The effect of high‐polyphenol sumac (Rhus coriaria) on food intake using sensory and appetite analysis in younger and older adults: A randomized controlled trial

Aging is accompanied by a decline in appetite and food intake with associated deficiencies in both macronutrients and micronutrients. The aim of this study was to investigate the impact of adding Iranian brown sumac (Rhus coriaria) (CIBS) into butternut squash soup on sensory evaluation and food intake among older adults (n = 20; >65 years old) and younger adults (n = 20; 18–35 years old). To evaluate the polyphenol content and antioxidant activity of the sumac samples, a Folin–Ciocalteu assay (FCR) and ferric ion reducing antioxidant power (FRAP) assay were used, respectively. L‐glutamic acid was assessed using a Megazyme L‐glutamic acid assay. Compusense software was used to assess the sensory evaluation attributes of free‐living older adults and younger adults receiving different doses of sumac in butternut squash soup. Nutritics software was used to assess food intake following the addition of 0.37 g of sumac to soup. CIBS was selected based on a preliminary assessment in vitro for L‐glutamic acid, antioxidant, and polyphenol content of six varieties of sumac. Sensory evaluation results revealed that the difference in perceived intensity of brown color between the soup samples with different doses of CIBS was greater in the younger adults' group (p = .001) than in older adults (p = .037). In addition, the food intake study found that during the ad libitum lunch, older adults consumed more energy (kcal; p = .014), protein (g; p = .025), carbohydrate (g; p = .013), and fat (g; p = .002) after soup with sumac compared to control soup. The overall findings of this study suggest that the addition of sumac to food may have a potential benefit in enhancing ad libitum lunch intake in older adults leading to effective management of malnutrition. This may promote healthy aging and minimize the burden and the consequences of anorexia of aging as main public health concerns.