Effect Of Three Chitin Derivatives On Quality Of Fresh Hot Dry Noodles And Mechanism Of Antioxidation

Hot dry noodles are a traditional breakfast and the most representative gourmet snack in Wuhan.Hot dry noodles are rich in protein,and the product processing process makes its moisture content higher compared with ordinary raw wet noodles,which is easy to breed microorganisms and oxidation and deterioration,and the selling period is short,which not only causes great waste but also seriously restricts the development of hot dry noodle industry.Based on this,this paper uses chitin derivatives such as chitooligosaccharides,oligomeric chitosan and chitosan as quality improvers to investigate their effects on wheat flour quality,fresh hot dried noodles product quality and the freshness,and further investigate the effect of quality improvers on oxidative browning and the antioxidant capacity in vitro of alkaline and heat-treated fresh hot dried noodles.First,various results of wheat flour quality showed that:wheat flour flour quality and tensile properties were significantly improved with the addition of chitosan derivatives,where water absorption was positively correlated with molecular weight size;and elongation results were inversely correlated with tensile resistance.The addition of the three sugars could effectively protect the starch and inhibit its breakage and pasting.The dry and wet gluten contents increased with the addition of the three sugars and the gluten index was enhanced,indicating that chitooligosaccharides,oligomeric chitosan and chitosan all enhanced the gluten network structure,but some of the results indicated that the addition of too much when the molecular weight was large led to an imbalance and the opposite result.After that,we studied the effects of three functional sugars on the quality of fresh hot dried noodles and storage period in detail.The results showed that after the addition of the three sugars,the product quality indexes improved significantly in the fresh samples and after 3 days of storage at 4^oC,and the hardness was increased with the increase of sugar molecular weight,and the tensile force also was improved.The cooking loss was significantly reduced by adding chitosan,but the cooking loss increased with the increase of sugar molecular weight.The deep bound water content of fresh hot dried noodles increased with the addition of the three sugars,and the water migration rate decreased with the addition of larger amounts.The addition of the three sugars strengthened the three-dimensional mesh structure and significantly increased the ordered structure and decreased the disordered structure in the protein secondary structure.The flour swelling potential of the pre-cooked noodle freeze-dried flour was significantly increased after the addition of the three sugars,indicating that the wheat flour with the addition of sugars still preserved its strong water absorption and swelling ability after pre-cooked.In terms of microorganisms,the microbial growth was significantly inhibited by the addition of chitosan derivatives after three days of storage at 4 ^oC,and the inhibition effect was more obvious with the increase of the added amount.Finally,we investigated the effect of chitosan derivatives on oxidative browning of fresh hot dried noodles before and after pre-steaming and their in vitro antioxidant capacity.The results showed that Among them,oligomeric chitosan and chitosan significantly improved the brightness whiteness of the noodles during 6-48h.During storage at 10 ^oC ambient temperature for 48-120 h,oligomeric chitosan showed a strong ability to inhibit oxidative browning,and the decay of L^*values was the smoothest and remained stable as the relatively highest among the four groups.After the addition of chitosan derivatives,the polyphenol oxidase（PPO）activity was significantly lower in both the raw noodles and the finished product after steaming compared with the blank group,and its activity was lower after steaming,and the degree of decrease was similar in all groups.Oligomeric chitosan with a relative molecular mass of 3000 Da showed stronger inhibition of PPO activity under alkaline environment（p H:8～10）and after short high temperature treatment.The free total phenol content increased with increasing molecular weight both before and after cooking,and the trend of free total flavonoid content in raw noodles was consistent with total phenol,while the opposite trend was observed after cooking.The scavenging rate of DPPH⁺free radicals and anti O₂^-·ability in raw noodles after the addition of the three sugars were inversely proportional to the molecular weight size,with the smaller the molecular weight the higher the scavenging rate.After pre-boiling,the scavenging rate of DPPH⁺radicals increased rather than decreased,and the scavenging rate of chitosan group was as high as90.82%.The anti O₂^-·ability and simultaneous decrease in the heat treatment were consistent with the raw noodles,and the blank group decreased to nearly zero.The fresh hot dried noodles with the addition of the three sugars had higher anti ABTS⁺radical ability and ferric ion reduction ability.The anti ABTS⁺radical capacity decreased after pre-boiling,but the decay of anti ABTS⁺radical capacity was significantly lower in the finished products with the addition of chitosan,while the iron ion reduction capacity showed a decreasing trend after boiling except for the group with the addition of chitosan.In summary,the results show that the addition of chitooligosaccharides,oligomeric chitosan and chitosan can effectively improve the fresh and storage quality of fresh hot dried noodles and significantly delay the oxidative browning of noodles while enhancing the in vitro antioxidant capacity.This paper provides a theoretical reference for the application of chitosan derivatives in fresh and hot dried noodles and related products,and thus promotes the development of related industries.