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Alternatives to synthetic antioxidants
 3 min read

Colours and flavours determine the freshness perception of meat products. However, oxidative processes in meat form off-flavours and toxic compounds, change colour, lower shelf-life and cause nutrient and drip losses during storage and distribution. Adding antioxidants may delay or decrease the rate of oxidative processes. Consumers have concerns about the safety of synthetic antioxidants. Hence, researchers compared natural antioxidants and synthetic antioxidants in several studies.

Most effective

Results are not conclusive; however, several natural sources have been identified as potential alternative to synthetic antioxidants. The effectiveness of natural antioxidants depends on circumstances, such as specific type of meat, type of fat, type of product, pH, processing, other ingredients, package conditions, exposure to oxygen, concentration and more. For example, minced meats are exposed more to air and bacteria than intact muscles due to the larger surface area and therefore develop more rancidity. Therefore, natural antioxidants need to be tested per product to know which antioxidants works for each product. Below, results of two experiments with beef patties are given as an example.

Experiment 1

Researchers from Lincoln University in New Zealand added antioxidants on meat during the grinding process of beef patties. They compared the natural antioxidants resveratrol, carnosine, quercetin and rutin. Their results indicated that the antioxidant activity of resveratrol is superior to quercetin, rutin and carnosine. The effect of resveratrol is dependent on concentration and method of application to meat. Carnosine was not effective at normal pH<6 but may have an application in food products in which the pH can be adjusted.

Use specific natural antioxidants for specific purposes

Alaa Bekhit Senior Lecturer at Otaga University in New Zealand

Experiment 2

Researchers from China Agricultural University also added antioxidants on meat during the grinding process of beef patties. They compared natural antioxidants vitamin E, carnosine, grape seed and tea catechins compared with the synthetic antioxidant BHA. Addition of all antioxidants inhibited fat oxidation and retarded the formation of metmyoglobin. Metmyoblobin gives the meat the characteristic brown colour occurs as it ages. Carnosine and grape seed extract preserved red colour best. However, fat oxidation was prevented most by the synthetic antioxidant BHA, followed by tea catechins and vitamin E.

Colour

The colour of meat is influenced by the form of myoglobin. Myoglobin is a pigment in muscles that contains iron, just like haemoglobin in blood. The purple colour of fresh red meat is a reflection of the dominance of native myoglobin. When oxygen binds to the myoglobin, the meat becomes bright red, which consumers associate with freshness. However, when the meat becomes older, the iron in the myoglobin loses an electron and the meat becomes brown. Free radicals are produced during fat oxidation. They can change myoglobin, which causes discolouration. Some antioxidants preserve the colour because they are free radical scavengers.

Fat oxidation

Fat oxidation occurs under influence of light, enzymes or by exposure to atmospheric oxygen, named auto-oxidation. Oxidized fats cause the development of rancid flavour. Antioxidants disrupt fat oxidation by scavenging free radical generated during oxidative processes or chelating transit elements that initiate oxidative processes.

Advice

“Use specific natural antioxidants for specific purposes”, advices Alaa Bekhit, expert in natural antioxidants from Otago University in New Zealand. "Antioxidants that inhibit fat oxidation maybe cannot stop colour change and those that stop colour change may not be the best ones to stop fat oxidation. Also some natural antioxidants that are obtained from herbs and spices may have strong flavours and this needs to be evaluated for each product.” If you have more questions for Alaa Bekhit, you can fill out the get in touch section below.

This article was adapted from

The effects of natural antioxidants on oxidative processes and metmyoglobin reducing activity in beef patties. 2003. A.E.D. Bekhit, G.H. Geesink, M.A. Iliana, J.D. Morton, R. Bickerstaffe. Food Chem. 81, 175-187.

Effects of natural antioxidants on colour stability, lipid oxidation and metmyoglobon reducing activity in raw beef patties. 2015. Fang Liu, Qian Xu, Ruitong Dai, Yuanying Ni. Acta Sci. Pol. Technol. Aliment. 14(1), 37–44

Want to get more information about this topic?
Get in touch
Contact person:
Alaa Bekhit
Function:
Senior Lecturer
Company:
Otago University
Country:
New Zealand


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