PREPARATION OF CLEAR NOODLES WITH MIXTURES OF TAPIOCA AND HIGH-AMYLOSE STARCHES

Ways to simulate the making of clear noodles from mung bran starch wer e investigated by studying the molecular structures of mung bean and t apioca starches. Scanning electron micrographs showed that tapioca sta rch granules were smaller than those of mung bean starch. X-ray diffra ction patterns of mung bean and tapioca starch were A- and C-A-pattern s, respectively. Iodine affinity studies indicated that mung bean star ch contained 37% of apparent amylose and tapioca starch contained 24%. Gel permeation chromatograms showed that mung bean amylopectin had lo nger peak chain-length of long-branch chains (DP 40) than that of tapi oca starch (DP 35) but shorter peak chain-length of short-branch chain s (DP 16) than that of tapioca starch (DP 21). P-31 n.m.r, spectroscop y showed that both starches contained phosphate monoesters, but only m ung bean starch contained phospholipids. Physical properties, includin g pasting viscosity, gel strength, and thermal properties (gelatinizat ion), were determined. The results of the molecular structure study an d physical properties were used to develop acceptable products using m ixtures of cross-linked tapioca and high-amylose maize starches. Tapio ca starch was cross-linked by sodium trimetaphosphate (STMP) with vari ous reaction times, pH values, and temperatures. The correlation betwe en those parameters and the pasting viscosity were studied using a vis co/amylograph. Starches, cross-linked with 0.1% STMP, pH 11.0, 3.5 h r eaction time at 25, 35, and 45 degrees C (reaction temperature), were used for making noodles. High-amylose maize starch (70% amylose) was m ixed at varying ratios (9, 13, 17, 28, 37, and 44%) with the cross-lin ked tapioca starches. Analysis of the noodles included: tensile streng th, water absorption, and soluble loss. Noodle sensory properties were evaluated using trained panelists. Noodles made from a mixture of cro ss-linked tapioca starch and 17% of a high-amylose starch were compara ble to the clear noodles made from mung bean starch. (C) 1998 Elsevier Science Ltd. All rights reserved.