| In the present dissertation,solid state fermentation technology of seafood surimi was studied,with emphasis on the effect of fermentation conditions and fermentation starters on physicochemical index,texture properties,protease activity,amino acids composition,TCA-N content and microbiological index of fermented surimi products.The main research results were as follows:1.The component of traditional seafood surimi was analyzed,and the effects of different additive formula and fermentation process on physicochemical and sensory index of surimi,and on the secretion of proteases by starters were studied.Based on these results,an optimized additive formula was obtained:salt 1%,glucose 2%,corn starch 5%,soybean isolated protein 10%,and water content(65±3)%;and the best culuture condition was temperature 30? and air humidity(90±5)%.Under these conditions,the starters grow well and can produce high level of protease(60 U/g),which is beneficial to the next fermentation process.2.The fermentation properties of two lactic acid bacteria(Lactobacillus plantarum and Pediococcus pentosaceus)as solid state fermentation starters of seafood surimi were studied.The effects of single inoculation and a 1:1 mixed inoculation of Lactobacillus plantarum and Pediococcus pentosaceus on protease activity,and physicochemical and microbial index of surimi were compared.Results showed that these two bacteria both have high acid-producing activity,and the pH of surimi was sharply decreased from 6.87 to 4.35-4.63 after 48h fermentation,and the total titration acidity was increased from from 0.08%to 0.62%-0.84%,while the pH and total titration acidity of the control group were 7.63 and 0.22%,respectively.Inoculation of these two kinds of bacteria clearly inhibited the growth of intestinal flora in fish surimi,which was 102-103 cfu/g after 48h fermentation.TVB-N concentration remained in a relatively low level,ranged from 7.83 mg/100g to 11.27 mg/100g,while the content of amino acid nitrogen increased from the original 0.043%to 0.30%-0.33%after 48h of fermentation.Fermentation didn't influence the water content and weight of the surimi,but improved the hardness,springiness and chewiness of the surimi.3.The fermentation properties of surimi with Mucor XH-22 and Aspergillus oryzae as starters were studied.The effects of single inoculation and a 1:1 mixed inoculation of these two strains on physicochemical index and protein hydrolysis of surimi were compared.Results showed that water content of the surimi decreased from 66.8%to(53.2-63.7)%during 48h of fermentation,pH decreased from 6.87 to 6.14-6.23,and the total titration acidity increased from 0.03%to(0.46-0.49)%,while the pH of the control group tended to firstly decrease and then increase,with a pH value of 6.97 after 48h of fermentation.The neutral protease activity in the surimi remained to a high level during the fermentation process(66.27-82.38)U/g(dry basis).Amino acid nitrogen,TCA-N,and free amino acids contents of the surimi increased with the increase of the fermentation time,and mixed inoculation group showed better results in degrading surimi protein and inhibiting the growth of other bacteria than the single inoculation groups.Through 48h of fermentation,free amino acids contents of the mixed inoculation group increased from 62.11 mg/100g to549.84 mg/100g,while the TVB-N level was below 30 mg/100g.Compared with lactic acid bacteria starters,lactic acid bacteria produced more acid while fungi secreted much more protease and further showed better protein-hydrolysis ability.4.Based on the above results,the surimi solid state fermented with fungi was further cured,post-fermented and flavored according to Xianheng fermented bean curd production process.And finally,a new flavored fermentation product,fish fermented curd,which showed good color,flavor and taste was obtained.This technology will provide some clue for the development of new products with sea-fish surimi as raw material in the future. |
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