Long used as processing aids, enzymes may portend a future of making tasty foods healthier. And solving the trans fat issue is just the beginning. John Diehl investigates
The evolving emphasis on functional and nutritional foods as both a marketing priority and a research development area has given us cause to look closely at how nature makes and delivers key components of our diet in the foods we eat, and also how we digest and adsorb those components. Nature accomplishes a great deal of its key chemical reactions utilising enzymes. Enzymatic reactions as processing steps are efficiently catalysed, require less energy to react, mimic nature, and effectively resolve chirality so that we do not have to live with racemic mixtures. Historically, enzymes have been seen as catalysts to accomplish digestion/hydrolysis of complex or large moieties into simpler molecules, but gaining momentum is using enzymes in a reaction sequence to synthesise or transform molecules to create nutritional or organoleptic value. The precursors for ingredients that make a food more desirable or give it enhanced nutritional value often exist in the foods we eat every day; however, these attributes are not developed because of cost or lack of knowledge about how to exploit them.
Minke Noordermeer and colleagues at Utrecht University, the Netherlands, published a study in 2002 using soybean lipoxygenase and hydroperoxide lyase to produce C6 aldehydes from vegetable oils. These C6 aldehydes are an important piece of the flavour and aroma of almost all fruits and vegetables, but they are frequently ?lost? during processing because of their volatility. Using soybean lipoxygenase treatment on 6-hydroperoxy fatty acids to form an intermediate, followed by hydroperoxide lyase to produce a C6-aldehyde, offers the potential to re-introduce a key volatile component of a food?s organoleptic profile. In addition, it also subtly reduces triglyceride content and thus the tendency of them to shorten shelf life because of oxidation.
Flavour and fragrance manufacturers can utilise these reactions to synthesise natural versions of key C6 aldehydes needed for their created products. Likewise, foodservice product producers could maintain an organoleptic profile that suggests ?freshness? or ?freshly cut,? making consumption of salads, vegetables and possibly other produce more attractive for the consumer. Here the enzyme is being used in a traditional way as a processing aid/process catalyst.
Trans Fat Interesterification
The need to label trans fatty acid composition is one of the technical issues that will drive both the food and nutrition products industry during the next three to five years. Consumers have grown accustomed to an array of desirable food products that require partially hydrogenated vegetable oils both for functional and organoleptic purposes. Replacing these products will be difficult and in many instances ?structured? triglycerides will have to be produced and utilised. Enzymes can help in this process. Lipases can be used to accomplish interesterification of triglycerides where the triglycerides? fatty acids can be hydrolysed and then, in the presence of excess ?desired? fatty acid, the free fatty acids re-esterified to create new functional triglycerides.
Longer term, these triglycerides will probably be made using genetic engineering of common oil seeds such as canola and soy using the patents of Calgene (Monsanto) and DuPont Protein Technologies. Here the desirable triglyceride synthesis genes can be moved into a host temperate zone oil seed, the hybrid plant then bred using traditional techniques and grown in identity-preserved fields to minimise cross-pollination. The non-lipid fractions of the hybrid oil seed would be identical to a traditional oil seed and could be utilised by simply turning it back into that market stream—going to animal feeds, protein concentrate/isolate manufacturers and the like.
The interesterification can proceed quite effectively as excess free fatty acids exist to esterify to the mono- and di-glycerides that are created. Positional issues are also at play. Most lipases have a far greater affinity for the 1,3-positions than for the 2-position of the triglyceride; hence, if one?s objective is to change the middle fatty acid, there may be limited success. Some lipases, especially from Candida, can affect all three positions—but this is hardly a directed synthesis.
In order to accomplish a more directed synthesis, one might start with lecithin and use a phospholipase A2 enzyme to specifically hydrolyse and then re-esterify the 2-position. The phosphate group could then be removed and the 1,3-positions changed using a fungal lipase that will affect the two outside positions. Doing this type of reaction sequence, however, will not be without some price-point movement for users. Over time the manufacturers of these specialty triglycerides will manage to create economies, but initially the cost of the enzymes, the extra processing steps and the sacrifice in yields will be painful. However, the trend right now is toward healthier diets and an educated consumer will buy into this. Again, these enzymes are being used in a traditional way as a processing aid/process catalyst. Notable companies that have commercialised phospholipase enzymes include Novozymes, Sankyo and R?hm.
The Future Of Enzymes
But what about the use of enzymes in a ?what-if? scenario—how might enzymes be used to enhance both the eating quality of foods as well as the nutrition of the foods? Fact: Consumers have shown that when a healthier version of a food category is put in front of them, they will buy it once. However, if the product does not deliver the satisfaction they have come to expect at the table, they do not make a repeat purchase. What if we could leave the organoleptic profile of the food unchanged (rendering it desirable to consumers) and then have beneficial changes occur, in vivo, following consumption? Now we are talking about use of the enzyme as an active ingredient and not solely as a processing aid/process catalyst.
One case where this is possible already exists—an enzyme called levansucrase (fructosyltransferase), developed by Amano Enzyme. When used in combination with other existing digestive and carbohydrate isomerising enzymes, levansucrase will convert sucrose to desirable oligosaccharides in the gastrointestinal tract. Sucrose can thus still be used to sweeten a food and make it more palatable, but before the sucrose reaches the point of adsorption in the small intestine it has been hydrolysed to the monomer sugars, while the levansucrase converts the monomer sugars into beneficial 5-8 sugar oligosaccharides (in this case fructo-oligosaccharides).
But now we are talking about an active ingredient, not a processing aid. While the usage/ingestion levels would still be quite small, it is intended to perform its catalysis in the body, not in a neutral processing environment; hence, a food additive, not a processing aid. In addition, the levansucrase enzyme is produced by a microorganism that has not previously been utilised in our food supply, meaning that any company wishing to sell it would have to bear the expense of the GRAS approval process before commercialisation.
We?ll also see enzymes start to appear in foods as food additives to bring value nutritionally, not merely as a digestive aid. Another example is Triarco?s Aminogen, an enzyme added to whey protein powder to catalyse the breakdown of protein into amino acids, thereby increasing absorption and digestibility of the amino acids. Improving the utilisation of nutrients increases the value of foods, making them better for consumers and without affecting the taste profile of foods.
John Diehl is president of John Diehl Consulting Services, based in Illinois. He has also held positions in business development and sales for Valley Research, Amano Enzyme, DSM and Calgene. [email protected]
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