Taner Baysal

The Use of Ultrasound and Combined Technologies in Food Preservation

Ultrasound techniques find use in the food industry in both the analysis and modification of foods. Microbial and enzyme inactivation are other applications of ultrasound in food processing. The use of ultrasound on its own in the food industry for bacterial destruction is currently unfeasible; however, the combination of ultrasound and pressure and/or heat shows considerable promise. The future of ultrasound in the food industry for bactericidal purposes lie in thermosonication, manosonication, and manothermosonication, as they are more energy-efficient and result in the reduction of microbial and enzyme activity when compared to conventional heat treatment. The use of ultrasound and combined technologies, mechanisms, and effects of ultrasound combinations are discussed in this review.

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.

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.

Color and Lycopene Content of Tomato Puree Affected by Electroplasmolysis

Tomato puree was produced using three different breaking methods, namely heating by steam injection, by electroplasmolysis, and combination of both steam injection and electroplasmolysis. In electroplasmolysis, the tomato pulp was treated at the electric field strength of 68 V/cm for 1.5 seconds. L, a, b, a/b, tomato color index, total color difference, chroma difference, hue angle, and lycopene content of purees were measured. Puree samples breaked by electroplasmolysis had better color values and the highest lycopene content. The a/b, tomato color index, and lycopene content of these samples were as 2.00; 49.94 and 273.9 mg/kg, respectively.

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.

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.

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.

KIRMIZI BİBER PÜRESİNİN VERİM VE KALİTESİNE MİKRODALGA ISITMANIN ETKİSİ

Bu calismada kirmizi biber puresinin verim ve kalitesi uzerine konvansiyonel isitma teknigine alternatif olarak mikrodalga isitma teknigi uygulanmistir. Mikrodalga isitma uygulamasi verim ve cikis sicakligi cevap olacak sekilde yanit yuzey metodu ile optimize edilmistir. Mikrodalga isitma uygulamasinin yanit yuzey metodu ile optimum kosullari 900 W guc ve 6.52 rpm akis hizi olarak saptanmistir. Bu optimum calisma kosullarinda verim ve cikis sicakligi %76.76 ve 95 °C olarak bulunmustur. Konvansiyonel isitma uygulamasi da mikrodalga isitmada ulasilan ayni sicaklik derecesinde 95°C ve 9 dk olarak yurutulmustur. Sonuc olarak mikrodalga isitma uygulamasi ile verimde %8.07, pektin iceriginde %17.75, C vitamin iceriginde %20.6 artis saptanmistir.Bu calismada kirmizi biber puresinin verim ve kalitesi uzerine konvansiyonel isitma teknigine alternatif olarak mikrodalga isitma teknigi uygulanmistir. Mikrodalga isitma uygulamasi verim ve cikis sicakligi cevap olacak sekilde yanit yuzey metodu ile optimize edilmistir. Mikrodalga isitma uygulamasinin yanit yuzey metodu ile optimum kosullari 900 W guc ve 6.52 rpm akis hizi olarak saptanmistir. Bu optimum calisma kosullarinda verim ve cikis sicakligi %76.76 ve 95 °C olarak bulunmustur. Konvansiyonel isitma uygulamasi da mikrodalga isitmada ulasilan ayni sicaklik derecesinde 95°C ve 9 dk olarak yurutulmustur. Sonuc olarak mikrodalga isitma uygulamasi ile verimde %8.07, pektin iceriginde %17.75, C vitamin iceriginde %20.6 artis saptanmistir.