FFC NMR relaxometry can offer solutions for the food and agriculture industries, particularly for quality control, shelf-life and denomination of origin. The NMRD profile is sensitive to dehydration, oxidation, spoilage, and the addition of additives including adulterants that may lead to fraudulent products Below are some examples of these applications.
Please contact Stelar if you would like information on any application not listed here or you would like to try a new application.
Cocoa butter is an important ingredient of chocolate whose crystal form is important for the formation of the hard, shiny commercial chocolate we enjoy eating. Indeed, cocoa butter crystallizes in six different forms and only the beta-crystals are important for correct formation of commercial chocolate. Studies on the liquid, pre-crystallization state of cocoa butter have been lacking and here FFC NMR relaxometry has shown utility for diffusion and phase changes. The technique was used to study the molten and cooled states of cocoa butter and was shown to be particularly sensitive to phase changes below 1 MHz.
Milk sours when bacterial fermentation transforms the sugars to lactic acid. Acid may denature proteins present and drive protein aggregation both of which affect the NMRD profile. Fermentation may be monitored by FFC NMR relaxometry, as demonstrated by a Stelar in-house case study, which was able to monitor spoilage of a refrigerated milk-based drink product. In this case, low magnetic field measurements were a critical advantage, and the shape of the NMRD profile was diagnostic.
1H NMRD profiles of an unbranded milk-based refrigerated drink product before and after artificial spoilage (acidification). Data from a Stelar in-house study.
The dry-curing ham process involves salt diffusion & moisture migration in opposite directions. The analytical methods used to monitor this process are usually destructive and time-consuming. It has been demonstrated that FFC NMR relaxometry in combination with another NMR method (quantitative magnetization transfer) is a good approach towards a fast and non-destructive characterization of dry-curing hams of different protein content. The quadrupolar peak area obtained by FFC relaxometry can be quantified and thus serve as a marker for the dry-curing process.
Meat has a short shelf-life and thus needs to be stored rigorously at cold temperatures. A Stelar in-house study showed that FFC NMR relaxometry can show how quickly meat, such as pork loins, can dehydrate over a period of 20 hours and over 12 days. The “quadrupole” peaks shown in the NMRD profile of pork are due to the immobilized proteins in the meat. The FFC technique could indeed be used to elucidate the freshness of meat products by monitoring water loss.
Fast measurements of the water status of intact blueberries using FFC NMR relaxometry can be easily transferred to quality control applications including freshness and shelf-life monitoring.
1H NMRD profiles of blueberries. [ See ]
Honey fermentation is promoted by microbial activity, which is influenced by the variation in water mobility associated with the temperature. Honey is of large value to the food industry, thus choice of the storage temperature which can prevent honey deterioration is highly important. FFC NMR relaxometry was used to understand the amount and nature of the water present in honey, which is important to predict its conservation and stability. The technique found dramatic changes in honey component distributions, which suggested an elevated risk of spoilage. [ See ]
A method of recognizing liquified honey has also been proposed: heating the honey at 30 °C resulted in irreversible molecular structure changes as shown by FFC NMR relaxometry. [ See ]
FFC NMR relaxometry has been shown to be a very promising tool for quick evaluation of vegetable oil quality with advantages over other time-consuming extraction and purification procedures. FFC was used to obtain the diffusion coefficient of rape oil and was compared with that obtained by the well-recognized pulse gradient spin echo (PGSE) NMR method and showed a good agreement. The advantages of FFC NMR relaxometry over the PGSE NMR method, are that it is not limited by the strength of the gradients, is not time-consuming, and determination of the diffusion coefficient from the experimental data requires only a simple mathematical operation.
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