Extraction and characterization of fibre from by-products of carrot, kinnow and pea for their utilization in food
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Date
2018
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Punjab Agricultural University, Ludhiana
Abstract
The present investigation was undertaken to extract and characterize dietary fibre from carrot pomace, pea pod, kinnow peel and pomace. Three independent variables viz. temperature (30-90oC), time (5-15min) and s: w ratio (1:5-1:10) were selected using experimental design of software design expert and 13 different combination were formed for preparation of fibre concentrate. Optimization of fibre extraction was done using Box-Behnken design Response surface methodology. Temperature had significant effect on the total dietary fibre (TDF), ferric reducimg ability of plasma (FRAP), water holding capacity (WHC) and oil holding capacity (OHC) of fibre concentrate from carrot pomace, pea pod, kinnow peel and pomace except on the WHC of kinnow peel. Time had significant effect on TDF, FRAP, WHC and OHC of carrot pomace, pea pod and kinnow pomace fibre concentrate. However, in kinnow peel significant effect of time was observed only on FRAP activity of fibre concentrate. Sample: water (s:w) ratio had significant effect only on FRAP activity of pea pod, kinnow peel and pomace and WHC of kinnow pomace fibre concentrate. The optimum process parameters for fibre concentrate preparation from carrot pomace were: temperature 90o C, time 15 min and s:w ratio 1: 8.94 under which 73.56% TDF, 21.97 mg/g FRAP, 7.89 g/g WHC and 2.50 g/g OHC was found. The optimum process parameters for pea pod were: temperature 47.23o C, time 15 min and s:w ratio 1:9.37, under which 51.55% TDF, 25.98 mg/g FRAP, 6.25 g/g WHC and 2.00 g/g OHC was found. The optimum process parameters for kinnow peel and pomace were: temperature 73.98 and 60.52oC, time 5 and 8.33min and s:w ratio 1:5 under which 68.74 and 65.17% TDF, 42.45 and 21.55 mg/g FRAP, 7.80 and 7.01 g/g WHC and 5.88 and 3.53 g/g OHC was found. The fibre concentrate prepared under optimum conditions were dried by different methods (lyophilizer, microwave and oven drying). Methods of drying had no significant effect on TDF, crude protein, fat and functional properties, whereas, phenolic content and antioxidative activity were affected by drying. Carrot pomace fibre concentrate had highest TDF content whereas, antioxidative activity and phenolics was found highest in kinnow peel. Highest SDF/IDF ratio (1:3.75-1:4.52) was found for kinnow pomace and lowest value (1:1.95-1:2.81) for kinnow peel fibre concentrate. Maximum WHC and SWC were observed in carrot pomace and maximum OHC was in kinnow peel fibre concentrate. Packaging of fibre concentrate in AF, LDPE and PP bags and storage for 6 months under ambient and refrigerated conditions did not show any significant effect on TDF and functional properties of fibre concentrate. However, phenolic content and FRAP activity decreased during storage. Cookies at 5% replacement of refined wheat flour with carrot pomace fibre concentrate were most accebtable than other levels of replacement as well as replacement with other fibre concentrates. In conclusion, fibre concentrates from the by-products are good sources of dietary fibre with optimum SDF/IDF ratio and can be used in formulation of functional foods.
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