Osmotic dehydration of pineapple slices pre-treated by electroplasmolysis: Determination of color change kinetics

The pineapple (Ananas comosus (L.) Merrill) is a commercial tropical fruit belonging to the Bromeliaceae family. It is rich in organic acids (citric acid, malic acid), minerals (Fe, Mg, Ca, P, K, and Zn), and vitamins (A, B1, B2, B3, and B6). Osmotic dehydration is a water removal technique by immersing the fruit in a hypertonic solution to obtain minimally processed food with a longer shelf life and high nutritional value. It can also be considered as a pretreatment that reduces the required energy inputs for convective drying and freeze-drying. Electroplasmolysis is an electrical method that is based on the growth of pores in cell membranes. It has an important effect on the dehydration and extraction processes as it increases the cell permeability and mass transfer coefficients of plant tissues. In this study, it was aimed to determine the effect of electroplasmolysis pretreatment on color change kinetics in the osmotic dehydration of pineapple slices. Electroplasmolysis was applied by a drum‐type electroplasmolyzator with 80 V/cm voltage gradient for 60 s. The osmotic dehydration process was carried out with sucrose solutions of 40, 50 and 60 ◦Bx at 20 ◦C. The processing time was 6 h in all osmotic treatments. This time was determined in preliminary experiments. Osmotically dehydrated samples with elelctroplasmolysis pretreatment and the samples without electroplasmolysis application were compared via L, a, and b values during 8 hours. The results of the study showed that fresh pineapple samples had higher L, a, and b values than both electroplasmolysis treated and untreated samples. The color values of all the samples, with and without electroplasmolysis pretreatment, decreased parallel to time increase after the osmotic dehydration process. L, a, and b values of the samples which osmotically dehydrated at 60 ◦Bx solution were higher than the color values of the samples which were dehydrated at 40 and 50 ◦Bx solutions. Lightness and yellowness were found higher in the electroplasmolysis group than the other groups. The zero-order and first-order kinetic models were used to explain the color change kinetics and it was observed that L, a, and b were fitted to a first-order kinetic model

FARKLI KARBONHİDRAT FORMÜLASYONLARI İLE ÜRETİLMİŞ AYVA SUYU KONSANTRESİ KATKILI SERT ŞEKERLERİN KALİTE ÖZELLİKLERİNİN İNCELENMESİ

Bu çalışmada farklı karbonhidrat formülasyonları kullanılarak ayva suyu konsantresi katkılı sert şeker üretimiamaçlanmıştır. Her bir karbonhidrat formülasyonu (%100 sakkaroz, %75 sakkaroz+%25 glikoz, %75sakkaroz+%25 fruktoz) için geleneksel açık kazan üretim yöntemi kullanılarak sert şeker üretilmiştir.Ürünlerin renk, camsı geçiş sıcaklığı (Tg) ve higroskopisite değerleri, şeker kompozisyonları, duyusalözellikleri incelenmiştir. % 100 sakkaroz kullanılarak üretilen sert şekerlerin L*, a* ve b* değerleri en yüksekolarak bulunmuştur. Şeker formülasyonlarına glikoz ve fruktoz ilavesi ürünlerin Tg değerinde azalmaya nedenolmuştur. %75 sakkaroz+ %25 fruktoz formülasyonu kullanılarak üretilen sert şekerlerin higroskopisitedeğeri en yüksek olarak bulunmuştur. Karbonhidrat formülasyonundaki farklılık ürünlerin şekerkompozisyonunu etkilemiştir. Formülasyonunda glikoz içeren sert şekerler genel beğeni kriteri açısından enyüksek puanlanmıştır

INFLUENCE OF ULTRASONIC AND ELECTRICAL PRETREATMENTS ON THE DRYING AND QUALITY CHARACTERISTICS OF KIWI FRUIT SLICES

In this study, the drying characteristics and quality properties of electrical (ET) and ultrasound (US) pre- treated kiwi fruit slices were investigated. Electrical and ultrasound pretreatments were carried out on the parameters of 100 V- 40 sec. and 35 kHz-30 min respectively. After the pretreatments, the kiwi fruit slices were dehydrated using a convective dryer at 50°C and 1.5 m/s air flow rate. The effects of these pretreatments on the drying rate and quality properties (the total phenolic content, vitamin C, pectin contents, rehydration rate, acidity, and color values) were evaluated. Consequently, the US and ET pretreatments provided an increase in the drying rate by 18.34% and 21.65% respectively. The combination of pretreatments (ET+US) increased the drying rate by 35.70%. The ET pretreatment produced minimum changes in the samples' pectin content and color values, and the US application increased the vitamin C, rehydration capacity, and acidity

KARA HAVUÇ SUYU ÜRETİMİNDE ELEKTROPLAZMOLİZ ve MİKRODALGA UYGULAMALARININ VERİM ve KALİTE ÖZELLİKLERİ ÜZERİNE ETKİLERİ

Electrical methods which are among the new processing methods were used in this research. the effects of electroplasmolysis as a pretreatment on yield and quality and the effects of microwave heating as an alternative to traditional heating on the quality of black carrot juice were investigated. Production of black carrot juices was made at 22.22 V/cm-60 sec for electroplasmolysis applications and 90 mL/min flow rate (total heating time 2 min), 900 W (power) for microwave heating. Production of black carrot juice was carried out by using these conditions for each treatment. As a result of electroplasmolysis more than 4.4% increase in yield was determined. in addition, 100% PME inactivation was found for microwave heating application in a shorter time compared to traditional pasteurization (P;#8804;0.05). the results showed that the highest quality values like pectin, phenolic, anthocyanin contents and antioxidant capacity were determined on combined applications of electroplasmolysis and microwave heating.Güncel gıda işleme yöntemlerinden olan elektriksel işlemlerin kullanıldığı bu çalışmada verim artışı sağlamak amacıyla ön işlem olarak uygulanan elektroplazmoliz ile geleneksel ısıtma yöntemine alternatif olarak uygulanan mikrodalga ısıtma tekniklerinin kara havuç suyu kalitesi üzerine etkileri incelenmiştir. Kara havuç suyu üretiminde uygulanan elektroplazmoliz işlemi 22.22 V/cm’de 60 sn ve mikrodalga ısıtma uygulaması 90 mL/dak akış hızı (kalış süresi 2 dak), 900 W güç düzeyinde uygulanmış ve bu koşullar kullanılarak kara havuç suyu üretimleri gerçekleştirilmiştir. Elektroplazmoliz uygulaması ile %4.4 verim artışı; mikrodalga ısıtma uygulaması ile geleneksel pastörizasyona göre daha kısa sürede %100 PME inaktivasyonu sağlanmıştır (P?0.05). Elektroplazmoliz ve mikrodalga kombinasyonu ile üretilen kara havuç sularının pektin, toplam fenolik madde, antosiyanin içeriği ve antioksidan kapasite gibi kalite özellikleri açısından geleneksel üretim yöntemine kıyasla üstün oldukları saptanmıştır