Investigation of the effect of pectins of fruit and vegetable powders on the technological properties of confectionery glaze

Fruit and vegetable raw materials and processed products contain dietary fibers and biologically active substances, so the use of such raw materials in the manufacture of foods increases their nutritional value. In addition, dietary fibers of fruit and vegetable raw materials can influence the technological properties of food systems. The purpose of this work is determination of the amount of dietary fibers, pectins and the degree of their esterification in fruit and vegetable powders, as well as establishment of an impact of these parameters on the technological properties of confectionery glazes with the addition of fruit and vegetable powders (taking into account the ability of the latter to absorb fat). Objects of research are powders of carrots, apples, beets, raspberries and model samples of confectionery glazes with their addition. Rheological parameters of confectionery glazes were determined by the Casson method on a rotary viscometer. The content of dietary fibers was established by the enzymatic-gravimetric method. Pectins from powders were isolated by acid hydrolysis of raw materials followed by ethanol precipitation. A degree of esterification of pectins was calculated on the basis of the results obtained by potentiometric titration. It has been found that the studied fruit and vegetable powders from domestic raw materials were characterized by a high amount of dietary fibers (24–38%), the main part of which was represented by pectin. Beet and raspberry powders contained low esterified pectins (18 and 33 g/100 g); apple and carrot powders contained highly esterified pectins (16 and 27 g/100 g). Powders with low esterified pectins showed a moderate increase in the Casson yield strength of the glazes with their addition that did not exceed the optimal values of this indicator. With increasing concentrations of powders with highly esterified pectins, a sharp increase in the Casson yield strength of the glazes was observed. At concentrations of 13% and more, this indicator exceeded the optimal values. Thus, in the development of confectionery glazes with fruit and vegetable powders, prediction of their maximum concentration can be carried out by determining the content of dietary fibers, pectins and a degree of their esterification, as well as by taking into account pH and the ability of powders to absorb fat.