Study On Changes Of Stale Of Water And Quality Ndex In Quick-frozen Dumplings Flour Under Low Temperature Conditions

Taking quick-frozen rice dumplings flour as the research object,studied the effects of food additives on the water-holding capacity of quick-frozen rice dumplings flour using the Low-field NMR; Effect of frozen storage time and frozen temperature on the spin-spin relaxation character and the index of quality, the correlation between the state of water and the quality of quick-frozen rice dumplings flour was studied; By imitating the temperature fluctuation and the cold chain interruption on the state of water and the quality of quick-frozen rice dumplings flour, we were looking forward to providing the quality change of quick-frozen rice dumplings stored under lower temperature condition with theory foundation. Water plays an important role in quick-frozen rice dumplings, water turn into ice and recrystallization in the quick frozen and frozen storage, along with the change of the state of water, it would has effects on the quality of quick-frozen rice dumplings.In order to study the water-holding capacity of quick-frozen rice dumplings flour, the spin-spin relaxation character measurement in quick-frozen rice dumplings flour was carried out by CPMG (Carr-Purcell-Meiboom-Gill) pulse sequence using the Low-field NMR. The results showed that:It is feasible that using Low-field NMR researched on the water-holding capacity of quick-frozen rice dumplings flour, and the optimal addition amounts was investigated by response surface methodology to be0.2%sodium tripolyphosphate,0.19%xanthan gum and0.23%monoglyceride, the water-holding capacity of quick-frozen rice dumplings flour prepared under these optimal conditions is the best.Effect of frozen storage time and frozen temperature on the spin-spin relaxation character and the index of quality of quick-frozen rice dumplings. Quick-frozen rice dumplings were frozen then stored at-10℃、-18℃、-25℃for up to12weeks. NMR results showed two populations of water:water strongly bound to macromolecules(T21) and more mobile water. As storage time increased, and concomitant with an increase in the T21, the relaxation times were found to decrease with decreasing temperature. Different frozen storage temperature had no significant influence on the TPA parameters, the hardness, gumminess and chewiness increased with storage time. The correlation analysis results showed good correlations between the relaxation parameters T21, A21, A22and the index of quality. Quick-frozen rice dumplings firming results from redistribution of water, therefore, the state of water allows reflection of the hardness degree.Effects of temperature fluctuation on the quick-frozen dumplings at-18℃constant temperature storage were studied. The state of water, Sense scores, the moisture content and the TPA parameters were measured as quality parameters. Temperature fluctuations during storage accelerated deterioration in quick-frozen dumplings. Large temperature fluctuations during frozen storage resulted in significantly more loss of quick-frozen dumplings quality than storage at constant temperature.The cold chain was interrupted when the quick-frozen rice dumplings were transported, the result show that as the frequency and time of the cold chain interruption increased, it had no significant influence on the TPA parameters:the hardness, gumminess and chewiness, the relaxation parameters T21, T22, A21, A22had no significant change.