EFFECT OF PROCESSING ON THE DIETARY FIBRE COMPOSITION OF TRADITIONAL BREAKFASTS

Abstract

Dielary fibre is defined as “ remnants of edible plant cell walls, polysaccharides, lignin and associated substances resistant to hydrolysis (digestion) by alimentary enzymes of humans.It includes macro constituents of plant foods e,g. Cellulose, hemiccllulose, pectins and other substances such as lignin, gums, mucilages, waxes and suberin.

The physical properties of dietary fibre show physiological effects in human systems. From the technological aspects, dietary fibre shows functional properties. The physiological role of dietary fibre is demonstrated in analytical methods as insoluble dietary fibre (ID F ) and soluble dietary fibre (SDF) fractions.

The objectives of this study were, a) to determine total dietary fibre (ID F & SDF) of breakfast preparations, b) to study the effect of processing on the dietary fibre fractions (Insoluble & Soluble) of breakfast: preparation and c) to compare the dietary fibre fractions of traditionally prepared and commercially available breakfast preparations.

Rice flour, wheat flour, black gram and semolina were used as raw materials. In the processing these raw materials, dry milling, wet-milling, roasting, fermentation, steaming techniques were used, depending on the type of breakfast preparations. The commercial preparations included two types of bread ( 100% wheat flour and 85%: 15% o f wheat Hour: Kurmkan). The results showed that the highest contribution of dietary fibre was from breakfast preparations containing rice flour (8.7%). Wheal flour bread contributed the least as dietary fibre ( 1.8%), This could be attributed to the high extraction rate (72%) o f milling of the wheat flour.

Of the two milling processes o f rice flour, ‘wet milling + roasting" contained a higher SDF% and IDF % The total dietary fibre (TDF) content of string hoppers made with wet untied floor and dry milled flour were 9.7% and 8.8% , respectively. Steaming or the extruded flour increased the T D F in the string hopper preparation by

approximately 13 % . Similar observations were made with the wheat flour where the increase in the soluble fibre accounted to over 20.4%. This can be attributed to the formation of resistant starch, which is precipitated in the dietary fibre analysis. Today resistant starch, which has the property to ferment in the gut, is also considered as dietary fibre. Black gram contains a. high dietary fibre as a raw ingredient but in the preparation of idly, it contributes moderately to the dietary fibre (4.25%) intake. Idly is formulated using semolina and black gram in the ratio of 2:1. In preparation of idly, removal of seed hull from the black gram after soaking, reduced its dietary fibre content. In bread, substitution of wheat flour with 15% Kurakkan increased the total dietary fibre to 3.2%. (IDF: 2.85% and SDP:0.33%). The study concludes that processing of foods increase the dietary fibre content of breakfast preparations during steaming and roasting, which can be attributed to the formation of resistant starch. The contribution of dietary fibre from commercially available breakfast preparations (e.g.bread) is less than that of the traditionally prepared breakfasts (idly, string hoppers). Rice based breakfast preparations (eg. 180 g) contribute approximately 56% of the fibre requirement to the daily diet.