Study On Change Of Quality Of Frozen Noodles During Frozen Storage

The noodles are a typical success example of traditional food industry, in2012the output valuereached400million yuan. Freezing was primary means of noodles products. Research of frozen noodlesquality in storage was important for improvement of noodles quality.The effects of frozen storage on thenoodles quality, chemistry composition and microstructure of frozen noodle were studied systematically inthis paper，the mechanism of different frozen conditions affecting frozen noodles quality was alsodiscussed, the research contents were described as follows:(1)the increace of frozen storage time,temperature fluctuation amplitude and frequency all madehanrdness of noodles decreased significantly,resilience had increased,other textural properties did notchange significantly.The influence of tensile and shear properties of frozen noodles affected by differentfrozen condition was more complex.(2)With the increace of storage time,tempetature fluctuation amplitude and frequency,dry substance lossrate increased,Protein loss rate was not obvious.Noodle breaking rate,dry substance loss rate and proteinloss rate increased significantly when refrigerated was longer than20d and temperature amplitude was±5℃.(3)Noodles luminance value(L*) decreased and yellowness value(b*) increased with the extension offrozen time,the increasing of temperature fluctuation frequency and amplitude,the value of redness (a*)hadno significant change.With the calculation of△E(abemation),when storage days were longer than20d andthe temperature fluctuation were±5℃,the color of the noodles became darker and more yellowobviously.But the color did not appear significantly different with the increasing of temperature fluctuationfrequency.(4)Through the determination of the amount of noodles protein extraction after refrigeration,the extraton ofthe albumin and globulin showed an increasing trend in different refrigeration mode,but the change wasnot significant.The extraction of Gliadin,glutenin and GMP transformed into each other regularly with theincreasing of refrigeration time,temperature fluctuation frequency and amplitude.(5)The pentosan content was determined by Duffau distillation,the result showed that:refrigeration modehad no signigicant affection on pentosan content,but pentosan content decreased after15d.(6)The starch component was determined using the colorimetric method,the result showed that:fastdigestible starch content decreased slowly,resisitant starch and slowly digestible starch content showed a slow upward trend.Little effection on resistant starch with the increasing of temperature fluctuationfrequency and amplitude,but fast digestible starch showed an downward trend and slowly digestible starchshowed a converse trend in these modes.(7)The disulfide bond of Protein and GMP,the secondary struture of the protein,noodles microstructurewere studied by Ellman’s colorimetric method,Fourier transform infrared spectroscopy and scanningelectron microscope.The results showed that:protein disulfide content showed a decreasing trend and GMPdisulfide content showed an upward trend after refrigeration.The proportion of disulfide bond in totalsulfhydryl of GMP was higher than that in protein.(8)The α-helix content in protein secondary structure decreased and the random coil content graduallyincreased with the increasing of refrigeration time,temperature fluctuation amplitude and frequency.Thecontent of β-turn tended to increase with the increasing of refrigeration time and temperature fluctuationamplituede,but it increased first and then decreased with the increasing of temperature fluctuationfrequency.(9)The microstrucure of noodles after different frozen modes was observed with scanning electronmicroscope,the observation showed that:after different modes of refrigeration,the gluten net were damagedwith different degrees,the gluten net became loose and the starch molecules combined again...