Metrohm's 743 Rancimat can be used to help determine the shelf life of processed food and ingredients.
Modern analytical methods are coming into use on an ever increasing scale in the fields of food production analysis and quality control and for the compliance with international and domestic standards.
Certain analytical procedures, while being accurate, do not always lend themselves to the ever increasing demands of increased production levels; they are just not quick enough.
One such technique within the food industry is the ability to predict the shelf life of a fat- or oil-containing product.
It would be disastrous for a company to introduce a fat or oil into their product that had only a few weeks before it became rancid by oxidation.
All oils and fats have a resistance to oxidation that depends on the degree of saturation, natural or added antioxidants, pro-oxidants or prior abuse.
Oxidation is slow until the resistance is overcome, at which point oxidation accelerates and becomes very rapid.
The length of time before this rapid acceleration of oxidation is the measure of resistance to oxidation and is commonly referred to as the 'induction period'.
The official method for determining the induction period, or Oils Stability (OS) as it is more commonly known, is by determining the Active Oxygen Content (AOCS official method Cd 12-57).
The Active Oxygen Method (AOM) involves the manual taking of samples over a period of time and performing a titration to determine the peroxide number.
This technique, while being accurate, is both labour intensive and takes many days to perform.
A new official method has been introduced for the determination of OS that is rapid and automated (AOCS official method Cd 12-92, AOCS Cd-12b-92), JOCS 2.4 28.2-93), SLB Section 7.5.4).
Metrohm's 743 Rancimat allows the simultaneous and rapid determination of Oil Stability Indexes (OSI) to be performed.
In the Rancimat, a stream of purified air is passed through a sample of oil or fat that is held in a heating block.
The effluent air from the sample is then bubbled through a vessel containing deionised water.
The conductivity of the water is continually monitored.
Once the oil starts to oxidise, volatile organic acids, predominantly formic acid, are swept by the effluent stream, through the deionised water, causing an increase in the conductivity of the water.
The OSI is defined as the point at which there is the maximum change in the rate of oxidation and is evaluated automatically in the Rancimat.
Features of the 743 Rancimat include: individual sample temperature settings for each batch of four samples; each sample can be started individually; one PC can control up to four measuring blocks, which means 32 samples can be processed at up to eight different temperatures; a temperature range from 50C to 220C; and a built-in air pump with automatic flow control.
The whole evaluation is automatically controlled by a PC, which runs software based on Windows 95/98/NT/ME/2000 or XP.
Automatic evaluation of the results according to set criteria are calculated by the software.
Metrohm said that the Rancimat can provide intelligent warehouse management of oils and fats and produce quick results at reduced costs.
Typical applications include: oxidation stability of oils and fats; oxidation stability of hazelnuts and almond oils; oxidation stability of waxes; oxidation stability of cereals, biscuits and cookies; oxidation stability of vegetable and motor oils; oxidation stability of bio diesel; and determining the effectiveness of antioxidants.
