Rancidity testing determines the level of oxidation in a sample. When lipids (fats and oils) go rancid, its nutritional value is compromised, and the lipids will take on a rancid taste and odor. Proper rancidity testing is an essential component in determining the shelf life of the product.
Eurofins staff will monitor rancidity, tracking primary and secondary indicator results as the study progresses. It is important to note the time it takes for these indicators to reach their threshold values in order to establish a product’s shelf-life. Eurofins offers the following rancidity testing:
Important Components to Rancidity Shelf-Life Testing:
- Peroxide Value (PV) testing determines the number of peroxides in the lipids. Peroxides are the initial indicators of lipid oxidation. Peroxides will continue to react and produce secondary products such as aldehydes.
- p-Anisidine (p-AV) testing indicates the number of aldehydes in the lipids. This test is often paired with PV, as aldehydes are the secondary indicators of oxidation. Aldehydes can produce strong objectionable flavors and odors at relatively low levels.
- TBA Rancidity (TBAR) also measures aldehydes (primarily malondialdehyde) created during the oxidation of lipids. This analysis is primarily useful for low-fat samples, as the whole sample can be analyzed rather than just the extracted lipids.
- Free Fatty Acids (FFA) testing determines the number of fatty acids that have been liberated from their triglyceride structure. Free fatty acids can produce strong flavors and odors at relatively low levels. Free fatty acids are hydrolytic rancidity (not oxidation) products and can be caused by microbial activity.
- Oxidative Stability Index (OSI) indicates how resistant a sample is to oxidation. The samples are subjected to heat while air (containing oxygen) is streamed through it. This process accelerates the oxidation process causing most oils to go rancid quickly. The samples are monitored and the time required for the sample to become rancid is determined. Samples that require longer times to become rancid, and more stable.