Tuesday, February 25, 2014


Human beings, most of them, have a mindset regarding the freshness of foods they consume. This is especially true with many communities in India which consider preserved food as some thing not of desirable eating quality. Probably this is due to the fact that food is a material that can change its taste and other eating characteristics fast with progress of time at ambient conditions of temperature and humidity. Naturally those working in armed forces doing duty on far way and difficult terrains represent a microcosm of the Society and they also prefer to have "fresh" foods for their day to day dietary needs. Food technology as it exists to day had evolved over the last one century from simple traditional processes like sun drying and pickling and sugar steeping into a multitude of processes that can retain most of the sensory quality with minimum distortions. Still given a preference consumers will opt for fresh foods as obtained from nature directly without the intervention of process technologies!

Food technologists world over face stiff challenges in extending the life of foods but dramatic expansion of knowledge in food science and engineering have enabled them to meet these challenges successfully. But there is one area of technology where the challenge is much more formidable with very little success recorded. This is in developing a satisfactory technology that can keep the food in trim condition without affecting the typical eating characteristics of each one of them. Of course mechanically preservation of any food can be done assuring reasonable life of 12 months or less. Similarly technologies such as vacuum packing, ionizing radiation, freeze drying etc can even give shelf lives up to 2-3 years, However in all these cases the consumer will have to compromise on their expectations vis-a-vis optimum eating quality as some changes do take place either during processing or during storage. Pizza is such a product which is so non-homogeneous in nature that it is next to impossible to keep it for more than 3-4 days without affecting its aromas, texture and taste. Imagine the trials and tribulations of a group of scientists in developing an awesome technology for increasing the life of this much liked and typically American staple to more than three years. Extracts of a report from a US laboratory is recounted below for a better understanding and appreciation of this feat    

Pizza with a three-year shelf life will soon be joining the US Army's field rations menu. These infamous MREs (Meal, Ready to Eat) have a long and checkered history, acquiring such sobriquets over the years as "Meals Rejected by Everyone" and "Materials Resembling Edibles." Pizza has long topped the list of requested meals, but the task of providing a palatable slice of this complex food that will survive the required three-year shelf life has foiled all attempts. Now, the folks at Natick's Combat Feeding Directorate have achieved a minor miracle in food technology: stopping time for a slice of Pizza
MREs are the basis for feeding assault troops engaged in battlefield combat action. Each MRE provides 1300 calories of high-fat, high-sodium nutrition suited for active combat duty. Individual MREs come sealed in a four-layer plastic pouch measuring about 10 x 6 inches (25 x 15 cm) and weighing about a pound and a half (0.68 kg). The nominal shelf life of an MRE is three years at a storage temperature of 80 ºF (27 ºC), but they must also be able to survive short exposure to temperature extremes from -60 ºF (-51 ºC) to 120 ºF (49 ºC.) MRE packaging must be able to survive parachute deployment from an altitude of 1250 ft (380 m), and a free fall drop from 100 ft (30 m). Much more difficult than satisfying these physical and chemical requirements, however, is satisfying people's instinctive response to a food. The problem is well known in humanoid robotics, where it is called the uncanny valley. If the characteristics and behavior of a humanoid robot are very close to those of a natural human, people will accept the robot as an entity that might be a friend. If the approximation of human characteristics is poor, the robot will still be acceptable as a separate, non-humanoid entity. However, if the robot appears close to human norms, but not close enough, the robot will be rejected as strange and dangerous.

People also have an uncanny valley when it comes to food acceptance. It is often easier to come up with a new dish than to try to reproduce one that is enjoyed and valued. A new dish will be evaluated on its own merits, while a reproduction will be compared to an existing standard. For example, a slice of pizza which has a soggy crust and an oversweet taste will be evaluated differently than a sweet tomato bread pudding with cheese and meat topping. It all comes down to expectations, but our expectations can present extremely powerful barriers to surmount. So how do you make a slice of pizza that will survive three years unrefrigerated that still appears, smells, tastes, and has the mouth feel of a fresh slice of pizza? Natick senior food technnologist Michelle Richardson took on the task after non-soggy sandwiches entered the MRE choices in the 1990s.

"Pizza is a complex food consisting of four major components: bread, sauce, cheese, and sausage (pepperoni in this case). Each of these components has different characteristic levels of moisture, acid, and texture, which must combine harmoniously to produce a slice that will generally be viewed as a "good pizza." In contrast, another combination of bread, sauce, cheese, and sausage made from a hardtack biscuit covered with ketchup, Roquefort cheese, and finely chopped hot dogs won't remind anyone of a good pizza. Richardson had to reach deep into her bag of tricks to pull off the new pizza. The pizza dough had to be enhanced with humectants, substances like propylene glycol or sorbitol, that bind moisture within the bread. This both reduces the possibility of bacterial growth and the tendency of the sauce to make the crust soggy.

Another problem encountered with bread products is that they go stale with time. Contrary to popular opinion, staling is not caused by the bread drying out (which would be counteracted by humectants). Instead, the moisture in the bread migrates within the bread, causing the starch granules to recrystallize. In the end, Richardson and her assistants used gums and enzymes to hold the water within the starch granules, making the pizza crust shelf-stable. The challenge with pizza sauce is to keep the moisture held within the sauce, thereby preventing separation of the components and maintaining the sauce's freshness and mouthfeel. A mix of glycerin, rice syrup, and other sugars were used to make the shelf-stable pizza sauce. For enhanced shelf life, a low-moisture cheese is usually called for. However, one usually expects a pizza to have a reasonably soft, stringy cheese, properties usually not found in low-moisture cheeses. While Natick had used a low-moisture (probably Mozzarella) cheese in other dishes, this cheese became too browned in cooking, making the pizza look burned. This problem was addressed by altering the cooking schedule (time and temperature) and through making blends of various cheeses.

Pepperoni is both fermented and dried, resulting in an acidic, low-moisture sausage that is resistant to most bacterial growth. However, the low pH of pepperoni can encourage mold growth. The result of natural bacterial processes, this is a component which is difficult to control within narrow limits. Beyond the process of making pepperoni, the most important factors in rendering the sausage shelf-stable are osmotic drying and surrounding the pepperoni (and the entire pizza) in a nitrogen atmosphere.A native of Rhode Island, which has a sizable Italian population, Richardson says she set the bar high: "When I first started developing this, me and my daughter would go and taste pizza because I wanted to use that as my benchmark." The Natick pizza MRE is being prepared for final testing. In particular, several types of pepperonis and pizzas are being tested, both for spoilage and for soldier acceptance, to decide what version will make the final cut. We trust it will not disappoint".

Of course proof of the pudding is in the eating and whether the Armed Force personnel will heartily welcome this Pizza version remains to be seen. Looking at the results so far there does not appear to be any strong reason to suspect that this new innovation may be damp squib! What is notable in the above effort is the use of knowledge in microbiology, food chemistry, food engineering, packaging science, physical chemistry, sensory science and analytical chemistry in an integrated way to evolve the technology. India needs such high caliber scientific endeavor to technologize hundreds of ethnic foods for which many people including army personnel are craving for! Most of them have very limited shelf lives and use mostly manual processes to make making them unavailable in many parts of the country. Indian food scientists must wake up now and do some thing in this area.

For further reading refer to: http://www.gizmag.com/three-year-pizza-army-mre-field-ration/30941/?utm_source=Gizmag+Subscribers&utm_campaign=50a6aa78e1-UA-2235360-4&utm_medium=email&utm_term=0_65b67362bd-50a6aa78e1-90820233


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