| In this research, oat (Avena stativa L.) was choosen as the main material, add certain proportion of bran and soybean meal, Aspergillus oryzae3.042was used as fermentation strain, aimed to ferment oat sauce. Mainly studied the optimization of the process parameters of koji-making and insulation fermentation process and the change of physicochemical properties during insulation fermentation and after fermentation process, the effect of sterilization on the quality of oat sauce and the correlation of the antioxidant capacity and total phenolic content of oat sauce was studied at the same time. The main conclusions of this paper were as followed.1The process parameters of koji-making and insulation fermentation process were optimized based on the Response Surface and orthogonal experiments. The Optimal koji-making conditions can be concluded as follows:fermentation temperature33℃, noculum size0.5%and fermentation time37.4h. Under above conditions, the protease activity of oat koji was0.95±0.02(g amino nitrogen/100g md). The optimal conditions of the insulation fermentation process were as follows:ferment temperature43℃, salt concentration15°Be, ferment time14d. Under above conditions, the content of amino nitrogen in oat sauce was0.88±0.01g/100mL.2Changes of microbiological indicator, physicochemical properties and sensory properties during insulation fermentation were studied, the results show that:molds, yeasts and lactic acid bacteria colonies were significantly decreased in the initial stage of fermentation (P<0.05), the trend of the number of molds colonies was not significant3days later (P>0.05), and the viable bacteria was not detected in the9th day; the number of yeasts colonies was decreased significantly (P<0.05) and there was no viable yeast in the7th day. The content of amino nitrogen was significantly increased initially (P<0.05), keep stable for some time and then increased initially again (P<0.05), then eventually stabilize; the total acid content increased significantly initially (P<0.05), then keep stable; the reducing sugar content increased initially and then decreased significantly (P<0.05), and finally stabilized. During this period, the sensory properties had a good change:bright reddish brawn, rich Maotai-flavor smell.3Changes of microbiological indicator, physicochemical properties during after fermentation were studied, the results show that:the number of lactic acid bacteria and yeasts colonies were significantly increased initially(P<0.05), then decreased significantly(P<0.05), showed complicated interaction. Amino nitrogen and color had no significant change (P>0.05); total acid content increased with time, the trend was significantly during the first7days (P<0.05), then keep stable (P>0.05), followed by a significant increase9days later(P<0.05); reducing sugar content gradually reduced with time, the trend was not significant in the first5days(P>0.05), then significantly reduced during5to13days (P<0.05), and finally achieved stability.4The effect of thermal treatment(70℃,20min;75℃,15min;80℃,10min) and ultra high pressure treatment (100MPa,25min;200MPa,20min;300MPa,15min) on the sensory properties of oat sauce was studied, the results show that:the sensory scores of sterilized sauce were lower than the original sauce. After ultra high pressure sterilization, the color, shape, aroma and taste of oat sauce had no significant difference (P>0.05); the sensory score was higher than the other2thermal treatment under80℃for10min, there was a significant difference in color, body, aroma scores and the total score between the treatment under80℃for10min and the other two sets of thermal sterilization (P<0.05), thus filter out heat sterilization conditions were as follows:sterilize temperature80℃, sterilize time10min.5Compared the effects of heat treatment (80℃,10min) and ultra high pressure treatment (100MPa,25min;200MPa,20min;300MPa,15min) on the physicochemical properties and color of oat sauce, the results show that:after sreilization with4kinds of sterilization methods, the total number of colonies of the sauce was up to the standard of EU Microbiological Criteria for Foods (≤100CFU/mL). After ultra high pressure treatment, total nitrogen, total acid content of oat sauce had no significant difference compared to the original sauce (P>0.05), but the amino nitrogen, reducing sugar content decreased significantly (P<0.05); After heat treatment, total nitrogen content had no significant difference compared to the original sauce (P>0.05), but the content of total acid, amino nitrogen and reducing sugar were decreased. Compared to the original sauce, the trends of color change of treated sample were the same. L*and b*increased, a*significantly decreased (P<0.05). The amino acid detection results show that:there were16kinds of amino acids, including seven kinds of essential amino acids in the oat sauce. Compared with the original sauce, those treatments caused some loss of amino acid but not much. Viewed from the retention of nutrients and color, filtered out ultra high pressure treatment conditions were as follows:sterilize pressure300MPa, sterilize time15min. 6The effect of heat treatment (80℃,10min)and ultra high pressure treatment(300MPa,15min) on the mainaroma constituents in oat sauce was studied using solid phase micro extraction (SPME) combined with meteorological chromatography-mass spectrometry (GC-MS) method. The results show that:the kinds of aroma substances in the treated oat sauce were less compared with original sauce, were66.20%of the original sauce, illustrated that heat treatment and ultra high pressure treatment had a great influence on aroma substance in oat sauce, but there was on big difference between the two ways. The main aroma substance of oat sauce were tethyl oleate, ethyl palmitate and ethyl linoleate.7The correlation of the antioxidant capacity and total phenolic content of oat sauce was studied, the results show that:the order of reducing power, superoxide anion scavenging activity and DPPH radical scavenging activity were the same:thermal treated sauce>300MPa,15min ultra high pressure treated sauce> original oat sauce>100MPa,25min ultra high pressure treated sauce>200MPa,20min ultra high pressure treated sauce> VC; the order of·OH scavenging activity were: thermal treated sauce> original oat sauce>300MPa,15min ultra high pressure treated sauce>100MPa,25min ultra high pressure treated sauce>200MPa,20min ultra high pressure treated sauce> VC; the Reducing power, Superoxide anion scavenging activity,-OH scavenging activity and DPPH radical scavenging activity of oat sauce all had high correlations with the total phenolic content, the Correlation coefficients were0.833,0.974,0.889and0.850. |
PDF Full Text Request