Technology optimization for preparation of banana juice by combining composite enzymatic hydrolysis with high hydrostatic pressure

Abstract: Dajiao is an excellent potential raw material for industrial banana procession. Musa ABB group Dongguang dajiao was used as raw material to prepare banana juice. In order to increase yield and improve the quality of banana juice, composite enzymatic hydrolysis (Unikpectinase FM, containing cellulase, pectinase, glucanase, xylanase) and high hydrostatic pressure (HHP) processing with highly effective bactericidal effect were introduced in the preparation of Dajiao juice. The combined technique can keep the original flavor, color and nutritional components. Moreover it showed low energy consumption and non-pollution to the environment. Firstly, the optimal enzymatic hydrolysis conditions were obtained by orthogonal design with the juice rate as the index, every measuring datum was repeated 3 times and an average was applied. Secondly, banana juice prepared by the optimal enzymatic hydrolysis conditions was processed by HHP, respectively in 0.1 (untreated control group), 150, 300 and 450 MPa for 10 min. The effects of different pressure treatments on the colour, browning degree and colony count of banana juice were studied. According to the results of orthogonal experiment and considering the demand of practical production, the optimum conditions of enzymatic hydrolysis were as follows: the enzyme amount 0.025%, time 1.5h, temperature 35℃, pH value 4, and the juice yield under these optimum conditions was 81.6%. HHP had a very good protective effect on the color of Dajiao juice. The bactericidal effect was improved with the increase of the pressure level. After the treatment of HHP at 450 MPa for 10 min, the count of total bacteria was decreased to 10 cfu/mL by 90.25%. The aroma components in banana juice before and after HHP treatment were analyzed by combining solid phase micro extraction (SPME) with gas chromatography mass spectrometry (GC-MS) method, investigating the changes of the aroma components. The data were subjected to analysis of variance using the SPSS1.7.3. Statistical significance was defined as p<0.05. After HHP treatment, the aldehydes content was decreased significantly and the alkenes content was increased significantly in banana juice. HHP treatment induced little on the overall aroma perception of banana juice. This study provides a new way for deep-processing of banana.