Magnetic Resonance Shows Promise As Means To Improve Food Quality

Two new studies suggest that NMR can improve the quality and shelf life of processed foods by probing the molecular-level behavior of ingredients and can identify the chemical mobility of tastes consumers prefer, such as which of two common forms of potassium delivers a salty, less bitter taste.

The findings were presented Sept. 7-9 at the Fourth International Conference on Applications of Magnetic Resonance to Food Science, which brought in researchers in a field that has taken off in the United Kingdom, where the meeting was held, and is rapidly growing in the United States.

"We have seen a rise in the questioning of the stability -- the safety -- of our food supply," said Shelly Schmidt, a professor of food chemistry at the U. of I. "A large number of food-safety issues have surfaced in the last few years. To the average consumer it may seem that our food supply is becoming less safe. We need to be sure that we are providing the highest quality and safest food in the world. Unfortunately, we don't understand enough about what makes a food safe."

For instance, she noted, a standard of measuring stability is to examine water activity to predict if and when food may spoil. But the technique has only a 50-50 chance of being accurate. In her talk, Schmidt described how three independent methods -- deuterium NMR, carbon 13 NMR and differential scanning calorimetry -- all used by the same researchers on the same samples of food could be used to accurately measure the mobility of water and solids and predict microbial growth.

"These new tools we have tested, particularly NMR, give us the power to probe and make the connection between the stability of a food and how we formulate it, how we store it and how we package it," she said. "We want to be able to say that a product is safe, and we want to be able to say it with greater accuracy than 50-50."

In the second study, researchers built on earlier work in Schmidt's lab that documented that sodium releases a saltier taste when it is not bound to the ions of other components of food, such as those in thickeners. Using NMR, the researchers analzyed potassium chloride and a potassium blend.

Sensory studies had found potassium chloride to be more salty but also more bitter tasting. Looking at the molecular makeup, NMR found that potassium chloride contained more tightly bound potassium ions. The more loosely bound blend provided a less salty taste but also reduced the unwanted bitterness. "So here, it's a compromise," Schmidt said. "You use the blend to obtain the taste perception that you want."

Knowing the molecular makeup that goes with taste, she said, offers the opportunity to "do things with the mix to meet desired taste attibutes" of food. Using NMR, a non-invasive technology, she said, is a way of tying structure and function to taste, texture and, most important, stability.