Influence of pre-treatment on yield and quality of mandarin juices

Croatia in the Neretva valley produces remarkable quantities of mandarins but, as always, one part of yield, according to fruit characteristics, are not suitable for consumption as fresh. At the same time those fruit are suitable for processing industry e.g. for juice production. In Croatia, mandarin juice is not industrially produced, and generally is rare on market. The current study is contribution to mandarin juice processing with the aim to investigate influence of different pre-treatment on yield, quality, biological and sensorial attributes of obtained juices. Mandarin from Neretva valley was used to produce cloudy juices on small scale equipment. Before pressing, fruits were peeled and treated (i) with maceration enzymes at various temperature and duration (EPT) (ii) by ultrasound (USPT) with different amplitude and duration. Control juices were produced without enzymes or USPT. In juices biologically active compounds (BAS) total carotenoids (TC), total phenolics (TP), and vitamin C were determined. All juices were sensory evaluated (SE) by quantitative descriptive method. The results were statistically analyzed. Considering the investigated parameters there are no remarkable differences among juices produced by enzyme treatments independent of enzyme concentration, temperature (20 or 50 oC) and duration of 30 or 60 min. regarding to BAS and SE. Also, different US treatment conditions did not show any remarkable influence on investigated parameters. But in comparison of these two types of treatment better yield and SE were obtained by US and higher content of TC was obtained by enzyme treatment. Treatment by US could be recommended to produce mandarin juice due to high yield and SE but also further investigations are needed to optimize US conditions due to better preservation of BAS.