SDA-enriched soybean oil was associated with significant increases in the SDA levels in the meat of broiler chickens, and when chicken breast was cooked scientists from the University of Reading in the UK and biotech giant Monsanto report that the aroma, taste and aftertaste were unaffected.
“Approximately, 19 percent of the SDA consumed accumulated in the edible tissues (breast muscle, leg muscle and skin from the breast and leg),” write the researchers. “In the case of birds fed SDA soy, this amounted to 509 and 838 mg/100 g in the breast and leg meat (with skin), respectively. [Previous research] suggested that 3 g SDA was, in human subjects, equivalent to 1 g [eicosapentaenoic acid (EPA)].
“On this basis, the SDA accumulated in the breast and leg meat (with skin) of SDA-enriched soybean oil-fed birds would supply the equivalent of an additional 170 and 279 mg long-chain n-3 PUFA/100 g meat, respectively,” they added.
Monsanto and Solae are leading research into genetically modified soybeans containing SDA as a source of omega-3. Soybean oil is not normally a good source of omega-3 because it contains alpha-linolenic acid (ALA), which the body coverts inefficiently to SDA.
Fish oil arms race
In recent years the race has been on find a way to source DHA (docosahexaenoic acid) and EPA directly from plants for human use. Solae and Monsanto teamed up in 2007 to commercialise the latter's soybean variety developed specially to be rich in SDA. The rate of conversion of SDA to EPA is understood to be comparatively efficient - between 5.5:1 and 6:1.
The oil is being commercialized by Solae under the brand name Soymega. The ingredients attained GRAS status (generally recognised as safe) in 2009.
Not only are researchers looking into improving the omega-3 profile of certain plant crops, but research dollars (and pounds) are also going on increasing the omega-3 profile of meat. Reading University’s Ian Givens, co-researcher on this new study, is at the front line of research into such ‘functional meats’ and led part of the EU funded Lipgene project, investigating fats in the food chain.
In a recent interview with NutraIngredients, Professor Givens said experiences from the Lipgene project had suggested that if people were convinced a product would be beneficial, then it is much easier to gain acceptance, “and they are more likely to be convinced into using the products.”
“If you look back, the history of imposing long term dietary changes have never worked well across large populations,” stated Givens.
“The big attraction [of functional meats] is that the methods wouldn’t involve changing major dietary factors, just some of the components that make up existing diets,” he added.
One hundred and twenty broilers were divided into three groups. The birds were fed the same diet except for the oil used: One group received normal soybean oil, one group received the SDA-enriched oil, and the third group received fish oil. Birds were fed the diets from the age of 15 days until their slaughter (between 41 and 50 days).
Analysis of the fresh meat showed that the highest increases in the omega-3 content of the meat were observed in the fish oil-fed group, followed by the SDA-enriched soybean oil group, and then the control group.
The SDA and EPA content of breast meat was 522 and 53 mg/100 g meat, respectively, for the SDA enriched soybean oil group, compared with 37 and 140 mg/100 g meat, respectively, for the fish oil-fed group, and 13 and 13 mg/100 g meat, respectively, for the control diet group.
In terms of the sensory analysis, the researchers report that fishy aromas, tastes and aftertastes were linked to the omega-3 content of the meat, with this most noticeable in meat from the fish oil-fed birds.
“Although feeding the SDA-rich oil to birds had some negative effects on the sensory quality of the meat, these effects were much less marked than when fish oil was fed to the birds because of the lower long-chains n-3 PUFA content of the meat from birds fed the SDA-rich oil,” concluded the researchers.
Monsanto funded the study.
Source: British Journal of Nutrition
Published online ahead of print, doi: 10.1017/S0007114510004502
“The effect of feeding modified soyabean oil enriched with C18 : 4n-3 to broilers on the deposition of n-3 fatty acids in chicken meat”
Authors: C. Rymer, G. F. Hartnell, D. I. Givens