Tehran University of Medical Sciences Journal of Nutritional Sciences and Dietetics 4 2 2018 04 30 220 220 EN Samira Yeganehzad Department of Food Processing, Research Institute of Food Science and Technology, Mashhad, Iran Abolfazl Pahlevanloo Department of Food Processing, Research Institute of Food Science and Technology, Mashhad, Iran Maryam Kiumarsi Department of Food Processing, Research Institute of Food Science and Technology, Mashhad, Iran Azadeh Zayerzadeh Doctorate of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran Seyed-Alireza Sadjadi Psychiatry and Behavioral Sciences Research Center, Ibn-e-Sina Hospital, Mashhad University of Medical Sciences, Mashhad, Iran Mostafa Shahidi Department of Food Processing, Research Institute of Food Science and Technology, Mashhad, Iran Narjes Nadali Department of Food Processing, Research Institute of Food Science and Technology, Mashhad, Iran 2018 04 22 2018 07 27 Objective: Some food-derived bioactive peptides have demonstrated positive effects on stress reduction. This study was an attempt to evaluate the effectiveness of daily consumption of 12 g of sugar-free chocolate containing 150 mg of αs1-casein (91-100) peptide in alleviating stress in healthy, normal-weight participants. Methods: Salivary cortisol concentration and self-report questionnaire data were obtained before and after chocolate consumption. Sixty participants completed the Cattle Anxiety Scale (CSI), the Beck Depression Inventory (BDI), and the Depression Anxiety Stress Scales 21 (DASS-21). Results: Results from the CAS and DASS-21 questionnaires showed that consumption of chocolate containing bioactive peptide reduced anxiety and stress (p < 0.05). Salivary cortisol measurement showed more than 30% reduction in cortisol level in the intervention group. The peptide had a 95% recovery rate and also demonstrated  thermal and mechanical stability during the production process. Conclusion: Findings confirmed the undenatured structure of the αs1-casein peptide in chocolate and its resistance to the chocolate processing condition. https://jnsd.tums.ac.ir/index.php/jnsd/article/view/220 https://jnsd.tums.ac.ir/index.php/jnsd/article/download/220/204