Considered a heart-healthy replacement for butter, Margarine is a fat spread prepared from various vegetable oils and hydrogenated fats, and is mainly used for flavour and baking purposes. As the quality of the vegetable oils and fats used in margarine preparation varies, the shelf-life of the margarine will also be affected.
Polyunsaturated fats during processing are highly prone to oxidation, and rancidity, especially when subjected to high degrees of temperature. Manufacturers use purified, bleached and deodorised vegetable oils as ingredients to prevent rancidity along with the use of antioxidants. Antioxidants preserve food by retarding deterioration, rancidity, or discolouration caused by oxidation. Mane Kancor, with its proprietary technology, has developed its own range of unique application-specific natural antioxidant solutions under the brand name OxiKan, refined rosemary extracts.
In the case of Margarine, shelf-life can be defined by its consistent colour, flavour and odour. Hence, we can assess the shelf-life of Margarine by testing its colour stability and fat oxidative stability.
In order to evaluate the efficacy of different natural and synthetic antioxidants in the colour and fat oxidative stability of margarine, a three-stage application test was carried out.
Accelerated Shelf-Life Analysis
The accelerated shelf-life study was conducted in the Velp Scientifica OxiTest Reactor. The reactor speeds up the oxidation process by the two accelerating factors: temperature and pressure. The instrument measures the absolute pressure change of oxygen inside the two titanium heating chambers at a constant temperature, thereby monitoring the oxygen uptake by reactive components in the sample to generate an Induction Time Value for further analysis. Induction Time is the initial change in chemical reaction post which reactions accelerate.
The samples (10 g) were placed in the titanium chambers under enclosed conditions of 90°C and 6 bar pressure. The longer the Induction Period, the more resistant a sample is to lipid oxidation.
The study has confirmed that among all antioxidants evaluated, OxiKan (Natural Antioxidant) and TBHQ (Synthetic Antioxidant) exhibited the highest antioxidant efficacy in prolonging the shelf-life of margarine.
The visual analysis of samples after exposure to accelerated oxidation was done by comparing them with different antioxidants against the samples that has no antioxidant additions. The analysis was done in terms of its colour and texture.
Colour evaluation of samples was done using Xrite colorimeter (Make – Xrite; Model: Colour i-7, SI No :47018230115; Colour iOC Professional with SLITaper, version 9.3.30). The sample was held in a Petridish (with Vents 35,0/10MM,10STUCK /BTL; Make: Grenier Bio-one; Serial No :627102). Measurement was conducted in reflectance mode.
The analysis clarified that the margarine samples with OxiKan (Natural Antioxidant) and TBHQ (synthetic antioxidant) have the brightest colour.
At the end of our evaluation, it was observed that highly-refined rosemary extracts such as OxiKan are very effective in preventing the rancidity of colour sensitive fat emulsions such as margarine, without causing any darkening of its colour. Rosemary Extracts, such as OxiKan can replace synthetic antioxidants such as TBHQ and Ascorbic acid in margarine stability and is a better alternative to natural Tocopherols in improving oxidative shelf-life