Combined use of vacuum impregnation and encapsulation technologies for phenolic enrichment of strawberries.

Plant-based phenolic extracts have gained significant attention in the food industry due to their antimicrobial and health-promoting effects. However, their usage is limited because of poor water solubility and instability during processing. Therefore, encapsulation of phenolics with a suitable carrier system is essential for overcoming these problems and increasing their application in food products. In this study, encapsulated phenolic extracts were used for the first time in vacuum impregnation (VI). For this purpose, different phenolic extracts (cinnamon, turmeric, pomegranate peel) were obtained from the plant source. PPE was selected because it has the highest total phenolic content, antioxidant capacity, and antimicrobial activity against Botrytis cinerea. Then, PPE was encapsulated with different emulsifiers (T80, GMO, IN, WPI, and LEC). After the characterization and stability studies were performed, PPE encapsulated with T80 was used to produce a functional strawberry snack by VI technology. The results showed that the diffusion rate of EPPE was significantly increased compared to the control and PPE-VI group. EPPE-enriched strawberries were the preferred snack with high-quality characteristics.

The effects of the novel home freezing system on microstructure, color, antioxidant activity, and microbiological properties of strawberries.

In these days people are more interested in frozen foods, especially home freezing fruits and vegetables. In this study, the effects of a new developed quick freezer system for home-type refrigerator on the freezing rates and some quality properties of strawberries were investigated. The freezing cabinet (at -30 °C with 1.2 ms-1 air) was designed and manufactured by Bosch und Siemens Hausgerate GmbH (Çerkezköy, Turkey) then the strawberrries were frozen in a novel quick freezer and compared with the samples frozen statically at classic home type refrigerator (at -18 °C without any air blown) via the freezing times at three different (bottom, middle and top) position. Microstructure, color, antioxidant content and microbiological quality during storage of 4 months at -25 °C compared. Strawberries reached -15 °C approximately 234 min shorter in the novel system. Freezing rates were determined as 0.32 cm h-1 for the static freezer and 1.51 cm h-1 for the quick freezer. Unlike the classic home-type refrigerator, quick freezing process took place in the novel home freezing system. SEM images showed that higher freezing rate in the novel system provides better protection in tissue structure and cell walls. The antioxidant activity of the strawberries frozen in the novel home freezing system was 8.96% higher after the freezing process. Brightness and redness of samples were protected better after quick freezing during storage. Nonetheless, no evident differences were observed in microbiological criteria.

Production of prebiotic 6-kestose using Zymomonas mobilis levansucrase in carob molasses and its effect on 5-HMF levels during storage.

Fructooligosaccharides have important potential use in the food industry due to their properties such as solubility in water, stability in acidity of fruit juices and during storage, low-calorie value and prebiotic effects. In this study, for the first time, Zymomonas mobilis levansucrase was used for in situ 6-kestose production in carob molasses. The produced kestose was stable during storage at 20 °C for 4 months. The product was evaluated for color, non-enzymatic browning index and titratable acidity during storage and the quality of the product was found comparable to that of control. Furthermore, the decreased amount of sucrose resulted in the prevention of 5-hydroxymethylfurfural (5-HMF) formation during storage. As a result, carob molasses was converted into a high-quality prebiotic product with decreased sucrose content and reduced 5-HMF quantities, and a new method was developed to prevent 5-HMF formation in fruit juices and molasses.

Ultrasound as pretreatment for drying garlic slices in microwave and convective dryer.

The effects of ultrasound pretreatment (US) before hot air drying (HAD) and microwave drying (MWD) of garlic slices were investigated. For this aim ultrasonic bath at 30 °C for 30 min (35 kHz), microwave oven at 540 W power and tray dryer at 60 °C and with 1.0 m/s air flow rate were used to reach the final moisture content of 5%. Drying rate increased in the US + HAD and the US + MWD groups by 19.30% and 13.82% respectively in comparison with control groups. The effective moisture diffusivity (Deff) of garlic slices were calculated from Fick's diffusion model for the HAD, US + HAD, MWD and the US + MWD groups as 1.420 × 10-10, 1.826 × 10-10, 1.177 × 10-8, 1.363 × 10-8 m2/s respectively. The rehydration rates increased, and bulk densities were decreased in the US + HAD and the US + MWD compared to the control groups. The color values were significantly affected after ultrasound pretreatment. Redness, and yellowness increased most in the US + HAD group.

Influence of ultrasound and osmotic dehydration pretreatments on drying and quality properties of persimmon fruit.

In this study, the effect of the ultrasound and osmotic dehydration pretreatments before the convective drying of the persimmon fruit was assessed via their drying behavior and quality properties. Ultrasound-assisted osmotic dehydration (30 °C, 45 °Brix) was performed at 35 kHz for 10, 20, and 30 min. Afterward, samples were placed first in 45 then in 70 °Brix sucrose solutions; the solutions were next shaken at 100 rpm. The control group without ultrasound treatment dehydrated osmotically. The samples were dried in a tray drier at a temperature of 60 °C and an air velocity of 1.5 m/s. Ultrasound-assisted osmotic drying treatments increased water loss and sugar gain; moreover, the osmotic dehydration time was shorter than in the untreated group. The ultrasound-assisted osmotic dehydration demonstrated a significantly decreased drying time, increased drying rates, and a 21% increase in effective water diffusivity by 30 min. The ultrasound pretreated osmotic dehydration prior to hot air-drying decreased the total required drying time. The ultrasound-assisted osmotic dehydration affected the rehydration rate and total phenolic content significantly and there was no significant difference between the color change (ΔE, ΔC, and Hue°) of the ultrasound treatment (30 min) group and the untreated group.

Decontamination of fresh-cut cucumber slices by a combination of a modified chitosan coating containing carvacrol nanoemulsions and pulsed light.

In this study, the impact of the combination of pulsed light (PL) treatments with antimicrobial coatings, consisting of modified chitosan suspensions incorporating carvacrol nanoemulsions, was investigated on the decontamination of fresh-cut cucumber slices. The upper surface of the cucumber slices, with or without the coating deposition, was inoculated with Escherichia coli ATCC 26 to reach a final concentration of 107CFU/g of the vegetable. PL treatments were conducted at different fluence (4, 8, and 12J/cm2) on the inoculated surface of cucumber slices. Results showed that the microbial reduction was only marginally affected by the coating formulation. A slight increase was observed when the carvacrol nanoemulsions were embedded in the chitosan matrix, but microbial reduction levels remained always below 1log cycle. In contrast, the different PL treatments resulted in a statistically significant increase in inactivation with increasing the treatment fluence, reaching 2.6log cycles at the maximum fluence. Remarkably, the combination of the antimicrobial coating with the most intense PL treatments resulted in a strong synergistic effect. For example, by combining a PL treatment at 12J/cm2 with one of the antimicrobial coatings a microbial reduction >5log cycles was reached. Therefore, it can be concluded that the combination of antimicrobial coatings and PL treatment is a promising method for surface decontamination of fresh-cut vegetables, which could be exploited in view of ensuring their microbiological safety.

Chitosan as a novel clarifying agent on clear apple juice production: Optimization of process conditions and changes on quality characteristics.

In this study, the use of chitosan as a clarification agent in the production of clear apple juice (AJ) was investigated, the optimum conditions were determined using RSM, and the effects on the quality of AJ were analyzed during storage at 4°C and 20°C for 4months. Optimum conditions for clarifying the AJ were chitosan concentration of 191.6mg/100ml juice, the process temperature of 20°C and process time of 30min. Changes in quality characteristics such as turbidity, pH, acidity, color, total monomeric anthocyanin, total phenolic, and protein contents were evaluated and compared to traditional clarification. Alicyclobacillus acidoterrestris causes significant safety issues in fruit juice industry; therefore also the antimicrobial effect of chitosan on A. acidoterrestris during the clarification process was examined. The results showed that clear AJ production can be achieved by the clarification step with direct chitosan addition, without the need for enzymatic treatment. However, the microbial reduction of A. acidoterrestris during the clarification process was not found to be significant.

Clarification of pomegranate juice with chitosan: changes on quality characteristics during storage.

In this study, for the first time, the use of chitosan as a clarifying agent in the production of clear pomegranate juice was evaluated and its effects on quality characteristics of juice were investigated. A central composite face centered design was used to establish the optimum conditions for clarification of pomegranate juice (PJ) using response surface methodology. The three factors were concentration of chitosan (10-120 mg/100ml), process temperature (10-20°C), and process time (30-90 min) and their effects on turbidity and a(∗) values were investigated. Using a desirability function method, the optimum process conditions were found to be 68.93 mg/100ml chitosan at a process temperature and time of 10°C and 30 min, respectively. PJ was produced using the optimum conditions and the quality characteristics such as turbidity, colour characteristics (L(∗), a(∗), b(∗), C(∗)), titratable acidity, total phenolic, monomeric anthocyanin, and protein contents were evaluated during storage at 4 and 20°C for 6 months.

Optimization of ohmic heating applications for pectin methylesterase inactivation in orange juice.

Ohmic heating (OH) which is among to electro-thermal methods and helps to inactivate microorganisms and enzymes was used in this study as thermal treatment on orange juice production for pectin methylesterase (PME) inactivation. Response surface methodology (RSM) was used for optimization of OH conditions. The effects of voltage gradient and temperature (independent variables) were investigated on PME activity (response) of orange juice. After optimization orange juice was produced and compared with untreated control juices and conventional thermally heated juices on the aspect of PME inactivation and some quality characteristics. Reduction of PME activities was found approximately 96 % in OH groups where conventional thermally heated juice has 88.3 % reduction value. Total pectin content was increased 1.72-2 % after OH applications. Ascorbic acid contents of OH samples were found between 43.08-45.20 mg/100 mL where conventional thermally heated juice has 42.9 mg/100 mL. As a result, it was determined that OH can be applied as a thermal treatment on orange juice production in moderate temperatures for PME inactivation and may improve functional properties of orange juice.

Levan production by Zymomonas mobilis in batch and continuous fermentation systems.

Levan production in batch and continuous fermentation systems by Zymomonas mobilis B-14023 was investigated. The culture medium used in both of the fermentation systems contained sucrose and various organic nitrogen sources. Maximum concentration of levan was produced with yeast extract among the nitrogen sources tested. Response surface methodology was used to investigate the effects of three factors on the concentration of levan in batch cultures of Z. mobilis. Maximum levan concentration was 40.2 g/L and this concentration was reached at the optimum levels of process variables, which were 299.1 g/L initial substrate concentration, 42.3 h incubation time, and initial pH 6.0. Continuous fermentation experiments were done in packed bed bioreactor using Ca-alginate immobilized Z. mobilis cells. The highest levan concentration (31.8 ± 0.21 g/L) was obtained at a dilution rate of 0.14 h(-1) while maximum volumetric productivity (6.556 g/(Lh)) was obtained at a dilution rate of 0.22 h(-1). Increasing the dilution rate resulted in decreased levan and increased residual sugar concentrations.

Yield and quality effects of electroplasmolysis and microwave applications on carrot juice production and storage.

Electroplasmolysis as a pretreatment and microwave heating as an alternative to traditional heating were used in carrot juice production and the effects of these electrical methods on juice quality were investigated. Electroplasmolysis and microwave applications were optimized by response surface methodology. Optimum conditions were these: voltage gradient of 22.2 V/cm and treatment time of 60 s for electroplasmolysis, and flow rate of 90 mL/min with power of 900 W for microwave heating. Production of carrot juice was carried out by using these optimum conditions. After production, carrot juice samples were stored for 4 mo at +4 °C and analyses were performed at monthly intervals. As a result of electroplasmolysis, a 9.7% increase in juice yield was obtained. In addition, 100% pectin methylesterase inactivation was found with the microwave heating application. The results showed that the highest values for quality characteristics, such as antioxidant capacity and total pectin, total phenolic, and total carotenoid contents, were obtained with the combined applications of the electrical methods. In addition, these quality characteristics were protected better in the group of combined applications of the electrical methods (electroplasmolysis + microwave) during storage.

Dielectrical properties of food materials--1: factors affecting and industrial uses.

The electrical properties of foods and biological products have been the most valuable factors in the novel food technology. They have been defined both from electromagnetic field concepts and from the electrical-circuit point of view. Recently, these properties are used to assess the characterization of the processes based on electrical methods: electromagnetic, electro-processes. This article is a review of dielectrical properties of food materials. It also includes factors affecting the dielectrical properties of foods and their industrial uses.

Dielectrical properties of food materials--2: measurement techniques.

The knowledge of the electrical properties of the materials to be processed or measured is important in the design of the equipment. Dielectric properties determine the behavior of the materials, when subjected to high frequency or microwave fields in dielectric heating processes or cooking. This article is a review of the measurement techniques of the dielectrical properties of food materials. This study also includes the classification of electrical properties and their importance in food processing.

Decontamination techniques of pathogen bacteria in meat and poultry.

Means of controlling or even improving the safety of food products is to decontaminate the carcasses or products during or at the end of the production line. The decontamination of meat and poultry can help to reduce human foodborne infections. However, process hygiene to prevent contamination should never be neglected. Some techniques of decontaminating raw meat and poultry meat products are discussed in this review.

Effects of drying process on antioxidant activity of purple carrots.

Purple carrot was analysed for its antioxidant activity by measuring its scavenging effect on 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical. The amount of purple carrot necessary to decrease by 50% the initial DPPH concentration (EC50) was found 30.23 +/- 5.17 (mg sample/mg DPPH). Effects of the dehydration process on the antioxidant activity of purple carrots were also determined after dehydration by using tray drier and microwave+tray drier combination. Purple carrots were cleaned, washed, sorted, sliced, and blanched in water at 98 +/- 1 degree C for 2 min. Then half of the samples were dehydrated in microwave (45 min) and tray drier (105 min) combination, and others were dehydrated in tray drier (150 min) until reaching the constant weight. Raw, blanched and dehydrated purple carrots were compared for their antioxidant activity and total anthocyanin contents, color values (L*, a*, b*, C*, H degrees) and dry matter contents. The antioxidant activity as measured by DPPH, EC50 value ranged from 7.80 to 30.23 of processed and raw carrots where the H degrees values were changed from -3.68 to -23.96 corresponding to a bluish hue.