Development, testing and optimization of production technology for preparation of millet based, soy fortified, flavoured ready to eat extruded sweet snacks
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Date
2016
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JNKVV
Abstract
Abstract:
Food extrusion is a technology that is extensively used for the development of new products using starch-based raw materials. In present study extrudates were prepared to identify the optimum machine parameters and prepare good quality ready-to-eat extruded snacks from a suitable blend of Kodo millet flour (KMF), defatted soy flour (DSF) and water chestnut flour (WCF). Millet is ancient grain, with its mildly sweet flavour, is tasty, soothing, non-acid forming and contains a myriad of beneficial nutrients. This readily available food is easily digestible. The other component DSF is known for its rich and high amount of protein. As flvouring components the starch available from water chestnut, a local annual aquatic crop of Mahakoshal region of MP will be blended in appropriate proportions.
With this idea in mind, the present study is under taken: to optimize process parameters for protein enrichment of Kodo based snack food; to conduct physical, textural and biochemical properties of extrudates and to study the break even analysis and benefit-cost ratio of process. The moisture content of flour at different blend ratio was then measured by standard hot air oven drying method. After getting the moisture content of KMF, DSF and WCF blends, additional water required to raise the moisture content to desired levels of blends i.e. 8, 10, 12, 14 and 16% (wb) was calculated. Then calculated amount of water plus an additional 10% of calculated water was added to supplement the evaporation losses during mixing and conditioning. Tempering of samples was done by keeping the
moistened smaples for 24 h at room temperature (250C) so as to get uniform
distribution of moisture throughout the mass of blends. The conditioned sample was then feed to the Brabender single screw extruder under pre set operational conditions. The product after coming out of the extruder discharge end through round die, expanded due to sudden release of pressure. The extrudates were collected and packed in laminated polythene bags and properly labelled for further analysis.
Data analysis was done for optimization of operational and processing parameters of extrudates physical properties i.e. moisture content of extrudates (MCE), mass flow rate (MFR), sectional expansion index (SEI),
water absorption index(WAI), volumetric expansion index(VEI), specific length (SL), bulk density (BD) and true density (TD) of extrudates; biochemical properties (i.e. protein, carbohydrate, fat and ash content); textural properties (hardness and crispness) and colour value (L*, a* & b*) of extrudates prepared out of KMF-DSF-WCF blends using software Design-Expert 9.0.0 (45 days trial pack). Response surface graphs and contour plots were drawn with the help of Design-Expert 9.0.0 to know the effect of independent variables on the responses. Texture test of extrudates was made using Texture Analyzer System (model: TAXT2i). The data were analyzed separately using second order mathematical model. Adequacy of the model was tested using coefficient of determination and Fisher’s F-test and the effect of variables were interpreted. Response surface graphs were drawn to illustrate the effects of variables on the different pair of responses.
MCE increased and the rate of increment is almost uniform with increase in MCF. Also the MCE decreased with increase in the proportion of defatted soy flour in blend. MCF played key role in variation of MFR of extrudates. The elevation of contours increased towards the higher value of MCF, which means as the value of moisture content increased the MFR also increased simultaneously.
The SEI decreased sharply with increasing MCF. It can be seen that when the WCF content is high, low value of WAI is probably due to the sucrose content of chestnuts. Sucrose, in fact, as well known, has a restrictive effect on gelatinization process. The VEI decreased sharply with increasing MCF. Also as it is seen the increase in amount of WCF increases the VEI because increase in water chestnut flour reduces DSF which has high value protein content which reduces the VEI.
The MCF had vital role over SL of extrudates, when the value of moisture content increased the SL also increased simultaneously. It can be seen when BT and DHT increases the BD decreases. Extrudates density is inversely related to overall expansion. The TD increased with increase in MCF. It can be seen that extrusion temperature is inversely proportional to TD of extrudates, with increase in BT and DHT, the TD decreases.
The protein content of extrudates increased with increase in percentage of DSF in the blend as it contains highest percentage of protein.
The increase in BT the amount of carbohydrate content increased. The fat content of extrudates increased with increase in BT. Change in SS does not affect the fat content. Ash content of extrudates is increased when increase the portion of DSF.
The hardness increased with increase in MCF as an indicative of creation of less porous structure of extrudates leading to increased hardness. It is observed that crispness increases with decrease in MCF of feed as an indicative of creation of more porous structure of extrudates leading to increased crispness. The lightness parameter (L*) of extrudates decreased with increasing BT and increased with increasing MCF. The redness (a*) increased with increasing BT and DHT and decreased with increasing MCF. The change in yellowness (b*) increased with increasing DHT.
The optimum process and machine parameters characterized for most acceptable extrudates of KMF-WCF-DSF blends are identified as MCF of 12%, BR 70:15:15, DHT 2000C, BT 1200C and SS 160 rpm. The cost analysis of extrudates by a commercial extruder (with production capacity of
1500000 packets per month of 20 grams) of ready to eat extruded snacks of blended flour consisting of blend of KMF: DSF: WCF in the proportion of
70:15:15 indicates the break even quantity of 27, 61,506 units, the break even sales of Rs. 1, 65, 69,036=00 and break even period of 448 days. Thus the unit can be economically viable if the product can be sold @ Rs. 6/- per unit of
20 g. The result of benefit cost ratio is showed that every one rupee invested is expected to earn 12.41 rupees.
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POST HARVEST PROCESS AND FOOD ENGINEERING