Ten different foods containing local Thai vegetables were selected to study their antioxidant and antimutagenic properties. The antioxidant capacity, antimutagenicity, and total phenolic content of methanol extracts obtained from cooked food samples exhibited a wide variation ranging from 24-140 mg vitamin C equivalent/100 g, 53-93% and 35-125 mg gallic acid equivalent/100 g. The three foods highest in antioxidant capacity were Kaeng Hoi Bai Chaplu (wild betal curry), Phat Sator (stirfried petai beans), and Kaeng Pa Gai (mixed vegetables curry). The foods that exhibited an antimutagenicity greater than 85% were Tomkathi Saibua (water lily stalk curry), Kaeng Pa Gai, Kaeng Taipla (southern curry), and Kaeng Lueang Khun (giant taro stem curry). Next, aiming to develop retort pouch food products, the effect of sterilization heat (121°C) on four selected foods was studied. Antioxidant capacity, antimutagenicity, and total phenolic content increased by 0-120%, 13-40%, and 6-54% after sterilization, respectively.

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.