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Oat Enzyme Activity And Its Deactivation For Oat Food Processing

Posted on:2008-08-15Degree:DoctorType:Dissertation
Country:ChinaCandidate:X Z HuFull Text:PDF
GTID:1101360215994622Subject:Food Science
Abstract/Summary:PDF Full Text Request
To solve the problems that the obstacles affected naked oats (Avena nuda) for food processing in China, this research focus on the key facors, which as enzyme activity, debranned for oat rice, mouthfeel improvement, and oat processing releated factors as breakthrough point, the naked oats varieties VAO-2 and others were used to compare the enzyme distribution, enzyme deactivation, and developed the oat-rice, oat-wheat flour for staple food processing. The purpose was to push the oats as the future staple food crops followed by rice and wheat.The results showed that micronizing was a very good method for enzyme deactivation, at the same time, the oat food mouth feel was improved, and the technology obstacle which limiting oat food development had been removed, it would be the basic knowledge for pushing the oat as the future staple food.1. The results releated with lipase enzyme distribution showed: lipase activity had positively significantly correlated with kernel length, width, areas, and one thousand kernel weight, but negatively related with ratio of kernel weight divided by area. The bigger the kernel, the lower the lipase activity was. Lipase activity was negatively correlated with oat debran ratio, and lipid content. The oat rice got after 20s debran was higher in kernel whiteness, lower loss ofβ-glucan, and proten content. 20s debran with Japan Satake mill was selected by the best technology as oat rice development. It provided the basic foundament for naked oat kernel and oat rice enzyme deactivation.2. The results from different enzyme deactivation methods showed: normal pressure steaming, autoclaving, and micronizing can kill the lipase and peroxidase of naked oats, dry roasting can't deactivated these enzymes. The tempring content was very important for micronizing, 20% moisture was the deadline for deactivation, and 18% tempering moisture content didn't work. Kernel size was another key factor affected micronizing results. Small kernel (average single kernel weight 18.4mg) was diffculty to get the exactly deactivation results than mixed kernel (average single kernel weight 23.7mg). The third key factor for micronizing is temperure keeping after micronzing; 6h was minimum period for totally deactivation. Micronzing was a very good technology for oat processing, it combined the roasting and steaming technology together, and work time was very short until 18s. 3. The results for oat-rice deactivation showed: normal pressure steaming, autoclaving, and micronizing can deactivate the lipase and peroxidase of naked oats, dry roasting can't kill these enzymes. Tempering time was greatly affected the enzyme deactivation, longer than 3h will make some enzyme couldn't be killed. Also, temperature keeping for 6h was another important index for enzyme evulation. It prepared the stong basic knowledge for oat rice food development.4. The scanning electronic microscopy and florense microscopy photo for treated oats kernel showed: The starch granule had been gelatinized and sticked together after steaming and autoclaving. The starch had been broken out from micronized oats kernel. The sequence of peak viscosity for oat kernel from high to low was normal steaming, autoclaving, micronzing, normal roasting, and then naked oats check.β-glucan was the main bidge for oat cell connection. Lipid was mostly distributed along the kernel out-bran and germ. The enzyme treatment had no significantly effect for the lipid, andβ-glucan content. It provided the evulation methods for enzyme deactivation and quality change.5. The results related oat food processing was: Compared with wheat flour, oat flour has lower albumin, gliadian content, higher globulin content, and a little lower in glutenin content. The oat flour has higher peak viscosity, maximum viscosity and final viscosity than wheat flour. The wheat flour dough mixed oat flour had longer dough development time, but shorter stability time. Substituted the oat flour with the same proportion wheat starch, the specific volume and sensory evaluation score of bread and steam bread reduced, the noodle water absorption and total evaluation score reduce but water loss increase. The starch has significantly effects for food quality index when substitution level higher than 5%.The best oat flour mixture proportion for noodle, steam bread and bread making was 10%, 25% and 10%. It would be the important method for pusing the oat as the future staple food. The effects of Artemisia sphaerocerphala kraschen (or ASK) and vital gluten for oat products processing quality was: The vital gluten was the biggest effect to bread processing. The ASK was the biggest effect to steam bread making. The combined effect of the ASK and vital gluten is greater than their single effect. The best formula of oat whole meal bread and steam bread is 2.5% ASK and 8.0% vital gluten. For frozen dough processing, freezing time has significantly effect to bread volume and sensory score, and significantly to steam-bread volume and sensory score. The quality of the frozen dough decreased gradually with the time passed, the oat whole meal processing quality of bread and steamed bread became worse 4 days later. The ASK and vital gluten can be used as the nature improver for oat whole meal food processing.6. The results related oat-rice and oat-wheat flour processing quality was: Combined 1/3 of the oat with 2/3 of rice could be used to develop oat-rice products, combined 1/3 of the oat flour with 2/3 of wheat flour for oat-wheat flour products development. The ratio between wheat: rice: oat = 2/3: 2/3: 2/3, the wheat, rice, and oat was equal and all of them came to the table as the same amout, and satisfied with our proposal of"oat as third staple food". 10%, and 20% deactivation oat flour blended with 90% and 80% wheat flour can be processed good quality bread, and their bread volume had no significantly difference. Seneory evaluation score of oat-rice as the proportion 10%, 20%, and 30% of oat mixed with rice had no significantly difference.Naked oats and oat rice combined with the micronzing technology provided the basic principle and protocol to develop the proposal of oat as future staple food.
Keywords/Search Tags:Naked oats (Avean Nuda), Enzme activity, Micronzing, Oat rice, Future staple food
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