Ensuring Microbiological Safety in Chhana Production and Storage

Chhana is one of India’s most beloved traditional dairy products – a soft, acid-coagulated fresh cheese that forms the base for sweets like rasogolla, sandesh, rasmalai, and cham-cham. But because chhana is high in moisture and rich in nutrients, it is also highly perishable. The microbiological quality of chhana directly determines how safe and fresh it is for consumption. Whether it’s made in a small halwai shop or a modern dairy plant, the microbial load in chhana depends heavily on the hygiene maintained during production, handling, and storage. Let’s break down exactly what affects the microbial quality of chhana, which organisms cause spoilage, and how producers and consumers can keep contamination in check.

What is chhana and why is it vulnerable to microbial contamination? 🔗

Chhana is prepared by coagulating hot milk (usually at around 80°C) with an acid such as citric acid, lactic acid, or sour whey. The coagulated mass is then drained through muslin cloth to remove the whey, yielding a soft, moist product. As per FSSAI regulations, chhana should contain not more than 70% moisture and a minimum of 50% milk fat on a dry matter basis.

That high moisture content – typically between 55% and 65% – is precisely what makes chhana a favourable environment for microbial growth. It has a near-neutral pH, plenty of lactose for microbes to feed on, and sufficient protein and fat to support rapid multiplication of bacteria, yeasts, and moulds. Unlike fermented dairy products such as dahi or yoghurt, chhana lacks protective cultures that could suppress spoilage organisms. This means that any contamination introduced during or after production can lead to quick deterioration.

Key sources of microbial contamination in chhana 🔗

Contamination in chhana doesn’t come from a single source – it enters the product at multiple stages. Understanding these points of entry is the first step to controlling microbial load.

Raw milk quality 🔗

The quality of the starting milk matters enormously. Milk with high initial bacterial counts – from poor udder hygiene, unsanitary milking equipment, or lack of cold chain – will carry a larger microbial load into the chhana-making process. While the heating step (near boiling) during chhana preparation destroys most vegetative bacteria, heat-resistant spores from organisms like Bacillus species can survive and later germinate under favourable conditions.

Processing environment and equipment 🔗

In the unorganised sector where most chhana is made, utensils, muslin cloths, and work surfaces are often inadequately cleaned. Airborne fungal spores – particularly from Penicillium, Aspergillus, and Cladosporium – are among the most prevalent contaminants in food production environments. These spores can settle on freshly made chhana during the draining and cooling stages, initiating mould growth within days.

Human handling 🔗

Post-production handling is a major risk factor. Workers touching chhana with bare hands, using unclean packaging materials, or leaving the product exposed at ambient temperature all introduce bacteria. Research on chhana-based sweets sold in Kolkata found that E. coli was isolated from about 28% of market samples, with a significant proportion carrying enteropathogenic strains. This level of contamination points directly to poor sanitation and hygiene during manufacturing and handling.

Storage and transport conditions 🔗

Chhana has an extremely short shelf life. Without refrigeration, microbial growth accelerates rapidly. Studies on chhana stored at different temperatures have shown that delays in the dairy supply chain provide favourable conditions for microbial growth and rapid spoilage. Sweet manufacturers often immerse chhana in whey to maintain softness, which can help slightly, but does not replace proper cold storage.

Common spoilage organisms in chhana 🔗

The microflora of chhana typically includes bacteria, yeasts, and moulds. Each group contributes to spoilage in different ways.

Moulds: the primary spoilage agents 🔗

Moulds are perhaps the most visually obvious and commonly reported spoilage organisms in chhana. The genera most frequently isolated from chhana include Penicillium, Aspergillus, Mucor, Rhizopus, and Fusarium. These moulds cause visible surface growth – often appearing as fuzzy green, black, or white patches – along with unpleasant off-flavours and odours.

Research has confirmed that Penicillium is the most frequently reported spoilage genus in dairy products overall, followed by Aspergillus. In the case of chhana specifically, these moulds thrive because of the product’s high moisture and nutrient availability. Mucor species are also significant – they are widespread in nature and possess strong saccharolytic and proteolytic capacity, meaning they can break down both sugars and proteins in chhana, accelerating spoilage.

Certain moulds can also produce mycotoxins – toxic secondary metabolites that pose health risks even in small amounts. While not every mould strain produces mycotoxins, the risk is real enough that visible mould growth on chhana should be taken seriously, and the affected product should be discarded rather than simply trimmed.

Bacteria 🔗

Bacterial contamination in chhana includes both spoilage organisms and potential pathogens. Coliforms and E. coli are commonly used as indicator organisms – their presence signals faecal contamination or poor hygienic conditions. Staphylococcus aureus can be introduced through human handling, while Salmonella and Listeria monocytogenes are pathogens of serious concern in any fresh dairy product.

The FSSAI mandates that Salmonella and Listeria monocytogenes must be absent in paneer and chhana at both the manufacturing and retail levels. These are classified as safety indicator organisms, and their detection renders the product potentially hazardous.

Yeasts 🔗

Yeasts contribute to spoilage by fermenting residual lactose, producing gas, off-flavours, and sometimes a slimy surface texture. While generally less dangerous than pathogenic bacteria, yeasts reduce the product’s sensory quality and shelf life. Elevated yeast counts typically indicate inadequate processing hygiene or improper storage temperatures.

Fresh chhana vs. market samples: a comparison of microbial quality 🔗

There is a well-documented difference in microbial quality between freshly prepared chhana made under controlled conditions and chhana purchased from the open market. Laboratory-prepared chhana, where milk quality is controlled, equipment is sanitised, and the product is packaged and refrigerated immediately, consistently shows significantly lower microbial counts – both in terms of total plate count and specific spoilage organisms.

Market samples, on the other hand, are frequently exposed to contamination at multiple points: during transport in open containers, display at ambient temperature in shops, and handling by multiple people without gloves. Studies on chhana-based sweets from Kolkata markets have found that a high proportion of E. coli in milk sweet samples is likely due to inadequate sanitation and improper processing. This gap in microbial quality between laboratory and market samples highlights how much of the contamination is preventable through better practices.

FSSAI microbiological standards for chhana 🔗

India’s FSSAI has specified microbiological criteria for paneer and chhana that serve as benchmarks for both food business operators and regulators. These standards include limits for the following parameters at the manufacturing level:

Total Plate Count (TPC): The acceptable level (m) is 150,000 CFU/g, with the upper limit (M) at 350,000 CFU/g. Counts exceeding M indicate unsatisfactory hygiene. Coliform count: The acceptable level is 10 CFU/g, and the upper limit is 100 CFU/g. Yeast and mould count: Acceptable at 50 CFU/g with an upper limit of 150 CFU/g. E. coli: Must be below 10 CFU/g. S. aureus: Acceptable at 10 CFU/g, with an upper limit of 100 CFU/g. Salmonella and Listeria monocytogenes: Must be absent.

Products that fail to meet these standards – particularly on safety indicators like Salmonella – are classified as potentially hazardous and can lead to prosecution of the food business operator. At the retail level, FSSAI currently mandates testing only for Salmonella and Listeria, though the process hygiene parameters should ideally be maintained throughout the supply chain.

How to reduce microbial spoilage in chhana 🔗

Controlling microbial contamination in chhana requires attention at every stage – from raw material to the consumer’s plate.

Start with quality milk 🔗

Using fresh, clean milk with low initial bacterial counts is the foundation. Milk should ideally be pasteurised before being used for chhana-making in commercial settings. This eliminates most vegetative pathogens and significantly reduces the starting microbial load.

Maintain hygienic production conditions 🔗

All equipment, utensils, muslin cloths, and work surfaces must be thoroughly cleaned and sanitised before use. Workers should wear gloves, hairnets, and clean clothing. Implementing Good Manufacturing Practices (GMP) and HACCP-based systems at the plant level is essential for any commercial chhana operation.

Use appropriate packaging 🔗

Packaging plays a critical role. Chhana should be packed in food-grade, sealed packaging materials that minimise exposure to air and environmental contaminants. Vacuum packaging or modified atmosphere packaging (MAP) can further extend shelf life by restricting the oxygen supply that moulds need to grow. Studies on similar dairy products like paneer have shown that modified atmosphere packaging is considered one of the best techniques for extending shelf life.

Refrigerate immediately and consistently 🔗

Temperature control is non-negotiable. Chhana must be refrigerated at or below 4-8°C immediately after production. Even brief exposure to ambient temperatures – common during transport and retail display in India – can cause explosive microbial growth. Maintaining an unbroken cold chain from production to consumption is the single most effective way to extend chhana’s shelf life.

Consider whey immersion for short-term storage 🔗

A traditional practice among sweet manufacturers is immersing chhana in whey to keep it soft and prevent surface drying. Research indicates that this practice, combined with refrigeration, can help extend shelf life while preventing visible discoloration that sometimes occurs under cold storage alone. However, the whey itself must be fresh and uncontaminated for this method to be effective.

The role of biopreservation: an emerging approach 🔗

An area of growing interest is the use of lactic acid bacteria (LAB) as natural biopreservatives against mould spoilage. Certain LAB strains produce antifungal compounds – including organic acids, cyclic dipeptides, and fatty acids – that can inhibit the growth of common dairy spoilage moulds. A review published in Frontiers in Microbiology highlights that LAB biopreservation offers a promising “clean label” alternative to chemical preservatives, aligning with the growing consumer demand for natural, minimally processed foods. While this approach is still largely at the research stage for products like chhana, it represents a potential future tool for extending shelf life without compromising consumer expectations.

Why this matters for public health 🔗

Chhana and chhana-based sweets are consumed widely across India, especially in eastern states like West Bengal, Bihar, and Odisha. Many of these products are made in the unorganised sector where quality control is inconsistent. Contaminated chhana can cause foodborne illnesses ranging from mild gastroenteritis to more severe infections, particularly in children, the elderly, and immunocompromised individuals. Ensuring microbiological safety is not just a matter of product quality – it’s a public health priority.

Regulatory enforcement by FSSAI, consumer awareness about checking storage conditions before purchasing fresh dairy products, and the gradual adoption of HACCP-based quality systems in even small-scale sweet shops can collectively raise the microbiological standard of chhana across the country.

What do you think? Should FSSAI enforce stricter microbiological testing at the retail level for fresh products like chhana, or would better training and hygiene certification for small-scale manufacturers be a more practical first step?

References

1. https://fssai.gov.in/upload/uploadfiles/files/Chapter%202_1%20(Dairy%20products%20and%20analogues).pdf
2. https://pmc.ncbi.nlm.nih.gov/articles/PMC11394069/
3. https://pmc.ncbi.nlm.nih.gov/articles/PMC3209849/
4. https://www.sciencedirect.com/science/article/abs/pii/S095671352300097X
5. https://pmc.ncbi.nlm.nih.gov/articles/PMC5620633/
6. https://pmc.ncbi.nlm.nih.gov/articles/PMC8826399/
7. https://fssai.gov.in/upload/uploadfiles/files/Appendix%20B.pdf
8. https://link.springer.com/article/10.1007/s12088-011-0102-9
9. https://fssai.gov.in/upload/uploadfiles/files/Draft_Regulation_on_Microbiological_standards_milk_and_milk_products_31_08_2015.pdf
10. https://ndri.res.in/dairy-microbiology
11. https://www.researchgate.net/publication/368760313_Predictive_microbial_growth_modelling_for_an_effective_shelf-life_extension_strategy_of_Chhana_Indian_cottage_cheese