Testing the shelf life of snacks and bakery foods

Snack foods contain oils that can develop a rancid flavour and odour through lipid oxidation and this limits their shelf life.

High temperatures, light and oxygen exposure can all accelerate the oxidative process in snack foods. By knowing the oxidation status of their bakery products and snack foods manufacturers can manage the quality and shelf life of the products.

The most important indexes that allow to estimate oxidative stability of finished products are: Free Fatty Acids (FFA) to determine the process of acidification of fatty component, Peroxide value to indicate the degree of primary oxidation and p-Anisidine value (AnV) to evaluate the formation of molecules (aldehydes and ketones) responsible for the organoleptic alterations. Furthermore, AnV analysis on oil is an indicator of excessive oil deterioration in the deep frying process.

Quality control from the oil to the packaged final product

Several methods can be used to predict the resistance of oil to oxidation, in order to be able to estimate the shelf life of snacks and bakery foods.

The accelerated aging method is based on speeding up the natural aging process by exposing the sample to high temperature and a continuous flow of air. Airflow delivers volatile oxidation products from the reaction cell into a vessel where they are adsorbed by the measuring solution (deionized water). The continuously recorded electrical conductivity of the measuring solution increases due to the absorption of the reaction products.

However, techniques founded on forced oxidation reactions, do not provide an actual knowledge of the original oxidative status of the sample, because they only cause an oxidative degradation.

Solvent extraction techniques using a Soxhlet extractor followed by gas-chromatography-mass spectrometry continue to be used as a reference method by the AOAC. However this method is slow and cumbersome, involves toxic solvents and requires trained personnel and a fume hood.

CDR FoodLab® is an analysis system designed to perform a quality control about the oxidative stability of finished snacks products. The analysis system does not require trained personnel and can even be performed at the production line.

Several analyses can be carried out at the same time on the same sample and, thanks to the multitasking mode, it is possible to process one analysis and to start another one at the same time, with the possibility to go back to the first one at any moment.

The system can be used to analyse 16 samples at the same time and constantly monitor the production process, obtaining exact and accurate answers in just a few minutes.

The CDR FoodLab method does not require the use of hazardous solvents or complicated extraction techniques. This means risks for the operator are eliminated and the environmental impact is minimised.

The method was developed in the CDR laboratories to let users ascertain the shelf life of bakery products, snacks and spreads by determining the acidity (FFA), peroxides (PV) and p-Anisidine levels. The method is simpler and results are obtained more rapidly than with traditional procedures.

Applications in the frying industry

CDR FoodLab system has been intensively used for quality control in the frying industry for many years. Free fatty acids, peroxides values and p-anisidine are among the most important analyses for this sector. The easy-to-use system can help manufacturers avoid off-flavours by ensuring the quality of the oil or even managing the entire frying process. With the possibility of shelf life determination CDR FoodLab becomes an important system that allows the frying industries to manage quality from the oil to the packaged final product.

How to use CDR FoodLab

CDR FoodLab determines the shelf life of finished snack products by monitoring the oxidation status and the rancidity of the oil contained in different products.

The system comprises an analyser based on photometric technology and a kit with disposable pre-vialed reagents with low toxicity, in packages of 10 tests.

Analyses can be performed in a few steps. Oil is extracted mechanically from the snack or fried product using a press, so no solvents are required. After the extraction step, the solid oil suspension is centrifuged (5 minutes) and the oil extracted is collected to perform the analysis (5 minutes).

A determined amount of the sample is then dispensed into a cuvette containing the buffer — generating a colorimetric reaction. Following photometric reading the result of the test is immediately available.

The CDR FoodLab analysis system has been specifically developed by CDR to respond to the needs of snacks producers of any size. It allows testing the shelf life of finished products (fried snacks and nuts) more rapidly and easily than traditional methods.