Abstract:
This study focused on the effect of biopolymers on benzo (a) pyrene (BaP) contents in smoked fish. Batrachian Walking Catfish (Clarias batrachus Linnaeus) used was composed of 70.19% moisture, 17.43% protein, 12.43%fat and 0.01% ash. The total volatile base (TVB) contents of the flesh fish was 11.31 mg/100g. Three levels of the bagasse moisture contents, 10, 20, 30% and the smoking temperatures of 50 and 60℃ were tested in the smoking process. The best quality product was selected by determining BaP contents and sensory quality. Later, the effect of biopolymer concentrations at different coating layer thickness were studies. The biopolymer solutions studied were: hydroxypropyl methylcellulose (HPMC, at 1.33, 2.44 and 3.80%w/w). methylcellulose (MC, at 3.54, 5.57 and 7.84%w/w) and hydroxypropyl cellulose (HPC, at 3.42, 5.54 and 7.60%w/w). The best quality product from each biopolymer was selected by determining the apparent viscosity, the coated weight per unit area of the film solution, moisture, firmness, color (L, a*, b*) BaP and sensory quality of the coated and uncoated smoked fish samples. Later, the effect of biopolymer concentrations of equal thickness layer were studied. The biopolymer solution studied were: HPMC at 1.69, 2.44, 3.26%w/w MC at 4.31, 5.57, 6.63%w/w and HPC at 6.93, 7.60, 8.24%w/w. Finally, the efficiency of the three biopolymers were compared and the best material selected by using BaP, biopolymer cost and sensory quality as criteria. The results showed that optimum smoking process obtained at 20% bagasse moisture content and 50℃ Smoking temperature. BaP contents under this condition were 2.07 ppb surface, 0.31 ppb and 2.38 ppb total. The effect of biopolymer at different thickness layer revealed that as the concentrations of HPMC, MC and HPC increased their apparent viscosity increased and resulted in the increases of the coating weight, moisture, firmness, lightness and yellowness but the redness and sensory quality decreased. The optimal HPMC concentration was 2.44%w/w, at this level, the BaP found was 0.75 ppb on surface, 0.17 ppb inside and 0.92 ppb total. Optimal MC concentration was 5.57%w/w, at this level, the BaP found 0.80 ppb on surface , 0.15 ppb inside and 0.95 ppb total. Optimal HPC concentration was 7.60%w/w, at this level, the BaP found was 0.89 ppb on surface, 0.12 ppb inside and 1.01 ppb total. When the thickness of the biopolymers were controlled, it was found that concentration increase did not affect the moisture contents, color and sensory quality of the coated products. The optimal HPMC concentration was 3.26%w/w, at this level, the BaP found was 0.77 ppb on surface, 0.08ppb inside and 0.85 ppb total. Optimal MC concentration was 5.57%w/w, at this level, the BaP found was 0.77ppb on surface, 0.13 ppb inside and 0.90 ppb total. Optimal HPC concentration was 6.93%w/w, at this level, the BaP found was 1 ppb on surface, 0.21 ppb inside and 1.21 ppb total. Finally, the efficiency of three biopolymers were compared, it was found that the best and most acceptable material was 3.26%w/w HPMC which resulted in the product with good sensory quality, the lowest level of BaP and the lowest cost of coating material.