Spoilage in foods is essentially a process of oxidation and can be prevented by the exclusion of air from the container. This was concluded by Gay-Lussac in early 19th century after studying Nicholas Appert’s process of preserving foods (of both vegetable and animal origin) kept in glass containers along with water (fully covering containers), heated to 87ºC-100ºC in water bath and air-tight sealed with corks.
In the mid 19th century, Louis Pasteur added a new dimension of pasteurisation concept of food preservation to Gay-Lussac’s oxidation prevention theory. Pasteur proved that micro-organisms are the real cause of spoilage, majority of which are destroyed by heat treatment of foods at a high temperature.
However canning of foods in tin containers had started during 1810-20 by the efforts of Saddington, Durand and Underwood. In attempts to raise the temperature of water bath as high as 121ºC for pasteurisation or sterilisation of food, Issac Winslow in 1861 used calcium chloride as solute (technique of raising boiling point by adding solute to solvent or making solution) and A L Shriver invented pressure cooker or retort (technique of raising boiling point by increasing pressure).
Nevertheless, role of sugar and salt in preservation of food has been well known and applied. So sugar solutions (or syrups) and salt solutions (or brines) were used to preserve foods and beverages in containers in canning processes. Later on hermetic sealing facilitated tin packaging of foods.
In the 20th century, the processing time in food packaging processes was considerably reduced with the development of sterilisers or pasteurisers. In mid- 20th century in Australia, the spin pasteuriser was developed in attempts to preserve fruit pulp (or any pulpy, viscous food items) due to which high temperature short time (HTST) technique of packaging was facilitated. Further in attempts to save flavour of fruit slices rock-and-roll type of pasteurisation method was developed. Thin metal sheets and metal coated PVC, as packaging material, facilitated much more the food packaging process due to which aseptic retort packaging techniques to preserve high water activity foods, like prepared ready-to-eat vegetables, were developed.
The concept of active packaging, that means incorporating enzymes with container’s wall for shelf life extension or quality improvement, was introduced by Josef Hotchkiss, an American food scientist, in late 20th and early 21st century.
Also with technical developments in the field of nanotechnology, incorporation of food preserving metal (silver) and clay nanoparticles with container wall became possible. However side-effects of nanoparticles in human body have been observed, so nanotechnology in food preservation is not frequently advised by food authorities. The theory of pasteurisation (high temperature treatment) to preserve food articles was challenged by a group of American scientists in 21st century on account of killing both the good as well as the bad bacteria present in the foods whether milk or meats, fish or fruits, and vegetables. Therefore HPST (high pressure short time) techniques instead of HTST were developed and the process is called HPP (high pressure processing). However to install HPP plant is a costly affair, but worldwide contract manufacturing of HPP packaged foods and beverages is quite possible.
Contribution of Josef H Hotchkiss
Forum, a food tech cyber magazine, calls Prof. (Dr) Josef H Hotchkiss the Guru of Active Packaging. Prof. Hotchkiss is director of Centre for Packaging Innovation and Sustainability at Michigan State University. He has worked as director of graduate studies in the field of food science and technology at Cornell University.
According to an interview of Food Tech Source with him, Hotchkiss’ research efforts focus on introduction of biotechnology to food packaging in order to improve the quality, taste and/or safety of the product within. Among the most recent successes of Hotchkiss’ research team, the development of a juice container that removes the bitterness from grapefruit juice (while the product is en-route to the grocer’s shelf) is counted at top. He defines food packaging as a system of separating a food product from its environment to ensure freshness and quality. The message of Dr Hotchkiss is as follows:
“There have been a tremendous number of technological advancements in food packaging over the last 15 years. For the most part they’ve concerned the development of better or more suitable barriers — barrier means a system of separating a food product from its environment to ensure freshness and quality. These innovations have allowed us to have all kinds of new products, such as single-strength, high-quality refrigerated orange juice — which would not have been possible without some real breakthroughs in packaging. It looks like a milk carton, but it’s actually very hightech. Nonetheless, these packaging innovations have all been passive in that they were simply an improvement of the barrier concept. Active packaging, on the other hand, focusses on the development of materials which in some way interact with the product to improve its quality, safety, shelf life and usability.”
“It’s recently gained any popularity. So, it’s really quite a new area and not on the dinner table or in the grocery stores yet, except in some limited ways. But we believe it is the future of packaging. We’re always trying to push the envelope. Right now we are concentrating on what we call bio-active packaging, in which we are combining advances in biotechnology with advances in material science, to bring some potentially innovative ideas to the packaging realm.”
“Adding enzymes to the interior packaging is a great example of that. Enzymes are very useful in processing foods, and in many cases they can improve the product. Our initial demonstration of this was to put an enzyme in a film material used in packaging in order to reduce the bitterness in citrus juice.”
“How could we demonstrate that active packaging could improve the quality of a product during storage? We knew that citrus products generally have a problem with bitterness. So, we got the idea of introducing an enzyme that degrades the bitter compounds in grapefruit juice onto a film which was used to line the inside of the juice carton. To reduce bitterness, we introduced naringinase, which is an enzyme-derived fungus.”
“It turns out that the bitterness in grapefruits is due primarily to a common plant compound that has sugar molecules attached to it. Naringinase clips off those sugar molecules, effectively making the juice taste sweeter.”
“The main problem faced was getting sufficient activity at refrigeration temperatures, which juices are commonly held at. It was needed to increase activity per unit area of film in order to get sufficient interaction between the enzyme and the juice.”
“We focussed on immobilisation—tried a number of different supporting films that immobilised and held the enzyme, plus were economically viable and were approved for food contact. It was pretty much just trial and error. We were ultimately successful to the extent of demonstrating that you can incorporate an active enzyme into a film, and when that film contacts the product—even at refrigeration temperatures—it can improve the product vis-a-vis its taste, over what would be considered a normal shelf life for that product.”
“It’s a function of area, of loading of enzyme into the film. Of course, temperature plays a role, as does the nature and the pH of the product. So, one has got to look at each case. For example, if one wanted to remove lactose from milk, for people who are lactose intolerant, without adding the enzyme directly to the milk, one could incorporate lactase into the wall of the container and package the milk. If one had sufficient activity one could reduce the lactose concentration of the milk during shipment.”
“Otherwise for it to work, one has to add lactase directly to the milk. It’s always a problem adding something directly to foods because then people consume it. Or, instead, one could use an immobilised enzyme reactor, but those systems have not been particularly successful because they have problems with fouling and clogging up, and with bacterial growth, and relatively frequent regeneration times. So, active packaging might prove a beneficial alternative.”
“One could talk about controlled cholesterol reduction or adding other types of flavour-enhancing enzymes… one can think of lots of potentially good uses for enzymes in food. And with active packaging there’s no need to add the enzymes directly.”
“Furthermore there are enzymes that metabolise cholesterol, so, at least in theory it’s possible to reduce the cholesterol content of a food item. I do not know if anyone’s done it, but you could put a cholesterol-consuming enzyme in packaging material that, in theory anyway, would reduce the cholesterol of a product like milk.”
“The beauty of enzymes is that they are very, very specific in their activity. Typically they do not affect other components. Cost is a funny thing when talking about enzymes and other products of biotechnology. Proctor and Gamble has put an enzyme system into a laundry detergent which breaks down cellulose so that it makes your clothes appear brighter because it takes away the fuzz that develops on cotton-based fabrics. If you can put that much cellulase in detergent and still sell it at a reasonable cost, through biotechnology it seems to me you can do almost anything.”
Nanotech innovation in packaging: Hotchkiss’ views
Hotchkiss told Tom Philpott of motherjones.com in June 2014 that while nano-materials were quite attractive to the food industry as a way to cheaply prolong the shelf life of packaged foods, they currently were not widely used because no one knows for sure what kind of risks from ingesting exquisitely tiny amounts of nano-materials may or not represent. As a result, the food industry is waiting on the sidelines until more safety research emerges.
FSSA 2006 should critically analyse innovative packaging
In India too, active and nanotechnological packaging systems might be in use, therefore, with a viewpoint of public health the FSS Act should critically analyse and come up with laws regarding packaging materials and technology.