| Currently, synthetic antioxidants are widely used in food to inhibit lipid oxidation and extend shelf life, etc. and have achieved good results, but in consideration of the food safety, our country has limited its applications. Therefore, the study on natural antioxidants extracted from plants instead of the synthetic antioxidants is very important. Rice bran has varieties of biologically active ingredients, such as dietary fiber, tocopherol, oryzanol, etc., is a good sources of natural antioxidants. Rice bran not only can be used as an antioxidant in foods, but also has a potential efficacy beneficial to human health, such as to remove the body radicals. In this study, rice bran as raw material, the rice bran alcohol extractive has strong antioxidant activity, and studied the antioxidant activity, stability and antioxidant effects in the meat of the extractive.1,Determine the optimum extraction conditions of rice bran by single factor test and response surface experiments:ethyl alcohol as the extraction solvent, The optimum extraction temperature is60℃, reaction time5h, solid-liquid ratio15mL/g, rotary evaporator before freeze-dried. At this point, the antioxidant of rice bran extractive achieved the strongest.2,Evaluated the antioxidant activity of rice bran extractive. The extractive1mg/mL was compared with O.Olmg/mL BHA and ascorbic acid on antioxidant capacity respectively. The extractive is higher than ascorbic acid and BHA at DPPH radical, hydroxyl radicals, and scavenging rate of superoxide radical. However, reducing capacity of extractive is significantly lower than ascorbic acid and BHA, chelating ability of Fe2+in between.3,Antioxidant activity of rice bran, When the concentration of alcohol extractive of rice achieved3mg/mL, the clearance rate of DPPH· was67.81%, scavenging rate of superoxide radical was73%, reducing capacity can be0.9, hydroxyl radicals scavenging capacity can be70%. And with the concentration of rice bran increased, a variety of antioxidant capacity increased in varying degree.4,Stability of rice bran alcohol extractive, The rice bran extract was heated in a water bath at different temperatures, With heating temperature and heating time increasing, DPPH, hydroxyl radicals, superoxide radicals and reducing capacities of RBC (The extraction of rice bran with C2H5OH) are declined in different degrees, the higher the temperature and the longer the heating time, the more reduced. Placed the rice bran extractive under natural light in outdoor, natural light indoor and dark conditions to25d, and then measured the antioxidant activity of RBC.The results showed that illumination lead to a reduce of antioxidant capacity of the extractive. Lower order:outdoor natural light indoor natural light dark.Antioxidant activity of RBC was more stable at lower pH conditions, higher pH have a greater impact on the antioxidant activity of RBC.5,Impact of RBC to meat Different concentrations of RBC was added to the meat, stored at4℃and determination of TBARS value of meat, carbonyl content,thiol content, the total bacterial counts and pH. The results show that the rice bran extractive can reduce the value of TBARS of meat, inhibition lipid oxidation, and the larger the additive amount, the stronger the inhibitory effect; the extractive can reduce the amount of the carbonyl group and reduce the loss of thiol groups and inhibition the oxidation of proteins, but the effect of inhibition is not obvious than the inhibition of fat oxidation. |
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