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Received: 4 March 2014
Received in revised form: 21 January 2014
Accepted: 27 January 2014
Keywords
Banana pulp
Clarified juice
Enzymatic clarification
Response surface methodology
Abstract
The study was initiated to optimize the enzymatic clarification process of banana pulp of maturity stage 6 using response surface methodology. Banana pulp was treated with pectinase enzyme (Pectinex Ultra SP-L) at various concentrations (0.05-0.15%), incubation temperature (30-50oC) and time (60-180 min) of treatment. The effect of these enzymatic conditions on per cent juice yield, viscosity of banana pulp and clarity of banana juice were studied by employing Central Composite Design. Significant regression model describing the changes of juice yield, viscosity and clarity of juice with respect to hydrolysis parameters were established with the coefficient of determination, R2 = 0.9851, 0.9883 and 0.9679, respectively. Based on response surface and desirability graph, the optimum conditions for clarification of banana pulp were: 0.12% enzyme concentration, 38.84oC incubation temperature and 136.52 min of incubation time resulted juice yield, viscosity of pulp and clarity of juice under above conditions were 64.76%, 450.20 cps and 84.56%, respectively.
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Introduction
Generally, fruit juices are extracted by simple crushing and or grinding of fruits. However, in case of banana this process results in a sticky, lumpy mass with no juice. Bananas are usually too pulpy and pectinaceous to yield juice by simple pressing or centrifugation (Adao and Gloria, 2005). Of the problems associated with banana pulp processing, a high viscosity seems to be the most severe. The turbidity and viscosity of banana juice are caused mainly by the polysaccharides in the juice such as pectin and starch (Lee et al., 2006). Pectin makes the clarification process harder because of its fibre-like molecular structure. Starch is also a common problem for juice processors. Polymeric carbohydrates like starch may make filtration difficult and cause post-process cloudiness.
Application of enzymes such as pectinase and amylase improved the clarification process for banana fruit juices (Koffi et al., 1991; Yusof and Ibrahim, 1994; Lee et al., 2006). Pectinase hydrolyzes pectin and causes pectin-protein complexes to flocculate. The resulting juice has a much lower amount of pectin and a lower viscosity, so any subsequent clarification process is shortened. The enzymatic clarification is influenced by a number...