Product development and sensory analysis in terms of healthy nutrition: Trial of kefir enriched with tryptophan amino acid

In today's world, individuals have increasingly begun to alter their dietary habits and adopt new nutritional trends in pursuit of healthier lifestyles. Scientific studies have demonstrated that certain food components can influence the central nervous system, affecting factors such as depression, anxiety, sleep, and appetite. In this context, the amino acid tryptophan stands out due to its pivotal role in these physiological processes. Kefir, known for its probiotic content, is a fermented dairy product that supports gut health. The aim of this study is to develop a tryptophan-enriched kefir by incorporating chia and flax seeds, which are naturally rich in tryptophan. Within the framework of quantitative research methods, product development and sensory analyses were conducted, alongside chemical analysis to determine the tryptophan content. Two kefir samples were developed (206: strawberry and banana; 208: blueberry and honey) and subjected to two-stage sensory evaluations by trained panelists and consumers. The products were assessed based on appearance, texture, aroma, taste, and overall acceptability. For the quality rating test, a 7-point Likert scale (1 = strongly disliked, 7 = strongly liked) was used, while a 5-point Likert scale (1 = very poor, 5 = very good) was employed for the consumer preference test. According to the results of the sensory analysis conducted by trained panelists, both samples received scores above average (>3.5) for all criteria except fruit aroma. Consequently, both samples were included in the consumer preference test and were again rated above average (>2.5), indicating consumer acceptance. The tryptophan content of the developed products was determined to be 46 mg per 100 grams, which is close to the tryptophan level found in plain kefir. This slight reduction is thought to be influenced by factors such as the low pH levels and oxidation potential of the added fruits used for flavor and color enhancement. In light of these findings, it is recommended that the chemical properties of fruits be considered in product formulation. These enriched kefir products have the potential to contribute to healthier dietary choices and may serve as a foundational model for future innovations in functional dairy products.