C: Food Chemistry JFS C: Food Chemistry Using Ozonation and Amino Acids to Change Pasting Properties of Rice Starch H.J. AN AND J.M. KING ABSTRACT: In this study, the effects of ozonation and the addition of amino acids on rice starches were determined in terms of pasting properties using a rapid visco-analyzer. Results from viscosity analysis showed that 30-min ozone treatment on commercial rice starch exhibited the greatest swelling extent among the treatments and least retrogradation tendency. The control pure oxygen treated sample had the best cooking stability. The addition of lysine (6%) to 30-min ozonated commercial rice starch significantly reduced peak viscosity (PV), minimum viscos- ity (MV), and final viscosity (FV) by 918, 1024, and 1023 cP, respectively. Moreover, it decreased Ptime, resulting in the faster swelling upon heating and less rigid gel formation upon cooling. Furthermore, the presence of lysine in 30-min ozonated starch isolate (WSI) also significantly reduced PV, MV, FV, pasting time, and total setback (TSB) and produced starch gel with the best cooking stability and the least retrogradation tendency. Ozonated starch exhibited similar pasting properties to those from oxidized starches treated with low concentrations of chemical oxidizing agents. The combination of lysine with ozonation resulted in pasting properties similar to starches treated with high levels of chemical oxidizing agents. The ozonated starch could be used as a thickening agent, whereas ozonated starch with lysine might be an alternative for a highly chemically oxidized starch. Therefore, ozonation alone or the combination of ozonation and addition of lysine might be used to develop new starch ingredients with various functionalities without using typical chemical modifications. Keywords: amino acids, ozone, pasting, rice starch, viscosity Introduction A mylose content and quantitative and qualitative differences in the various noncarbohydrate constituents, such as lipid and protein affect pasting characteristics of starches (Mangala and oth- ers 1999). Hamaker and Griffin (1993) studied the effect of protein on the pasting behavior of starch granules and found that depro- teinization produced starch granules that were more fragile allow- ing more water into the granules, resulting in increased viscosity because of greater swelling. Radosavljevic and others (1998) also concluded that amaranth starch treated with alkaline-protease had a greater amount of starch yield and recovery, and showed greater pasting by amylograph. Ravi and others (1999) observed that glyc- erol monosterate (GMS) decreased peak viscosity (PV) by reduc- ing starch swelling because of the adsorption of lipid on the starch granule surface, and that protease treatment reduced the PV and fi- nal viscosity (FV). Furthermore, Biliaderis and Tonogai (1991) con- cluded that defatted starches increased viscosity, explaining that granular lipids inhibit amylose leaching from the granules during gelatinization so that a softer starch paste was produced. Starch granule swelling was decreased when lipids are present (Tester and Morrison 1990; Tester and others 1991). Moreover, added oleic acid in extrusion reduced paste viscosities (Schweizer and others 1986). Amylose–lipid complexes in nonwaxy starch decreased vis- cosities and showed pseudoplastic behavior, which was suitable for semisolid food applications (Guraya and others 1997). Liang and King (2003) found that the addition of charged amino acids affected the pasting characteristics of rice starch. Lockwood and King (2008) found that pasting properties of sweet potato starches can be al- tered by the addition of amino acids. MS 20080766 Submitted 10/1/2008, Accepted 1/30/2009. Authors are with Dept. of Food Science, Louisiana State Univ. Agricultural Center, 111 Food Science Bldg., Louisiana State Univ., Baton Rouge, LA 70803, U.S.A. Direct inquiries to author King (E-mail: jking@agcenter.lsu.edu). The main desired effects of oxidation are lower viscosity and im- proved stability of starch dispersions (Hebeish and others 1992; Forssell and others 1995). It was found that oxidation decreased paste viscosities attributing to loss of swelling capacity of oxidized field pea starches (Li and Vasanthan 2003). Reduced capability of gel formation and increased stability were found with an increased degree of oxidation in cornstarch (Han 2002). Oxidation reduced PV and resulted in lower setback in cooled paste (Han and Ahn 2002). Oxidized starch was found to contribute to a lower viscosity but to exhibit an increased fluidity of starch paste due to molecular oxidative scission (Wurzburg 1986). Thiewes and Steeneken (1997) found that viscosity was reduced with increased degree of oxida- tion; and pasting temperature (PT) and the time to peak (Ptime) were also lower than untreated sample. Wurzburg (1972) explained that carbonyl and carboxyl groups formed on the starch molecules in oxidized starch are bulkier than hydroxyl groups, resulting in a reduction in the tendency to associate. Chemical agents used for oxidation of starches can create chemi- cal waste problems and potentially leave undesirable residues in fi- nal products. Ozone is a known as a powerful oxidizing agent. Thus, ozone treatment may be a good alternative to chemical treatment, as ozone does not leave any solvent residues when utilized on a food product. The objectives of this study were to (1) evaluate the effect of ozonation on pasting properties of rice starches and (2) to see if there was synergistic effect between ozonation and amino acids in altering the pasting properties of rice starches. Materials and Methods Materials Rice starch was purchased from Sigma Chemical Co. (S7260; St. Louis, Mo., U.S.A.) while white rice flour was obtained from Riviana Foods Inc. (Abbeville, La., U.S.A.). The 3 different amino acids utilized included positive charged (lysine), negative charged C278 JOURNAL OF FOOD SCIENCE—Vol. 74, Nr. 3, 2009 C  2009 Institute of Food Technologists R  doi: 10.1111/j.1750-3841.2009.01109.x Further reproduction without permission is prohibited