Effect Of Polydextrose On Quality Of Set-style Yoghurt And Research In Various Parameters During Storage

Polydextrose has often been used as a functional food additives because ofprebiotic effects. Benefits of polydextrose are mainly reflected in the followingtwo-fold: to promote the growth of beneficial bacteria in the body and stimulateimmune system. Also, polydextrose has the advantages of substitute of fat and lowcalorie. When used as fat substitute, it can bring the product fat-like taste and texture.Therefore, polydextrose as raw materials in production of yoghurt with skimmed milkpowder because that it can be as fat substitute additives. Stability of polydextrose inset-style yoghurt was studied. Polydextrose set-style yoghurt production technologywas optimized and effects of polydextrose on sensory evaluation, physico-chemicalproperties and flavor substances of polydextrose set-style yoghurt and ordinaryyoghurt were analyzed. Findings are as follows.(1) Stability of polydextrose in set-style yoghurt was analyzed. According topreservation rate of polydextrose set-style yoghurt. Preservation rate of polydextroseremained between70%to76%after changing its fermentation and ripe conditions. Itis suggested stability of polydextrose in set-style yoghurt is good and it can play a roleof substituting fat.(2) On the basis of single-factor experiments, appropriate level of fermentationfactors were determined according to sensory evaluation of various samples. Contentof skimming milk power and content of polydextrose and fermentation time wereoptimized by the response surface optimization experiment. The optimal parameterswere shown as follows: fermentation temperature was42℃, sugar amounts was7%,inoculation numbers was3%, the content of skimming milk powder was11%, contentof polydextrose was4%, fermentation time was3.5h. The yogurt had smoothstructure, good taste and excellent flavor.(3) The flavor components polydextrose set-style yoghurt and ordinary yoghurtwere analyzed by headspace solid-phase micro-extraction coupled with gaschromatography-mass spectrometry. The kinds of flavor components detected in thetwo samples were nearly the same. Aldehydes, ketones, acids, esters, aromaticcompounds, terpenoid compounds, alcohols were existed in both ordinary yoghurt and polydextrose set-style yoghurt.Due to the partial hydrolysis of polydextrose can yield short chain fatty acids andpromote growth and reproduction of Lactobacillus, contents of acids and esters inpolydextrose yoghurt are higher than ordinary yoghurt while content of ketones ofordinary yogurt are lower. This is due to contents of acids, aldehydes, alcohols,aromatic substances in polydextrose yoghurt are higher than ordinary yoghurt, whichlead to lower content of ketone substance.(4) Sensory evaluation, physico-chemical properties and flavor substances ofpolydextrose set-style yoghurt and ordinary yoghurt was analyzed at storage of4℃.Variation regularity of sensory evaluation, physico-chemical properties and flavorsubstances of polydextrose set-style yoghurt and ordinary yoghurt and effects ofpolydextrose on sensory evaluation, physico-chemical properties and flavorsubstances were investigated. Through data analysis, correlations between the variousindicators of polydextrose and ordinary yogurt were obtained and have a positive rolein the theory and practice.Analysis shows that polydextrose can improve sensory evaluation,physico-chemical properties and flavor substances of yoghurt during storage.Correlations between the various indicators of polydextrose yoghurt were higher thanthat of ordinary yoghurt, which suggested that polydextrose can prolong shelf life ofset-style yoghurt.