Encapsulation and fish

Encapsulation from fish is  for innovation. The highlights of this month’s science have been novel encapsulation and controlled release, and getting more from fish. Controlled release The controlled release of ingredients, from flavours to nutrients, has been receiving more research attention. However, according to Dérick Rousseau, PhD, from Ryerson University in Canada, few examples, if any, of food-related commercial applications of controlled release exist. Dr Rousseau told attendees at the IFT International Food Nanoscience Conference in New Orleans that while the science is coming along, the understanding of controlled release of ingredients for food is still full of holes. “When it comes to foods and the concept and application of controlled release, what we do know is dwarfed by what we don’t,” he said. There are options available to food scientists however, and Dr Rousseau has his finger in a lot of research pies, being active in the study of many different types of controlled release. These include microemulsions containing nano-scale particles, self-assembled dairy proteins, and phase-separated hydrogels. He said that micro emulsions offer the easiest application, and they are thermodynamically stable, meaning they are formed almost instantly on mixing, and they also do not separate over time. But it’s not all plain-sailing, and innovation is handicapped by the limited choice of food grade surfactants. On the topic of self-assembling proteins, Dr Rousseau told FoodNavigator this was “intriguing.” Indeed, fellow IFT speaker Kees de Kruif from NIZO Food Research in the Netherlands told this website that, while the majority of research in this area to date has focussed on dairy proteins, the field could be expanded to non-dairy proteins, in principle. “Self-assembling of proteins is common. In fact, it’s more of a rule than an exception. If we can manipulate this self-assembling of proteins at the nanoscale, I see a big future for it,” he said. Fishy alternatives Recent food safety fears such as BSE in cattle and avian ‘flu in poultry prompted consumers and marketers to look for products containing no animal derivatives, and this is affecting ingredients like gelatine. Despite certain companies and institutions claiming to have conclusively proven that there is no link between gelatine and BSE, this has not stopped the search for alternatives. Researchers from Malaysia reported earlier this month that fish gelatine (especially from warm water fish) “possesses similar characteristics to porcine gelatine and may thus be considered as an alternative to mammalian gelatine for use in food products.” Gelatine is a translucent colourless substance, created by prolonged boiling of animal skin, connective tissue or bones. It is most commonly used as a stabiliser, thickener, or texturiser in foods such as ice cream, jams and yoghurt, and is also used to improve the mouthfeel of various products. “Production and utilization of fish gelatine not only satisfies the needs of consumers, but also serves as a means to utilise some of the byproducts of the fishing industry,” they wrote in the journal Food Hydrocolloids. In a different study, researchers from Mexico reported that protein hydrolysates from Pacific whiting, an abundant and under-utilised fish, could substitute functional compounds such as bovine serum albumin and sodium caseinate. “Results in the present study showed that hydrolysates produced from Pacific whiting (Merluccius productus) muscle can be used as food ingredients or additives to impart a desire characteristic to food products or increase food storage stability, acting as emulsifying, foaming or dispersing agents, in sausages, mayonnaise, salad dressings, beverages, creams, etc., all these in a broad pH range,” they in the journal Food Chemistry.

Self-assembling proteins offer golden food future

There is a big future for exploiting protein’s natural tendency to self-assembly into micelles or nanotubes, says a leading researcher in the field.

“Self-assembling of proteins is common. In fact, it’s more of a rule than an exception. If we can manipulate this self-assembling of proteins at the nanoscale, I see a big future for it,” said Professor Kees de Kruif from NIZO Food Research.

The majority of research in this area to date has focussed on dairy proteins, with the potential of casein micelles and alpha-lactalbumin nanotubes being explored, Prof de Kruif told FoodNavigator following his presentation to attendees at the Nanoscience conference at IFT Annual Meeting and Food Expo in New Orleans.

The protein casein makes up about 80 per cent of the protein content of cow’s milk (30-35 about 2.5 gram per litre grams per litre) and is found naturally in the form of spherical micelles with diameters ranging from 50 to 300 nanometres. The stability of these micelles during processing also makes them a very attractive nano-encapsulator.

Indeed, according to Prof de Kruif, Mother Nature designed the casein micelles to concentrate, stabilise and deliver nutrients to the newborn.

In nature, calcium phosphate is bound inside the micelles, but food scientist can replace calcium with other minerals or vitamins, thereby providing a delivery system for certain bioactive molecules.

“Caseins are very beautiful proteins, with functionalities in food unsurpassed by other food proteins,” said Prof. de Kruif. Indeed, they are very stable to heat, and the stability can be increased by cross-linking with transglutanimase (TGase).

Nanotubes

Another dairy protein receiving interest from researchers is bovine alpha-lactalbumin.

By adding an enzyme to the protein, Prof de Kruif and his team were able to produce food-grade nanotubes.

“This was the first time that anyone made man-made nanotubes from proteins,” he said.

In addition, for food scientists, the tubular structures are more interesting than the spherical ones, he said.

Moreover, by taking the science further, and manipulating this self-assembly process, new proteins with new functionalities can be produced, said Prof de Kruif. “They could replace the use of gelatine.”

These nanotubes could also be used for encapsulation of ingredients, he said. Moreover, the nanotubes would not need to sealed and could be left open-ended. And how far away are we from using such nanotubes in food?

“This is still a bit far fetched in the sense that you can make the nanotubes and you can stabilise them, but they are too expensive for the food business at present,” he said.

“We need investment to scale this up.”

Beyond dairy

Since the self-assembling of proteins into intriguing structures is common to all proteins, Prof de Kruif says that, in principle, non-dairy proteins could be used.

“In theory, you need a long stiff molecule, like gelatine,” he said. “We should look at elongated structures because they’re the interesting ones, not the globular proteins.”

Study with plant proteins is still in its infancy, but the study performed with milk proteins should be translated to other proteins.

Prof de Kruif looks at the issue from a material science rather than food science point of view and focuses on understanding what properties the protein should have. “It’s the same as a chemical engineer asking what properties a plastic should have before they start developing it.”

Nanoboom

The application of nanotechnology and nanoparticles in food are emerging rapidly, and some analysts predict that nanotechnology will be incorporated into 16.4bn worth of food products by 2010.

However, enthusiasm over the rate of progress and the possibilities is being tempered by concerns over possible downsides of the scienc