Effects Of Freezing And Maillard Reaction On Quality Of Black Garlic

As a new kind of garlic refined product,black garlic has a healthy function and the taste and functional value is greatly improved.Maillard reaction was the main reason for the browning of black garlic.Therefore,the study of Maillard reaction in the processing of black garlic was of great significance in studying the browning mechanism of black garlic.In this study,fresh garlic was used as raw material,then pre-freezed and vacuum packaged,and put it in heat storage.Modern instrumental analysis was used to study water distribution,texture,aromatic flavor,reducing sugar and sensory changes in Maillard reaction of black garlic.The effects of Maillard reaction to the products of black garlic were investigated.The main results were as follows:1.The results of low field nuclear magnetic resonance?LF-NMR?and TPA analysis showed that the water activity of frozen garlic increased,relative content of free water increased and T₂ value increased,the proton density increased,and the water molecular binding strength increased.The water activity of garlic which has had Maillard reaction decreased,free water decreased sharply.With the increase of Maillard reaction's time,T22proton density and relaxation time decreased.The relaxation time of T21 was decreased,and the water was more closely bound.The higher the temperature of Maillard reaction was,the stronger the combination of water molecules.Frozen processed garlic firmness decreased rapidly,elasticity reduced,cohesiveness weak,with the decrease of temperature,the hardness of garlic decreased more quickly;with the Maillard reaction going on,garlic's hardness rose,elasticity increased,cohesiveness increased,adhesiveness increased,the higher the Maillard reaction's temperature,the faster the hardness rose.2.The results of head space solid-phase microextraction GC-MS method showed that the content of volatile flavor substances of garlic after freezing increased,the irritating sulfur-containing compounds decreased,the content of allicin decreased;after Maillard reaction,the variety of volatile aromatic substances in garlic increased.The content of diallyl disulfide was significantly reduced in black garlic.The content of diallyl sulfide in aroma flavor compounds increased by 20%.With the increase of reaction time,the composition of aromatic substances increases.The higher the reaction temperature,the higher the furan content.3.The results of colorimeter and DNS showed that the degree of browning of frozen garlic increased with the decreasing temperature.The lower the freezing temperature,the higher the value of browning and the faster the Maillard reaction.With the increase of Maillard reaction's time,garlic's browning degree increased.The higher the reaction temperature,the faster the browning rate;the frozen reducing sugar content was higher,and the lower the temperature,the higher the reducing sugar content.the higher the Maillard reaction's temperature,the faster the reducing sugar changed.The longer the time,the more pronounced changes in reducing sugars.4.Taking the content of reducing sugar as the index,to study the effect of freeezingtemperature,Maillard reaction's time and temperature on reducing sugar of black garlic by response surface analysis.The optimum technological conditions for obtaining black garlic are as follows:freezing temperature-21?,under the condition of 70?for 20days,the content of reducing sugar in black garlic was the highest.5.The sensory evaluation results showed that frozen garlic has more sweet taste and better taste,the lower the freezing temperature,the higher the sweetness,if the Maillard reaction's temperature was higher,the changes of garlic's appearance was more obvious,volume reduced.In the early period,garlic was soft and sticky,in the late period,hardness of garlic increased,and garlic became bouncy and not sticky.