Optimization of Traditional Cow's Milk Cheese Production Using a Combination of a Starter Culture and a Plant-based Coagulant (Solanum dubium)

Abstract

Background: Traditional local cheese (Djibna baida) production relies on spontaneous milk acidification and plant-based coagulation. Aims: The study aims to optimise the traditional cheese-making process through the combined use of starter cultures isolated from local cheeses (Djibna baida) and a coagulant extracted from the fruits of Solanum dubium Study Design:  Descriptive study based on technological processes, characterisation tests, and interpretation of results. Place and Duration of Study: This was an experimental study conducted at the Food Science and Nutrition Research Laboratory (LaRSAN) of the Faculty of Human Health Sciences at the University of N’Djamena. The production of the experimental cheese and the associated analyses were carried out over a three-month period, from May 15 to August 13, 2024. Methodology: A crude Jibbên extract was prepared by macerating dried fruit powder. The viability of a starter culture composed of Lactococcus and Leuconostoc strains was assessed using the reductase test. Two types of cheese were produced: a control cheese (traditional method) and an experimental cheese (EC). The EC process involved pasteurisation at 63°C, inoculation with 3.5% starter culture, a 4-hour ripening period, and the addition of 1.2 ml/L of Jibbên extract, salt, garlic, and black cumin. Technological parameters, pH kinetics, and sensory quality (assessed by a panel of 10 tasters) were compared after 15 days of storage at 4°C. The data were processed using Excel 2019 and SPSS Statistics 25 software. Results: The results showed that the maximum acidification kinetics reached 81°D after 16 hours of incubation, with a reduction time of 27 minutes. Microbiological analysis results for the crude Jibben extract showed low microbial loads, with a total aerobic mesophilic flora count of 2.03 × 10³ CFU/g and a yeast and mould count of 3.16 × 10¹ CFU/g. The shortest flocculation time was recorded for control cheese FC1 (35.28 minutes), followed by control cheese FC2 (39.83 minutes). In contrast, for the reference cheeses (FT1 and FT2), the formation of the initial curd was observed after 47.58 minutes and 69.14 minutes, respectively. The optimal coagulant dosage was set at 0.3 ml per 250 ml of milk, striking a balance between yield (26.30%) and the absence of bitterness. The experimental cheese exhibited faster, controlled acidification, reaching a pH of 4.31 by day 15, compared to 4.73 for the control. The highest yield was achieved with the experimental cheese (up to 24.68%). In sensory evaluation, the experimental cheese scored 18.2 versus 15.91 for the control, demonstrating superior texture and flavour stability during storage. The use of indigenous starter cultures and Solanum dubium extract helps stabilise the production of Djibna baida. Rapid acidification (pH < 4.5) provides a crucial safety barrier, while starter-mediated balanced proteolysis enhances organoleptic qualities. Conclusion: This optimised process serves as a key tool for ensuring food safety and extending the shelf life of this traditional cheese.