Drying Kinetics of Fresh and Osmotically Pre-treated Star Fruit ((Averrhoa carambola L.) slices.
Research Type
Departmental Research
Experiment Background
Star fruit (Averrhoa carambola, L.) originates from Southeast Asia. The fruit is 5 -15 cm in length and is ovate to ellipsoid in shape, usually with five prominent longitudinal ribs; star shape in cross section. The skin is thin, smooth and waxy, and turns a light to dark yellow when ripe. The entire fruit is edible, including the slightly waxy skin. The flesh is translucent, crisp, extremely juicy and without fibers. For optimum sugar content, fruits with yellow to golden yellow colour (all trace of green disappear from fruit surface) should be selected for drying. Currently most of the star-fruit is commercialized as fresh fruit, although there is a considerable interest in commercializing it as pre-cut or sliced fruit, mainly due to its star shape, much used in decorating dishes. It is a source of many nutrients, but its fragility and high moisture content facilitate its deterioration, resulting in a limited shelf life. Oxalic acid has been identified as principal acid in star fruit whose high concentration may decrease the dietary calcium by forming a poorly absorbed calcium oxalate-complex. To avoid it to an extent, ripen sweet star fruit (Oxalic acid 0.22-0.97 mg/g of wet weight) are chosen in this study.
Sensorial quality of the dried fruits can be improved by osmotic dehydration prior to hot-air drying. Osmotic dehydration (OD) of fruits is usually carried out by immersion of pieces of these in a hypertonic solution containing one or more solutes. The different osmotic pressure between fruit and solution promotes the simultaneous flow of water and solutes, both of the solutes from the solution to the fruit and of water and other solutes from the fruit to the solution. So, the present study shall be undertaken with the following objectives:
Experiment Group
Agricultural Engineering
Unit Type
(02)EDUCATION UNIT
Unit
(13)ASPEE COLLEGE OF HORTICULTURE (NAVSARI)
Department
(218)Post Harvest Technology,ACHF, Navsari
BudgetHead
(329/12935/00)329/01/REG/00285
Objective
1. To optimize the osmotic pre-treatment process of star fruit slices prior to hot- air-drying.
2. To study the influence of pre-treatment and hot-air-drying temperature on drying kinetics and sensory quality of dehydrated star fruit.
3. Cost of economics
Season
Annual
Location Unit Type
(02)EDUCATION UNIT
Location Unit
(13)ASPEE COLLEGE OF HORTICULTURE (NAVSARI)
Location Department
(218)Post Harvest Technology,ACHF, Navsari
Plot No
-
PI Name
(NAU-EMP-2013-000924)FAKIR MOHAN SAHU
PI Email
fmsphtc@nau.in
PI Mobile
9879123286
Year of Approval
2014
Commencement Year
2015
Completion Year
2024
Design of Experiment (Other)
Pre-treatments:
Osmotic solution concentrations: 40oB, 50oB and 60oB (Sucrose solution)
Osmotic solution temperature: 30 oC, 40oC and 50oC
Immersion time: 120 min., 180 min and 240 min
The Response Surface Methodology (Box-Behnken Design) of three variables and three level each with three-centre point combination is used. This design is taken because it fulfills most of the requirement for optimising the pretreatment (osmotic dehydration) process prior to convective drying.
Table 1. Experimental design for three factor- three level response surface methodology