Comparative study on effect of pectin, gelatin and modified starch replacement with fish gelatin in textural properties and graininess of Non-fat yogurt

This study aimed to evaluate the quality of set style yogurt with replacing skim milk powder with high bloom gelatin (HBG), low bloom gelatin (LBG), cold water fish skin gelatin (FSG), low methoxyl pectin (LMP) and modified tapioca starch (MS), and effect of these thickeners on textural and physicochemical properties of samples. Firmness is one of the major sensory attributed important to customer preference. Because of low total dry material (9%) of raw milk lower concentration of thickeners didn't have suitable effect on textural properties of samples, higher value of textural parameter related to firmness and fracturability was found in samples contained 1% HBG. Viscosity of samples increases with addition of thickeners and have a straight relationship with stabilizer concentration and viscosity, in HBG contend samples slope of viscosity vs. concentration curve was highest and maximum viscosity obtained with 1% HBG addition. Except pectin all samples pH decreased over time, but MS significantly increased acidification process. All kinds of, gelatins and modified starch decrease synersis, but a reverse correlation between pectin concentration and synersis. Also all of types of gelatin decreased number of grains and grain perimeter but starch significantly increased graininess in all concentrations (p<0.05). Graininess trend in samples contained LMP decreased up to 0.05% but, higher concentration of LMP lead to more graininess. However FSG showed the best effect on decreasing of graininess.

Keywords:

textural properties , Non-fat yogurts , replacement , Gelatin , pectin , modified starch