| Meatballs are a kind of meat products that people usually consumed.It usually takes animal meat,poultry or fish as the main raw material,and is supplemented by starch,vegetables,seasoning and other mixed processing.Because of its special taste and flavor,it has been deeply loved by consumers.However,with the improvement of people’s health awareness,the traditional meatballs has been unable to satisfy people’s needs for low-fat diet and balanced nutrition because it contains more fat and simple nutrition.Therefore,it is an irresistible trend to add nutritionally rich fruits and vegetables to the meatballs while reducing the fat content of the meatballs.Purple sweet potato has always been a research hotspot in the food industry because it contains a variety of bioactive substances.At present,more scholars have conducted in-depth studies on the development and utilization of purple sweet potato,but the research direction is mainly focused on the development of beverages,dairy products,flour products and baked products,but there are few reports on the application of purple sweet potato in meat products,and lack of in-depth studies on the effects of purple sweet potato on the quality of meatballs.In addition,reducing the fat content in the meatballs will have an adverse effect on the flavor and texture of the meatballs.Some studies have shown that using appropriate fat substitutes to replace the fat in the meatballs can effectively improve the quality of the meatballs.In view of this,this study by using whole purple sweet potato powder(WPSPP)to replace the cassava starch in traditional pork meatballs,and sodium alginate(SA)or konjac glucomannan(KGM)gels is used as a fat substitute to analyze and detect the edible quality,flavor substances,digestive characteristics and quality changes of meatballs during storage.The main findings are as follows.1.Effect of the supplemental amount of purple sweet potato powder on the edible quality of pork meatballs.WPSPP replaced 25%,50%,75% of tapioca starch in meatballs(that is,5%,10%,and 15% of WPSPP addition)was used as the experimental group,and meatballs without WPSPP were used as the control group.With the increase of WPSPP content,the types and total amount of volatile flavor substances such as alcohols,aldehydes,ketones and esters in meatballs increased,while the hardness,cohesion,masticability and brightness of meatballs decreased significantly,while the elasticity and cooking loss rate did not change significantly.When WPSPP content were 5% and 15%,the freeze-thaw water separation rate of meatballs decreased by about 7%.When WPSPP content were 5%,10% and 15%,anthocyanin content in meatballs could be increased by 0.10 mg/g,0.15 mg/g and 0.24 mg/g,respectively.And dietary fiber could be increased by 0.852 g/100 g,1.064 g/100 g and 2.326 g/100 g,respectively.When the WPSPP content was 5%,the sensory score of meatballs was the highest.When the WPSPP content was 15%,the texture and taste of meatballs became worse,and the edible quality was not good.2.Effects of different fat substitutes on edible quality and digestive characteristics of purple sweet potato meatballs.3%,6% and 9% SA gels and 2%,4% and 6% KGM gels were used as fat substitutes to replace 50% fat in purple sweet potato meatballs,and 10%WPSPP without fat substitutes were used as full-fat control group.The decrease of fat content will make the sensory quality of purple potato meatballs worse.SA gels or KGM gels as fat substitute can improve the taste of purple sweet potato meatballs.The hardness and chewability of purple sweet potato meatballs decreased significantly with the increase of SA gels concentration,but increased with the increase of KGM gels concentration.The elasticity of purple sweet potato meatballs had no significant change.When the SA gels concentration was 3% or KGM gels concentration was 6%,the texture quality of purple sweet potato meatballs was close to the control group.When the SA gels concentration was 9%,the total juice yield and cooking loss rate of purple sweet potato meatballs decreased by 89% and 30%,respectively.When the SA gels concentration was 6%,the freeze-thaw water separation rate of purple sweet potato meatballs decreased by about 34%.When the concentration of KGM gels was 2%,the total juice yield,cooking loss rate and freeze-thaw water extraction rate of purple potato meatballs could be reduced by 80%,29% and 80%,respectively.SA or KGM could change the volatile flavor composition of purple sweet potato meatballs,and had no adverse effect on the volatile flavor of purple sweet potato meatballs.In the simulation of in vitro digestion,SA or KGM gels with different concentrations could significantly reduce the digestibility of fat,but had no significant effect on the dissolution rate of anthocyanin.The starch hydrolysis rate of the meatballs in 9%SA and 4%KGM groups was the lowest,which decreased by 10.30% and 8.14%,respectively,compared with the control group.With the increase of SA gels concentration,the protein digestibility of purple sweet potato meatballs in vitro decreased gradually,and KGM had no significant effect on the protein digestibility.3.Influence of different storage time on KGM low fat purple potato meatballsFirstly,KGM gels with different concentrations(2%,4%,6%)and different fat content substitution degree(25%,50%,75%)were optimized by weight method,and the optimal formula(KGM6-50)was obtained by using 6% KGM gels as fat substitute to replace 50% fat in purple sweet potato meatballs,and the quality changes during storage at-18 ℃ were analyzed.Compared with the non-WPSPP group,the freezing-thawing water separation rate of samples from KGM6-50 group during storage was significantly decreased,the degradation rate of texture and quality was slower,and p H and cooking loss rate were not significantly changed.Compared with the full-fat control meatballs supplemented with WPSPP,the freeze-thaw water extraction rate of samples in KGM6-50 group was slightly increased,and the cooking loss rate was significantly decreased.The addition of WPSPP can make the peroxide value of meatballs increase faster in the storage process.When the storage time is less than 30 days,the peroxide value of meatballs is low,and other quality changes are small,which is the best edible period. |
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