EFFECT OF AGE-RELATED GASTROINTESTINAL ALTERATIONS ON PROTEIN HYDROLYSIS DURING IN VITRO DIGESTION OF HIGH-PROTEIN YOGURT

The consumption of products that provide a high protein intake is one of the main nutritional recommendations for older adults since adequate protein intake is essential to prevent sarcopenia, a progressive loss of muscle mass associated with aging. Thus, high-protein yogurts are interesting products to this age group, due to its content of high biological value proteins. However, the aging process leads to several changes in the human body, including a decline of certain gastrointestinal functions. Thus, it is important to understand the digestibility of these products considering elderly gastrointestinal conditions. This study aimed to evaluate the effect of common age-related gastrointestinal alterations on protein hydrolysis during the in vitro digestion simulation. High-protein yogurt was produced through the dispersion of a mixture of whole milk powder and calcium caseinate in water. The mixture was kept at 4°C overnight, homogenized (150 MPa + 50 MPa) and heat-treated (85°C/30min). Then, the mixture was fermented with lactic culture consisting of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus at 45°C. The yogurts were submitted to the in vitro gastrointestinal digestion in conditions that simulate the digestion of adults and older adults, according to the INFOGEST protocols. The protein hydrolysis during the digestion conditions was evaluated by quantifying 12% TCA (12% TCA-SN) soluble nitrogen in yogurts and digests. The digestion led to an increase in the 12% TCA-SN in relation to total nitrogen content [12% TCA-SN (%TN)]. Yogurts presented 4,54% of 12% TCA-SN (%TN) while adult and older adult digests presented 95,56% and 88,53% of 12% TCA-SN (%TN), respectively. Thus, the results suggested that age-related gastrointestinal conditions impaired protein hydrolysis during high-protein yogurt simulated digestion.