No abstract

Frozen food products are gaining acceptance in Thai food industry and frozen bualoy dessert is a good opportunity for marketing in domestic and for exports. One important factor affecting quality of frozen starchy foods is retrogradation of starch gels. Thus freeze‐thaw stability of a frozen bualoy made from total waxy rice flour was studied and compared among the samples modified by 20 and 30% cross‐linked tapioca starch (CTS) derivatized with phosphorylation and 0.25% propylene glycol alginate (PGA). The waxy rice flour was pregelatinized by adding boiled water before shaping as a ball, then boiled and mixed with coconut syrup. All samples were subjected to five freeze‐thaw cycles over 60 days in a conventional freezer (–18°C). Texture analysis firmness and stickiness of the nonfrozen gels substituted with 20% CTS (382 ± 43, 20.5 ± 7.1 g·f) and 30% CTS (493 ± 37, 31.1 ± 7.0 g·f) were significantly different as compared with the control (329 ± 22, 14.8 ± 3.1 g·f). Similar results were observed for the samples continuously frozen for 60 days. The effects of freeze‐thaw stability to the frozen gels of the control, CTS, and PGA substituted samples appeared after two cycles and exhibited a large increase in firmness and stickiness at the fourth cycle. The firmness values obtained from the control and the samples substituted with 20% and 30% CTS were 2,397 ± 197, 2,182 ± 203, and 2,104 ± 200 g·f, respectively. This evidence was also observed with the samples containing PGA, but the effect was slightly less. This might account for the recrystallization of amylopectin molecules induced by freeze‐thawings. With DSC, the waxy rice gels showed a significant increase in the melting enthalpy (2.39 ± 0.23 J/g) at the fifth cycle from the nonfrozen gels (0.11 ± 0.02 J/g). The sensory tests of the bualoys were correlated with textural qualities that were acceptable to the panelists when the freeze‐thawing went no further than the second cycle.

Hydrolyzed oat flour, called Oatrim, was found able to cr eate suitable food desserts when partially substituted for butter or coconut cr eam. In bakery pr oducts, a 25% Oatrim gel was substituted for butter in rice cookie, br ownie, and banana cake r ecipes. The cholester ol contents of the rice cookie, banana cake, and br ownie wer e reduced by 24.7%, 13.5%, and 24.1%, r espectively. Coconut cream was replaced with a 15% Oatrim suspension in the Thai desserts coconut custar d, coconut cream spread, and mungbean conserve. In these pr oducts, a substantial r eduction in saturated fat content was found: coconut custar d (60.6% reduction), mungbean conserve (76.4% r eduction), coconut cream spread (83.7% reduction). Although adequate textur e measurements wer e observed for most par- tially substituted products, the breaking strengths of the rice cookie and mungbean conserve wer e significantly increased over control foods. These data suggested that the use of the gel should be limited to less than 50% of the substitution. W ithin the experimental parameters examined, the baked goods and Thai desserts exhibited satisfactory sensory qualities in the 50% to 60% substitution range.