The global market for antioxidants for shelf-life extension is growing fast, with the total market more than doubling from $103.6M in 2011 to reach $246.1M in 2018, according to consultancy Frost & Sullivan (F&S). Crucially, the biggest chunk of that growth is expected to be in natural compounds, rather than synthetic, says the company's chemicals, materials and foods research analyst Ashwin Raj Ravinder.
"Synthetics are still higher as far as absolute volume goes because they're proven and tested and effective under the harshest conditions," he says. "But most of the growth is in natural compounds and it could be a real challenge for manufacturers to keep up with demand."
There are several reasons for this rapid growth. Globally, the ballooning middle class in developing markets is one factor.
"One of the biggest drivers today is the dramatic growth of the middle class in China and the BRIC countries. Of course, there is tremendous growth in the demand for products that have been traditional for those countries; but, beyond that, the demand is for a greater variety of products than ever," says Jorgen Sorenson, global business director for antioxidants and blends at DuPont Nutrition & Health. "This adds to the increasing complexity of the global food value chain. As that complexity increases and supply chains get longer, the challenge of keeping food products fresh all the way to the customer gets tougher. The farther it is from the farm to the fork, the more opportunity there is for fats to oxidise and become rancid."
At the same time, observers agree that the health and wellness megatrend is driving demand for more natural solutions. "The food market is now looking for cleaner-label declarations, which is common perhaps for all additives," says David Prime, business unit manager for protection products at Vitablend.
"Most companies producing or using foods with a fat and oil content likely to reduce shelf-life would prefer not to use additives at all, but it's very difficult in many cases to avoid. This is compounded by the increasing use of healthier, polyunsaturated fats in replacing more stable saturates."
So the pressure is on for antioxidants and natural solutions in particular.
The most common natural solutions are based on mixed tocopherols (aka vitamin E). These are a series of homologous compounds most commonly derived from soya. But supplies of tocopherols are being squeezed and that's driving up the price.
Manufacturers in Europe face an added challenge in trying to source tocopherols from soya, according to Prime: "Soya is the best source of the two most important homologues in natural mixed tocopherols, these being the delta and gamma homologues. These are the main components in our Tocoblend range. These two homologues are the most potent antioxidants for non-biological [food preservation] applications. As a result, and as the source is soya, the additional strain on this natural class of antioxidant is the ability to supply it as non-GM or identity preserved (IP)."
There are some alternative sources for tocopherols. For example, Vitablend produces a tocopherol product extracted from sunflower: Vitablend NAT L60. But this is only suitable for some applications because it contains relatively high levels of the alpha tocopherol homologue, which does not deliver such a potent preservative action in food as the delta and gamma varieties.
The main natural alternative to tocopherols is rosemary extract, which contains carnosic acid and carnosol. Prime says that taste has historically been a limiting factor in the use of rosemary extracts, but that is changing: "Today we see a vast improvement in taste profile, enabling their use in many applications previously considered too sensitive."
Both carnosic acid and carnosol are oil-soluble, making them particularly suitable for protecting oily or fatty products. In contrast, rosmarinic acid is water soluble and not classed as an additive, making it suitable for safeguarding the colour of water-based foods.
In fact, picking the right antioxidant or blend of antioxidants can be a complex business, balancing chemistry, cost and a number of other considerations. "For the most part, it comes down to chemistry," says Sorenson. "Chemistry is influenced by almost everything – the food formulation, the way food is packaged (it might be packaged in nitrogen instead of oxygen to delay oxidation), storage temperatures, the amount of light the product is exposed to, solubility of the antioxidants."
Prime says that choosing the right antioxidant is not an exact science, but he maintains that following some simple rules can help, such as checking what's already in the oil.
"Each antioxidant offers its own merit based on temperature tolerance, volatility, mode of action, synergy and cost. Vitablend looks at each case on its fundamental requirements but we pride ourselves on the full assessment of the technical capability of the antioxidant system by extensive in-house testing," he says.
Sorenson agrees that expert support from suppliers is a key ingredient for success. "You can use different modes of action to delay oxidation through metal chelation or through free radical scavenging; sometimes both are needed," he says. "Using electron spin resonance spectroscopy, we have developed highly sensitive methods for detecting both metal chelating and radical scavenging activity. We've been able to develop specific natural antioxidant blends that are much more effective than any single natural antioxidant solution can be."
"It's one of the reasons that the performance gap between natural and synthetic antioxidants is narrowing, and that helps us deliver better, more sustainable solutions. For instance, DuPont created a natural antioxidant/natural flavouring blend – Guardian Chelox L (EU) – that provides both metal chelation and radical scavenging, which makes it especially effective in high-lipid food emulsions such as mayonnaise and dressings."
Ravinder's market research for F&S also supports the idea that we're going to see a lot more blending of complementary antioxidants in future. "We're already seeing it with natural antioxidants. The cost of mixed tocopherols is rocketing so manufacturers are blending them with other natural antioxidants. We're also seeing growing interest in blending mixed tocopherols with ascorbyl palmitate to bring the price down in future."
Prime agrees that this will be the way forward for many companies: "Although ascorbyl palmitate is not a true natural compound it is recognised as being particularly safe for use in foods, being applied in most foods at quantum satis level and approved for use within infant nutrition applications. The beauty of ascorbyl palmitate lies in its synergistic capability with tocopherols in particular and it does offer capability also with rosemary, as seen in our Parolox series."
He adds that extensive work in the area of blending is helping manufacturers make the switch to natural and semi-natural antioxidant systems more cost-effectively than ever. However, Ravinder cautions that supply issues could still become problematic, especially in a largely GM-free Europe. "Our forecasts indicate that vertical integration through the supply chain may be needed to give suppliers access to the raw materials if there's a question of availability," he says.