b. Lemon grass fiber-added frying batter of chicken nuggets
In this section, lemon grass fiber was incorporated into frying batter in order to reduce oil uptake in fried products. Batter pick-up before frying, oil uptake and water removed after frying influenced by the addition of fiber were investigated. Batter pick-up was increased when 2 and 3% lemon grass fiber were added into frying batter. During the preparation, it was observed that increased fiber addition level resulted in increased batter viscosity, which made the value of batter pick-up higher. Normally, batter pick-up increases with increased batter viscosity, which enhances the formation of a hard crust during frying. The crust serves as a barrier to prevent water loss, and therefore contribute to reduced oil absorption. However, when the batter had poor film-forming properties, the increase in pick-up due to increased viscosity did not provide an effective oil-resisting property (91). Hence, good film forming has been reported to be one of the desirable characteristics for lowering oil absorption in batters (92). Good film-forming property of fiber has been reported to be associated with its good thermogelation property as mostly exhibited in cellulose derivatives, e.g. methylcellulose (MC), carboxymethyl cellulose (CMC) and hydroxypropyl methyl cellulose (HPMC), which made them suitable and popular for use to reduce oil uptake in fried products (93, 94). On the contrary, powdered cellulose without any modification did not provide film-forming capacity, meaning that higher batter pick-up as a result of cellulose addition could not contribute to the effectiveness of oil uptake reduction (62). Because lemon grass fiber was supposed to contain mostly cellulose, increased batter pick-up of lemon grass Fac. of Grad. Studies, Mahidol Univ. M.Sc.(Food and Nutrition for Development) / 63 fiber-added batters resulted from increased batter viscosity might not take part in the reduction of oil uptake. The moisture and fat contents of all products before frying were the same, meaning that the changes in final values of moisture and fat content after frying were related to the differences in oil uptake for the fried batters. With increased level of lemon grass fiber addition, the values of water removed and oil uptake decreased. Three percent lemon grass fiber-added batter showed the lowest value of water removed after frying with percent reduction about 23% compared with the control formula followed by 10% reduction in 2% lemon grass fiber-added batter. Similarly, oil uptake was most reduced in case of 3% lemon grass fiber addition with around 40% reduction from the control, while 2% fiber addition resulted in 17% reduction. These findings were agreeable with the study of Ang et al. that 3% addition of cellulose, soy fiber, oat fiber as well as pea fiber in batters appeared effective for reducing oil absorption at varying degree (54). Additionally, it was observed that the appearance as well as the crispiness of chicken nuggets coated with lemon grass fiber-added batter was not different from that of the control. The effectiveness of dietary fiber in lowering oil uptake could be attributed to its water holding capacity since water retained inside batters served as a barrier for oil absorption during frying, meaning that the more water retained in the fried batter, the less oil absorbed. The results from this study revealed that water holding capacity of lemon grass fiber was high enough to be used as an oil-uptake reducer in frying batter without affecting the quality of the battered products by adding at the amount of 2 - 3% based on total weight of commercial batter mix.