Effect Of Waxy Wheat Flour On The Quality Of Frozen Dumplings

Waxy wheat flour has high amylopectin content, which endows it unique starchproperties, with low setback and good freeze-thaw stability. This can be widely used in chilledand frozen foods. Therefore, blending wheat flour with waxy wheat flour in frozen dumplingscan provide a new idea for the quality improvement of frozen dumplings. Application ofblends in frozen dumplings is important for development of new products and making use ofwaxy wheat flour in food processing areas.Firstly, the physicochemical properties of waxy wheat starch (WWS) and wheat starchwere studied. Compared with wheat starch, WWS had low amylose content and smallerparticle size. Waxy wheat starch started to swell at low pasting temperature with highviscosity and low setback. WWS had a higher water retention capacity at differenttemperature. WWS exhibited greater freeze-thaw stability and a lower hardness starch gelcompared with wheat starch. Waxy wheat starch was belonged to type-A high crystallinestarch with high crystallinity.Secondly, properties of pasting, thermal, rheological and textual characteristics of blendswere investigated. It showed that addition of waxy flour decreased the setback, pastingtemperature and gelatinization enthalpy. Replacement of waxy flour could significantlyincrease water absorption from62.23%to64.57%, but did decrease the development time ofdough and dough stability time (from2.80min,9.80min to1.87min,5.70min). With theincrease of waxy flour, the gel hardness significantly decreased from130.806g to23.995g,but cohesiveness and resilience were increased.Thirdly, the changes of mixed gels in syneresis, rheological properties, gel hardness andmicrostructure were investigated to explore the effect of WWS on freeze-thaw stability ofstarch gels. Results showed that WWS significantly reduced the syneresis and hardness ofgels, and WWS inhibited the increase. Compared with nonwaxy wheat starch, mixedgelatinized gels displayed less changes in storage shear modulus G’ and loss shear modulusG’’ during the freezing and thawing cycles than starch gels without WWS. Scanning electronmicrograghs of freeze-thaw gels showed that smaller pore size and a thinner surroundingmatrix corresponded with increasing WWS addition. With the increase of freeze-thaw cycles,the gel structure was destroyed less and remained stable.Then, DSC and SEM were used to study the effect of waxy wheat flour on frozen watercontent and microstructure of dough. DSC analysis showed waxy wheat flour significantlyreduced the content of frozen water. The micrographs of the freeze-thawed gels revealed thegluten structure deteriorated and starch exposed outside the network with the addition of waxy wheat flour. This may be associated with the poor property of gluten protein. It can beshowed by measuring analysis that, adding waxy wheat flour increased free thiol group duringfreezing and thawing and disulfide bonds in dough disconnected.Finally, the influence of different amounts of waxy wheat flour on textural properties andsensory characteristics of dumplings were discussed in the paper. With the amount of waxywheat flour from0%to30%, cooking time and cooking loss rate of dumpling skinsignificantly decreased, but the toughness and gumminess of dumpling skin increased.Cracking rate and sensory score increased significantly, thus improved the eating quality ofdumplings. Moreover, with the increase of freeze-thaw cycles, waxy wheat flour is effectivein preserving quality in frozen product and improving the food value. The optimum dosagewas20%.Comparative effects of20%waxy wheat flour and xanthan gum, monoglycerides on thequality of frozen dumplings were studied. With20%waxy wheat flour, xanthan gum andmonoglyceride respectively, cooking loss and cracking rate of dumpling skin weresignificantly reduced, and dumplings with20%waxy flour showed the most obvious effect.During the freezing and thawing cycles, the toughness of dumpling skin was significantlyincreased, but toughness of dumpling skin with waxy wheat flour and monoglycerideincreased more significantly.