Enhancing Nutritional Value of Rhubarb ( Rheum rhaponticum L.) Products: The Role of Fruit and Vegetable Pomace

In this study, the quality and health-promoting components in rhubarb products sweetened with isomaltulose and enriched with fruit (apple, chokeberry, black currant) and vegetable (beetroot, carrot) pomace were assessed. All products with added pomace had higher levels of ash (27–65%) and macro- and microelements (5–436% and 5–333%) compared to the sample without pomace. The addition of pomace also increased the total antioxidant activity. The addition of pomace increased the value of gel strength (Fe) by 22–73% compared to the control; the highest value was found in the product enriched with chokeberry pomace (1.71 N). Red ( a * > 0) and yellow ( b * > 0) dominated all products, and values of the L * parameter ranged from 7.81 to 37.54. The brightest were the products with added carrot, apple, and beet pomace, while the darkest were those containing chokeberry and blackcurrant pomace. The values of the texture parameters decreased after storage, but to a lesser extent in the products with pomace; however, the products with pomace maintained greater antioxidant activity and retained beneficial components better than those without. A slight darkening of the products and a decrease in the proportion of red ( a *) and yellow ( b *) color was also observed.