New Delhi, Aug. 11: India's cooperative dairy sector has cautioned consumers against buying milk or processed milk products from retail outlets that do not maintain them under continuous refrigeration and has announced fresh steps to assure the quality of their products.

The National Dairy Development Board and Mother Dairy, two of the nation's largest milk suppliers, have also said consumers should avoid purchasing milk from unregistered suppliers since some of them may compromise the maintenance of the refrigerated cold chain.

The advisory issued by senior cooperative dairy sector officials comes amid long-standing concerns that some unscrupulous dairy operators adulterate raw milk supplies while some retail shops shut off refrigerators during the night to save on their electricity bill costs.

"We're making additional investments to enhance quality assurance, maintain cold chain and put our franchises under greater scrutiny," T. Nanda Kumar, the NDDB chairperson, said today after a meeting with state dairy federations, milk suppliers and food safety regulators.

The cooperative dairy sector procured over 12.5 million tonnes of milk across the country during 2013-14. Most of this is sold as pasteurised milk, while some gets processed into butter, cheese or ice-cream, among other products.

Food safety regulators have during routine inspections in some states in recent years detected adulterants such as urea and other chemical compounds in milk. "We ourselves have four quality checkpoints - covering village collection points, transport and processing," Kumar said.

A nationwide snapshot survey on milk adulteration by the Food Safety Standards Authority of India four years ago had detected large proportions of samples from various states that did not conform to standards prescribed by the FSSAI.

Some milk samples even had detergents as an adulterant. All the samples from Bihar, Chhattisgarh, Jharkhand, Odisha, Bengal and Mizoram did not meet standards either because of the presence of water, glucose or other adulterants in the samples, the FSSAI had said in its report on the 2011 survey.

The NDDB, Kumar said, will strengthen the sampling and testing system through automatic milk testing machines and try and enforce the implementation of the standard operating procedures to maintain refrigerated cold chain by franchises.

But dairy sector officials say consumers also need to be aware that some retail outlets that sell pasteurised milk or processed milk products may not store the products under the required cold temperatures - typically below 4°C.

"They probably do this to save some money on electricity bills," said S. Nagarajan, the managing director of Mother Dairy, a subsidiary of the NDDB that was launched in 1974. It sells milk and processed products in several cities.

"For four decades, we've covered the electricity bills of all Mother Dairy milk-vending booths so that there's no incentive for them to shut off refrigerators during the night," Nagarajan said.

Over the years, dairy cooperatives have established a cold chain system that allows milk to be chilled quickly after it is collected in villages. About 8,500 bulk milk-cooling systems have been installed in villages across the country. Kumar said about 75 per cent of market milk sourced from the cooperative dairy sector is delivered through insulated vehicles.