Study On The Development And Rheological Properties Of Low-sugar Huangguan Pear Jam

Jam is one of the favorite foods of consumers.Huangguan pears are rich in nutrients and have less stone cells.They mature in mid-August every year and go on the market in large quantities.If the storage period is too long,it will easily lead to a large loss of nutrients in the pears,which can be processed.The jam is good for improving the utilization rate of huangguan pears to reduce economic loss.The effects of different kinds of sugar,acid and thickener in jam on the rheological properties and flavor of huangguan pears were studied in this paper.We used by rheometer and electronic nose.to select suitable ingredients for the huangguan pear jam.We had explored the softening methods for huangguan pear jam quality.We had analyzed the influence of beating time on pear jam with rheological characteristics,color difference,soluble solid content,volatile matter and other indicators.We had compared the concentration and cooling methods in jam processing to analyze the rheological characteristics,ascorbic acid content and titratable acid content changes of jam.The following conclusions were obtained:1.The yield stress and viscosity of huangguan pear jam with inulin were significantly higher than those with other sugar.The highest composite viscosity of jam with inulin.Citric acid was conducive to the formation of stable gel structure of huangguan pear jam.The rheological properties of jam with citric acid were the lowest.The jam with thickener can achieve thickening effect.Compared with non-thickening jam,the resistance and plasticity of jam with microcrystalline cellulose were significantly improved,followed by jam with soybean dietary fiber.2.The yield stress and viscosity of the jam softened by blanching were the highest.Blanching treatment,steam treatment and microwave treatment can protect the color of huangguan pear jam.Among them,the jam treated by blanching can keep the volatile compounds better.The content of ascorbic acid in blanched jam was lower than the unharded jam.The hot steam processed jam lost more ascorbic acid.The jam after microwave treatment had relatively high water content.3.We had compared the jams made with different beating times: The longer the beating time,the smaller the particles of the pear tissue will be broken.It was found that the processed jam was the best quality when beating for 90 s.The jam gel structure after 90 s beating was relatively stable,and the yield stress and viscosity value of jam were relatively large.The flavor of jam can be well preserved,and the volatile compounds were rich and strong.The contents of soluble solid and soluble protein in jam were relatively high.The brightness value of 90 s beating jam was higher than that of 120 s beating jam and 150 s beating jam.4.From the way of concentration and cooling: The water content of the jam concentrated by 2100 W was the least,the soluble solid content was the highest,the titratable acid content of the jam was significantly higher than that of the jam concentrated by other methods,the jam was not easy to flow,and had high hardness and strong cohesion.The browning degree and ascorbic acid loss of 300 W concentrated jam were the least.From the perspective of rheological properties,the progressively cooled jam was less fluidity.In summary,20% inulin,0.2% citric acid and 0.6% soybean dietary fiber were added to the jam to obtain green,healthy and good rheological properties of low sugar huangguan pear jam.In the process of softening,the water content of the jam was significantly reduced by blanching,and the flavor of the jam was similar to that of the unsoftened treatment,but the ascorbic acid content decreased significantly.After beating huangguan pear for 90 s,the structure of the jam was stable and nutritious,but the color and brightness of the jam became dark.At 2100 W,the hardness,cohesiveness and water content of concentrated jam were the highest,and the loss of ascorbic acid was more.The cooling mode was little effect on jam,among which the fluidity of the sauce cooled by stages was the smallest,and the color of cold cooling jam was the brightest.