Extending the shelf life of foods with a lactic acid solution

NEWS

Detecting forbidden meats in Halal food

Researchers at Chulalongkorn University’s Halal Science Center have developed an all-in-one strip test to quickly detect the DNA of five forbidden meats in a single test.

Food tainted with certain types of meat is forbidden by Islamic dietary law and is a major concern for Muslims, with surveys showing that pork can regularly be found mixed into beef in Thailand and other countries. These concerns motivated the Halal Science Center to invent a nucleic acid lateral flow assay (strip test) to detect foreign meat contamination, which consumers and food manufacturers can perform by themselves.

The strip test is a DNA technology, based on the principle of chromatography and hybridisation, using a membrane test strip made from nylon or nitrocellulose that allows a solution to flow through its porous surface freely. These membrane strips have a probe affixed to the surface at a specific location. When the multiplex PCRamplified target DNA solution from food samples flows through the immobilised probes, coagulation occurs and forms colour bands on the chromogenic membrane (strip).

Apart from cutting processing time and cost, the strip test detects traces of five prohibited meats in food (pork, dog, cat, rodent and monkey) in one single test. The test can be used with raw and cooked food, as well as other ingredients.

“This innovation certainly addresses the concerns that Muslim consumers and the general public have,” said Anat Denyingyote, Assistant Director and Head of Science and Technology Services Group, Halal Science Center. “The strip test detects targeted DNA, so it can yield a 100% accurate result within three hours, which is much faster than sending the samples to the lab that normally takes one to five business days. Moreover, it is also easy to use, cheap and convenient.”

While strip test users are currently limited to business operators, Halal inspection agencies and a few consumers with a science background, the plan is to make the strip test kit widely available at a cost that is claimed to be 10 times cheaper than a forensic lab test.

“We want Muslim consumers, the public and food business operators to be able to perform the test on their own at a reduced cost for safety and their peace of mind,” Anat said.

“Next, we will further develop the strip test into a comprehensive test kit capable of yielding faster results that can be used for onsite detection.”

Extending the shelf life of foods with a lactic acid solution

©stock.adobe.com/au/New Africa

The production of cheese results in large amounts of the side stream whey: about 10 L of milk is used to make 1 kg of cheese, leaving about 9 L of whey leftover. Now scientists have discovered a way to make valuable use of this by-product from cheese production by creating a solution that can extend the shelf life of certain food products.

Researchers at the National Food Institute, Technical University of Denmark have generated a lactic acid bacterium that secretes a food-grade preservative — antimicrobial peptide nisin — when grown on dairy waste.

Food-grade preservative nisin is approved for use in a number of foods, where it can prevent the growth of certain spoilage microorganisms as well as microorganisms that can make consumers unwell. For example, it can inhibit spore germination in canned soups and prevent late-blowing defects in cheeses — without affecting its flavour.

In theory, nisin could even be added to fresh milk to extend its shelf life. However, different countries have different rules stating what types of products nisin may be added to and in what amounts.

Many dairies are already turning a profit by extracting protein and lactose from the many tonnes of whey they generate, which they use, for example, in infant formula and sports nutrition. What is left behind from this can still be used to produce nisin.

In addition to ensuring better resource utilisation, there may be a financial gain from producing nisin as most commercially available nisin products contain 2.5% nisin and cost approximately $62/kg.

The work related to isolating the nisin-secreting lactic acid bacteria has been described in further detail in a scientific article in the Journal of Agricultural and Food Chemistry.