The effect of blanching and firming agent on the quality of blanched sweet potatoes / Haslinda Shukor

Low-temperature-long-time (LTLT1 as opposed conventional-high temperature - short -time (HTST) blanching was applied to produced firmer texture of blanched sweet potatoes. This study was carried out to determine the effect of the low temperature blanching and a; high temperature short time blanching and the effect of firming agent during soaking and blanching on the firmness sweet potatoes. The physicochemical analysis was conducted which includes texture measurement by Steven Analvzer. TSS, peroxidase test and ascorbic acid determination. The texture of blanched sweet potatoes increases with the increased of soaking time. The Duncan Multiple Range Test shows that there is significant different (p<0.05) on the texture of blanched sweet potatoes at 50°C; 70°C and 90°C using water blanching. For the steam blanching treatment, there is no significant different (p<0.05) in the texture at 105°C, 110°C and 1 i5°C. Combination of water and steam blanching shows that there is no significant different (p<0.05) in the texture. High temperature-short time by steam blanching at I05°C/9minutes is effective to inactivate peroxidase enzymes. The addition of 0.1% CaCl increased the texture of blanched sweet potatoes (181.3 load/g) compared to without addition of CaCl (176.0 load/g). The Duncan's Multiple Range Test shows that there is no significant different on the texture of blanched sweet potatoes poaking in CaCl for 30 minutes, 1 hour and control sample. The increasing of the soaking time to 2-4 hour have significant effect on the texture of sweet potatoes compared to control, 30 minutes and 1 hour soaking time. The increased of calcium chloride concentration will increased the texture of blanched sweet potatoes dramatically than increasing the soaking time. Analysis of ascorbic acid in the blanched sweet potatoes shows that the losses for sample treated with 0.1 % and 0.5% CaCl is belween 72% to 74%. However, for untreated sample, the loss is slightly lower (66.9%). Total soluble solid content remain the same, before and after (1.6 to 1. 9°Brix) water blanching and steam blanching.