed and the viability of bacterial cells was determined at 25, 4, and -18°C for 30 days. An alkaline solubilization/acid precipitation method was used to isolate silver carp white muscle proteins. Protein isolate (3%, W/V) was hydrolyzed with 5% E/S ratio (w/w) Alcalase at 50°C and pH 8.0 for 3 min. Briefly, films were prepared by dissolving SCMH and CMC powder (1.5%, w/v) in a ratio of 1:2 in distilled water and L. casei was added to a final concentration of 108 CFU/mL. Probiotics were counted at intervals of 1, 10, 20, and 30 day. The physical, mechanical [Ultimate tensile strength (UTS) and elongation at break (EB)], thermal and structural properties were determined. XRD patterns of the film samples collected by X-ray diffractometer (XRD) and Fourier transform infrared (FT-IR) spectroscopy of the film samples were recorded. The results indicated that the addition of SCMH significantly (p˂0.05) improved the L. casei viability at all three temperatures. Thickness, moisture absorption, and water vapor permeability (WVP) of the films were not influenced by addition of the probiotic. However, the addition of SCMH negatively affected the film’s mechanical properties. The FT-IR analysis confirmed the formation of hydrogen bonds between L. casei and the CMC matrix, the XRD and differential scanning calorimetry (DSC) analyses confirmed the plasticizing effect of SCMH on the films. Thus, CMC films containing L. casei showed the highest UTS (3.7 MPa) and EB (29.9%). Generally, the results indicated that the SCMH incorporated CMC-based film can be a good carrier for probiotics as bioactive food packaging system with promising potential for shelf life extension of perishable foods.

The drying of food can extend the shelf life of food, reduce transportation and storage costs. Fick's second law is commonly used to evaluate the mass data in the drying process in a standard way and is based on many assumptions. Understanding the meaning of mass transfer in products can improve the drying process and product quality. Computational fluid dynamics (cfd) models fluid flow situations utilizing powerful computer and applied mathematics in order to predict mass transfer in industrial processes. The aim of this research was numerical study of the drying behavior of pistachio nut using CFD method and evaluating the numerical results in the bed condition of fluid, semi fluid and fix bed as well as air temperatures of 90, 75, 60 and 45°C. During drying using computational fluid dynamic and the Fluent CFD code, the external flow and temperature fields around the cylindrical object (7.5× 10 millimeter) will be predicted in the numerical analysis.  A laboratory fluid bed dryer was used for drying experiments. The main parts of the dryer are forward radial fan, drying chamber, electrical heater, inverter, temperature controller. The dryer attachment tools are input and output temperature sensors, anemometer and computer. The numerical part was verified and juxtaposed with the experimental data. The numerical solution result at 60, 75 and 90°C were so close to experimental results except for air temperature of 45°C. Mean absolute error in fix bed, at 60, 75 and 90°C were 0.2123, 0.1257 and 0.0337 which were lower than 45°C temperature and R2 values for these temperatures were 0.9903, 0.9705 and 0.9807, respectively. As the temperature decreased, the values of Eabs and X2 increased in all bed conditions. The average value of R2 for all applied bed conditions was 0.9850. This value showed high correlation between experimental and numerical results.

The composition and biological activities of kombucha beverage depends on type of herbal tea, concentration of sucrose and the fermentation time. This study aimed to investigate the effect of different preparation conditions on antibacterial activity of heated kombucha beverages by Response Surface Methodology (RSM). Four types of herbal teas, including black tea, green tea, lemon verbena and peppermint were prepared with three concentrations of sucrose (2, 5 and 8%) and inoculated with active kombucha culture. After 7, 14 and 21 days, beverages were heated by autoclaving and their antibacterial activity against four bacteria including Escherichia coli, Shigella dysenteriae, Staphylococcus aureus and Bacillus cereus was evaluated by well method. The RSM was used to investigate the effect of sucrose concentration, fermentation time and type of herbal tea on antibacterial activity of heated beverages. Increasing sucrose concentration had significant effect (P<0.0001) on antibacterial activity of heated beverages against all tested bacteria. Increasing of fermentation time had significant effect (P< 0.0001) on antibacterial activity of heated beverages against E. coli and S. dysenteriae. Type of herbal tea had significant effect on antibacterial activity against S. aureus and S. dysenteriae. The highest antibacterial activity against E. coli and S. dysenteriae was observed in beverages prepared with lemon verbena. Beverages prepared with green tea showed highest antibacterial activity against S. aureus. The highest antibacterial activity against B. cereus was observed in heated beverages prepared with black tea and peppermint. In general, the results showed significant antibacterial activity of heated kombucha beverages against the tested bacteria.

The aim of the present study was to use the Maillard reaction as a means to glycosylate protein hydrolysates obtained from Cajanus cajan and to evaluate the effects of this chemical modification on antioxidant and emulsifying properties. Chemical properties, amino acid composition, and molecular weight distribution of the hydrolysates were evaluated. Glucose, galactose, and maltodextrin in the ratios of 1:2, 1:1, and 2:1 (hydrolysate: sugar, dry weight basis) were used for glycosylation. Antioxidant activity was evaluated by 1, 1- diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and nitric oxide scavenging. The sonication technique was used to prepare the (oil/water) emulsions. The droplet size distribution and zeta potential of the emulsions were measured during 4 days of storage. Results showed that glycosylation by glucose in the ratio of 2:1 increased DPPH scavenging activity from 37.96% to 85.53% and nitric oxide inhibition activity from 14.50% to 54.83%. Although glycosylation improved emulsifying stability of glycosylated hydrolysates compared to non-glycosylated hydrolysates, no significant difference was observed between the three examined sugars.

UF- Feta cheese is mostly produced from bovine milk and is usually consumed fresh or only after a short period of ripening (60 days). In this research, the influence of commercial starter cultures (SafeIT 2, FRC- 65 and R- 704) and ripening time (0- 60 days) on chemical (total solids, fat, protein, ash, salt, acidity, pH), biochemical (pH 4.6, TCA, PTA-soluble nitrogen, acid degree value) and sensory (color and appearance, aroma, texture, flavor and total acceptance) characteristics of UF- Feta cheese analogues was investigated. According to our results, the starter culture types were known to have a significant effect (P≤ 0.05) on pH, %salt, %protein, and pH 4.6- soluble nitrogen of cheeses, whereas the other chemical properties were not affected by them. Ripening time only significantly (P≤ 0.05) influenced %acidity, pH, %salt, acid degree value (meq acid 100 g-1 fat), %protein and %proteolysis products of samples. Also, the starter culture and ripening time did not affect the sensory properties significantly, excluding color and appearance, however, the produced cheeses from SafeIT 2 had higher sensory scores compared with the others containing FRC- 65 and R- 704 cultures.