Seed flours derived from Chardonnay grapes and black raspberries could be used to develop natural preservatives to improve stability and consumer acceptance of fish oils, report researchers from the US.
Fish oil is notoriously difficult to incorporate into formulations since it is highly susceptible to oxidation. The result is a fishy taste and smell which can be off-putting for consumers.
However the nutritional properties of fish oil have been much in the spotlight in recent years, especially omega-3, of which fish is recognized as the best source. In order to help people consume omega-3 in their diet - and especially those who have an aversion to fish - formulators have sought to overcome the stability issues and deliver food products that are untainted by sensory issues.
Microencapsulation is a solution many ingredients firms have turned to, encasing the oil in a shell made of a more stable substance so that it does not come into direct contact with sources of heat, light and oxygen.
But a study conducted at the University of Maryland and published in the Journal of Food Chemistry suggests that ethanol extracts of Chardonnay grape and black raspberry seed flours could prove useful in suppressing oxidation, preserving the potency of the fatty acids, and also inhibiting microbial growth.
The researchers reported that both of the seed flour extracts were seen to suppress lipid oxidation and rancidity development in fish oil.
In particular, the black raspberry seed flour extract was seen to significantly reduce the degradation of omega-3 fatty acids under accelerated oxidative conditions.
They also found that the extracts could have a positive effect on food safety. Under experimental conditions, the black raspberry seed flour extract exhibited bacteriocidal activity against E. coli and inhibited the growth of Listeria monocytogenes at a level of 165 µg seed flour equivalents/mL.
The same effect was seen for Chardonnay seed flour extracts at 160 µg seed flour equivalents/mL.
When it came to quenching DPPH (diphenylpicryl-hydrazyl) radicals, both extracts performed, but the Chardonnay had the stronger ORAC (oxygen radical absorbance capacity) of 663 µmol Trolox equivalents per gram of seed flour and the higher total phenoloc content of 99 mg gallic acid equivalents/g flour.
"The data from this study suggest the potential for developing natural preservatives from these seed flours for improving food stability, quality, safety, and consumer acceptance," concluded the researchers.
Another aspect that boost the potential in the market place is the natural source of the seed flours. At present, 'natural' is a powerful force in the food industry, and there is increasing resistance at regulatory and consumer level - as well as from food retailers and manufacturers aiming to meet their demands - to synthetic preservatives.
Food manufacturers are getting increasingly adventurous with the food product categories they are adding omega-3 to. Last week Premier Foods' Branston brand in the UK announced the launch of baked beans with omega-3 - but the source of the omega-3 was not revealed.
Other categories in which omega-3 has turned up include bread, dairy products, baked goods, and chewy sweets.
Source: Journal of Food Chemistry (Elsevier)
Title: "Inhibitory effect of Chardonnay and black raspberry seed extracts on lipid oxidation in fish oil and their radical scavenging and antimicrobial properties"
Authors: Marla Luther, John Parry, Jeffrey Moore, Jianghong Meng, Yifan Zhang, Zhihong Cheng and Liangli (Lucy) Yu