82-4

G. Kaletunç, Dept. of Food, Agricultural & Biological Engineering, Ohio State Univ., 590 Woody Hayes Dr., 210 Agricultural Engineering Bldg., Columbus, OH 43210-1058 and A. KING, Food Agricultural and Biological Engineering, The Ohio State Univ., 590 Woody Hayes Drive, Columbus, OH 43210.

High hydrostatic pressure (HHP) processing has been investigated as an alternative to thermal processing. HHP processing has been known to denature the proteins and gelatinize starch at ambient conditions. Gelatinized starch recrystallizes during storage affecting the texture and shelf life of food products adversely. This study aims to evaluate and compare the effect of storage temperature on the crystallization and rheological properties of HHP processed corn and wheat starch. Starch suspensions (15% w/w) were treated with HHP at 600 MPa and 25 ^o C for 15 min. Crystallization at 4 and 23 ^o C was monitored by measuring thermal and rheological properties of HHP processed starch using a DSC and a rheometer. DSC thermograms were recorded from 1 ^oC to 100 ^oC at 5 ^oC/min heating rate. The melting enthalpy of starch crystals was calculated and fitted to the Avrami Equation ΔH(t)- ΔH(i)/ ΔH(f)- ΔH(i)=1-exp(-ktⁿ) to determine crystallization kinetics parameters. A cone-and-plate geometry was used to perform dynamic rheological tests. Stress sweep experiments were used to determine the linear viscoelastic region followed by frequency sweep tests over the frequency range of 0.1 to 50Hz to determine storage modulus and loss modulus. The DSC results showed that the amount of re-crystallized starch increased during storage for both corn and wheat starch, although the rate and the extent of crystallization depended on the temperature and botanical origin. Wheat starch stored at 23 ^oC exhibited the least amount of crystallization as well as the least structural loss as quantified by storage modulus, maintaining its physical stability during storage over 40 d. Characterization of physical properties of starch as a function of high pressure processing conditions provides a valuable data base for optimization of processing protocols and storage conditions in order to improve physical stability and textural characteristics of food products in addition to their safety.

Session 82, Carbohydrate: General
2:30 PM - 5:30 PM, Tuesday PM Room 392

2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana