Optimisation of low temperature extraction of banana juice using commercial pectinase Sorel Tchewonpi Sagu a , Emmanuel Jong Nso a , Sankha Karmakar b , Sirshendu De b,⇑ a Department of Process Engineering, National School of Agro-Industrial Sciences (ENSAI), University of Ngaoundere, P.O. Box 455, Adamaoua, Cameroon b Department of Chemical Engineering, Indian Institute of Technology, Kharagpur, Kharagpur 721 302, India article info Article history: Received 29 July 2013 Received in revised form 31 October 2013 Accepted 6 November 2013 Available online 16 November 2013 Keywords: Banana juice Extraction Enzymatic treatment Optimization Response surface methodology abstract The objective of this work was to develop a process with optimum conditions for banana juice. The procedure involves hydrolyzing the banana pulp by commercial pectinase followed by cloth filtration. Response surface methodology with Doehlert design was utilised to optimize the process parameters. The temperature of incubation (30–60 °C), time of reaction (20–120 min) and concentration of pectinase (0.01–0.05% v/w) were the independent variables and viscosity, clarity, alcohol insoluble solids (AIS), total polyphenol and protein concentration were the responses. Total soluble sugar, pH, conductivity, calcium, sodium and potassium concentration in the juice were also evaluated. The results showed reduc- tion of AIS and viscosity with reaction time and pectinase concentration and reduction of polyphenol and protein concentration with temperature. Using numerical optimization, the optimum conditions for the enzymatic extraction of banana juice were estimated. Depectinization kinetics was also studied at optimum temperature and variation of kinetic constants with enzyme dose was evaluated. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction Banana, mango, guava, and pineapple are major fruits planted widely in tropical and subtropical regions of Africa, Asia and South America. Banana has a high nutrition value and is a good source of energy due to its high level of starch and sugar. It is also a source of vitamins A and C, potassium, calcium, sodium and magnesium (Fabiano, Sueli, Odisse, Gaspareto, & Edson, 2006). Banana is highly appreciated due to its aroma and flavour. It is consumed mainly as fresh fruit and only a small quantity is stored. Banana is very susceptible to deterioration due to rapid decomposition when rip- ened, and techniques of cold storage are not quite suitable. Consid- erable amount of this fruit is wasted due to inadequate processing and preservation techniques (Maskan, 2000). For valorisation of this product, the common processed banana products manufac- tured are banana puree, banana figs, banana powder or flour, bana- na chips, canned banana slices, banana jam and banana vinegar (Tsen & King, 2002). Studies were carried out to remove water. For this, previous works focused predominantly on drying banana. Mowlah, Takano, Kamoi, and Obara (1983), Mulet, Berna, and Rossello (1989) and Wang and Chen (1998) worked on modelling of the drying kinetics of banana. Minh-Hue and Price (2007) worked on influence of experimental parameters like slab thick- ness, banana maturity and harvesting season on air-drying of banana. Fabiano et al. (2006) optimised osmotic dehydration of ba- nana followed by air-drying. Several works also focused on banana puree (Tsen & King, 2002). Bananas are also suitable for juice production but the process- ing of the banana after harvesting is a major challenge (Mohapatra, Mishra, Singh, & Jayas, 2011). One of the biggest problems is the pectinaceous nature of the banana fruit that makes juice extraction difficult. Gensi, Kyamuhangire, and Carasco (1994) accomplished extraction of banana juice from ripe peeled or unpeeled bananas by a traditional method of mashing with hands in plastic basins using Imperata cylindrica grass as a processing aid. This study was conducted to elucidate traditional methods to produce banana juice in Uganda. Byarugaba-Bazirake (2008) applied commercial enzymes (Rapidase CB, Rapidase TF, Rapidase X-press and OE-Lall- zyme) in the processing of banana juice for wine production. The objective was to vary enzyme concentration at different range and observe the parameters influencing wine processes. Dha- msaniya and Varshney (2013) developed a process to evaluate whey beverage with ripe banana juice. Banana slices along with water in the ratio of 1:2 (banana slice:water, w/w) were heated at 100 °C for 45 min followed by the cooling, pressing, centrifuging, filtration, pasteurization (at 90 °C for 10 min) and again cooling at room temperature and no enzyme was used. Besides that, some works have led to the optimization of operating conditions of ba- nana juice extraction. A three-level rotatable design was used by Shahadan and Abdullah (1995) to determine optimum conditions for the extraction of banana juice. The effects of temperature 0308-8146/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.foodchem.2013.11.031 ⇑ Corresponding author. Tel.: +91 3222 283926; fax: +91 3222 255303. E-mail address: sde@che.iitkgp.ernet.in (S. De). Food Chemistry 151 (2014) 182–190 Contents lists available at ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem