| With the increasing production of tilapia, tilapia how to deal with waste to avoid wasting this issue should also be cause for concern. Tilapia skin because of high nutritional value, low cost, so there is a high economic value. Therefore, on the basis of previous studies on the enzyme with edible, edible alkali, edible acid on the skin of dried tilapia made up a systematic study found that skin treated different production rate, sensory evaluation, TPA values shear force, color and other aspects have a significant impact, and optimize the optimal process conditions. Combining texture analysis, color analysis and SEM image analysis and preliminary study of its mechanism. Specific results are as follows:1.Optimization of enzymatic treatment conditions: It was found that the enzyme pre tilapia skin to improve the hardness and color to a certain extent, screened papaya papain, bromelain, pepsin, neutral protease, alkaline protease, trypsin protease as for the study, using a single factor and orthogonal experiment to optimize the enzyme treatment conditions. The results show that: the enzyme added will reduce the shear force, tilapia skin tenderness has greatly improved. Tilapia white skin color becomes more transparent. Optimal treatment conditions are: the concentration of papain 2%, treatment temperature 60 ℃, the processing time of 25 min. In this case the highest sensory score of 4.5 points, shear force is 7.8N. In this case, the moisture content is 60.52 ± 0.49, produced was 130%, L * value of 55.41 ± 0.25, a * value of 1.45 ± 0.23, b * value of 8.79 ± 0.10.2. Optimization of alkaline treatment conditions: It was found that by pre-base to improve the production rate of tilapia skin have some positive effects in selected sodium hydroxide, sodium bicarbonate, sodium carbonate as the base of these three studies object, select the amount of alkali, alkali treatment temperature alkali treatment time as the main factors affecting the skin sensory indicators, selected by single factor experiment and response surface level factors, tilapia skin sensory evaluation of response. By response surface optimization of the conditions of alkali treatment: sodium hydroxide concentration of 2%, the processing time was 6h, the treatment temperature is 25 ℃, resulting tilapia skin sensory score of 4.7. Theoretical and sensory score closer to 4.7229. In this case, the measured moisture content of the skin was 80.48 ± 2.1, produced was 270%, L * value of 63.89 ± 0.13, a * value of 1.41 ± 0.17, b * value of 4.42 ± 0.05. Shear force 20.81 N, hardness.3. Optimization blanching test conditions: by single factor and orthogonal experiment to study different blanching temperature(75%, 80%, 85%, 90%, 95%) blanching time(5s, 10 s, 15 s, 20 s, 25s), liquid ratio(30 times, 60 times, 90 times, 120 times, 150 times) on tilapia skin sensory evaluation. Optimize the best treatment conditions blanching test were: blanching temperature of 80 ℃, blanching time 15 s, liquid to solid ratio of 90: 1, then the sensory score of 4.5. In this case, the measured moisture content of the skin was 66.42 ± 2.1, produced was 220%, L * value of 57.82 ± 0.23, a * value of 1.38 ± 0.17, b * value of 4.02 ± 0.05.4. Optimization of acid treatment conditions: by preliminary experiments have found that addition of the acid production rate of tilapia skin and TPA values are significantly improved role. Especially after the skin after blanching step after production rate decreases. Therefore the choice in acetic acid, hydrochloric acid, citric acid and citric acid as the research object, based on the single factor experiment, select the acid concentration, acid treatment, acid treatment temperature as independent variables, tilapia skin sensory evaluation, was produced response, using Box-Behnken central composite design optimization optimum conditions were: 1.5% acid concentration, acid treatment time of 13 h, the acid treatment temperature is 20 ℃. Under this condition, the skin sensory score 4.7, produced was 331% with 4.72054 theory sensory score, the production rate compared to 332.175%, closer. In this case the measured skin moisture content was 92.26 ± 0.66%. L * value of 69.89 ± 0.13, a * value of 1.01 ± 0.17, b * value of 2.44 ± 0.26, shear force is 7.52 ± 0.49 N.3.Compare the effects of different reagents tilapia skin structure by scanning electron microscopy: Compared with the control group, dense skin structure and skin structure increasingly loose the other three groups. Swelling of collagen fibers, making the gap between the collagen fibers become smaller, it becomes more and more closely, the skin tissue to achieve full expansion, resilient state.This may occur in conjunction with each other between the collagen protein in a basic group or an acidic group with an acid or a base, ionic crosslinks between collagen molecules and hydrogen bonds between the peptide chain and will damage the collagen structure is loose, it The swell phenomenon appears absorbent. In addition, proteases can break down the skin tissue proteins, protein structure will be destroyed, part of a peptide bond breakage occurs, collagen degradation to small peptides. The tissue expansion, texture becomes tender. Water will enter between the cell and between cells, to water swelling effect. |
PDF Full Text Request