Microbiological quality of zabady (yogurt) produced by small-scale industries and households in Khartoum and Gezira state, Sudan

Abstract

Background: Zabady (yogurt) is widely produced in Sudan by households and small-scale dairies, often without standardized hygiene or temperature control. Such informal production systems increase the risk of microbial contamination and compromise product safety.

Objectives: This study aimed to assess the microbiological quality and safety of traditionally produced Zabady and the raw milk used in its preparation across different seasons and locations in Khartoum and Gezira States, Sudan.

Methods: An analytical study was conducted during the summer and winter of 2018–2019. Samples of Zabady and raw cow’s milk were collected from four localities. Microbiological analyses included total viable counts, lactic acid bacteria, coliforms, E. coli, Staphylococcus aureus, yeasts, moulds, and Salmonella spp. Yeasts and lactic acid bacteria were identified using classical biochemical and morphological methods. Sensory evaluation was performed using a semi-trained panel.

Results: Microbial contamination varied significantly by season and location. Summer samples showed markedly higher microbial loads, including elevated counts of coliforms, S. aureus, and spoilage yeasts. Salmonella spp. was detected only in samples from Eastern Nile. Many samples exceeded international microbiological limits. Sensory quality declined significantly during storage and correlated with higher microbial loads.

Conclusions: Traditionally produced Zabady in Sudan presents substantial microbiological hazards, particularly during summer, due to inadequate hygiene and lack of temperature control. Improved manufacturing practices, mandatory pasteurization, and strengthened cold-chain systems are essential to ensure product safety.

Novelty: This study provides the first integrated seasonal and regional assessment of the microbiological quality of traditionally produced Zabady in Sudan. It uniquely combines pathogen detection, spoilage yeast profiling, and sensory evaluation, identifying contamination hotspots and demonstrating clear links between microbial load and sensory deterioration. The findings offer practical, evidence-based guidance for improving safety in informal dairy production systems.

Keywords: Zabady; yogurt; Sudan; microbiological quality; lactic acid bacteria; spoilage yeasts; food safety.