Course:VANT149/2025/Capstone/Science/Team23

Abstract

This study explored the pH changes as a proxy for bacterial growth of homemade and store-bought yogurt for 23 days. In homemade yogurts, especially flavoured varieties, an initial rise in pH was followed by stabilization under refrigeration, indicating early bacterial activity before reaching equilibrium. Plain and lemon-flavoured homemade yogurts showed more stable pH levels, suggesting a balanced microbial environment. Store-bought yogurt maintained a steady pH around 4.5, which is slightly more acidic compared to homemade yogurt, reflecting the effectiveness of preservatives and stabilizers. Unrefrigerated samples, regardless of whether they were homemade or store-bought, exhibited rapid acidification and visible mould growth by day 6, linked to accelerated fermentation and spoilage fungi. These findings underscore the importance of proper storage and formulation in maintaining the safety, quality, and appeal of yogurt products.

Keywords: N/A

Biographies

Person 1

Vitor Han is a first-year student in Vantage One Science at the University of British Columbia. He is planning to study Computer Science in future years. His research focuses on pH changes and microbial spoilage in various yogurt types under different storage conditions. He is interested in this topic because of its implications for food safety and shelf life, and he looks forward to learning more about microbiological preservation methods at the conference.

Person 2

Hajar Alnabilsi is a first-year Science student at the University of British Columbia, with plans to pursue a major in Biology next year. Her research focuses on comparing pH changes in plain, flavoured, and commercial yogurt during storage to better understand how ingredients and processing methods affect acidity over time. She is personally interested in this topic because of its relevance to food safety and everyday consumer choices.

Person 3

Tahira Khalili is a first-year science student at the University of British Columbia with a strong interest in health and wellness, aiming to study COGS (Cognitive Systems). Her research focuses on how pH levels fluctuate in plain, flavoured, and store-bought yogurt during storage. She chose this topic because of its connection to health and food safety, and her desire to better understand how everyday products can impact well-being.