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FOOD PROCESSING

Food beyond light years

Saturday, 18 March, 2023, 12 : 00 PM [IST]

Harish S, Harini U, Harisankar A & Sinija V. R

Space food is a kind of food which is consumed during space missions in the weightless space environment. Dietary nutrition is crucial to the safety of astronauts' lives, not just because it is possible to maintain sufficient nutrition by consuming the proper nutrients, but also because in the long-term social psychology of space flight, the right meal is crucial. foods should have the qualities of compactness, lightness, portability, and consumption, as well as get past the negative impacts of vibration and radiation, as well as unfavorable environmental elements, like minimal pressure. Space food is different from normal food in terms of composition, storage, and nutritional value.

Natural Food: Foods packed in flexible pouches and in ready to eat form (like granola bar, nuts).

Refrigerated Food: Food which requires refrigeration that is lower temperature to preserve the food like cheese.

Intermediate Moisture Food: Food in which partial amount of water is only removed, leaving some water to maintain a soft texture. These kinds of food can be consumed without any further processing (pears, dried peaches, and beef jerky and apricots).

Rehydratable food: Water is removed from the food to facilitate storage. Water is replaced in food before consumption. Rehydratable food includes beverages and other food items such as hot cereal, oatmeal.

Irradiated Food: Irradiated foods are now commonly used in space mission, especially beef steak and smoked turkey are majorly used, where these foods are cooked, packed in flexible pouches and sterilised by ionising radiation to preserve the food even stored in ambient condition.

Frozen Food: Foods which are frozen quickly to prevent the formation of large ice crystals to present the structural damage and preserve freshness of foods like casseroles and chicken pot pie, quiches.

Fresh Food: Food which are consumed in original form that is it is neither preserved artificially nor processed, example banana and apple.

Thermo stabilized Food: Thermo-stabilised foods which are heat processed food, which can be stored in the ambient temperature which did not degrades. Most of fish especially tuna fish and fruits are thermo stabilised in can, these can be open easily and consumed.
Food Consumed during Space mission.
Table 1: Some human flight for Space Mission and the food specifications

Space mission	Specification of food units	Food consumed
Mercury	Space flight lasted for few minutes to a full day, where the physiology of chewing, swallowing, drinking and chewing of different food where tested	Freeze dried foods, semi-liquids in aluminium toothpaste-type tubes
Gemini	In this mission, variety of food were consumed with improved packaging material such as cellophane were used	Bite size cube foods, dehydrated juices etc
Apollo	This mission uses same packaging material in Gemini mission but with further improved food variety	Coffee, bacon, tuna, salad, beef pot roast and spaghetti
Skylab	Food warmer trays were introduced in this mission.	Food consisted of ham, mashed potatoes, ice cream, steaks and asparagus
Apollo-Soyuz Test project	Spacecraft consist of small heating unit and food are packed in metal can and aluminium tubes	Meat, meat paste, fruits and nuts, cake, coffee and soup

Evaluation of Space Food
Space food come in to act from the Mercury space mission in the early 1960s. During that time space food came in three different form such as tube foods, example apple sauce which are consumed directly into mouth by pressing the tube like toothpaste, second is cube foods which are small cubes of compressed foods can be swallowed in one month, third is freeze dried powdered which can be consumed after rehydration. In the Apollo missions (1968-1972), food was improved in terms of packaging.

Hot water facility was equipped in Apollo mission which used to rehydrate the food. In 1973, Skylab food system was considered tastier food compared to other space missions, includes 72 kind of food to choose from, with 6 days menu cycle. Skylab contain refrigerator and food heaters, crews were enjoyed food varieties such as chilled drinks, desserts, lobsters, ice cream, filet steaks.

Processing technique used for space food.
Freeze-drying technology
Freeze drying, is a technology often referred to as lyophilisation, where the food is frozen followed by sublimation and desorption to remove remain water from food. Whirlpool developed the first freeze dried product that is ice cream under the NASA contract. But it crumbles in space while eating. Additionally, NASA has collaborated on the development of a novel method for creating genuinely ‘instant’ ready-to-eat rice.

3 D printing technology
The term ‘3D printing of food' describes the use of 3 D printers to create food by printing it in 3D structure by layer-by-layer stocking of the food ingredients. By using 3D printing, relatively easy space cooking activities can be completed, astronauts' health information can be used to produce the right food and prompt adjustments can be made to fit their nutritional and taste preferences. The ink cartridges contain carbohydrates, some powdered nutrients and dried milk powder for printing space food.

Irradiation sterilisation
Shelf life of the food can be extended without heating the food by using the irradiation technology. Its remarkable benefits include ease of use, high productivity, environmental friendliness, safety, low nutrient loss, maximum food original flavour preservation, and a decrease in chemical additives.

Today, irradiation technology are used for preserving space food, hospital diet and ready to eat foods One of the methods NASA frequently uses to sanitise food for space travel is radiation technology.

High pressure processing
A technique called high pressure processing uses high pressure to treat items and produce a germicidal effect. 200 MPa and 600 MPa are the minimum and maximum pressures for high pressure processing, respectively. NASA conducted a study to determine the PATS food's shelf life (pressure-assisted thermal sterilisation), and the findings revealed that after three years of storage, the pressure-assisted thermal sterilisation (PATS) fruits colour and texture were superior to those in retort bags.

Microwave assisted thermal (MAT) sterilisation.
This innovative technology enables for in-container processing and offers superior nutrient retention than more traditional methods. The use of water as a heat-transfer medium in the microwave can eliminate many of the drawbacks of conventional sterilising techniques, including uneven heating and edge effects.

NASA examined the retort procedure and microwave assisted thermal sterilisation to see if using less heat during processing could help preserve food micronutrients and increase shelf life. Comparing the nutrients stability there was no difference between MAT product and retort product.

Other processing technique
The term "hurdle technology" describes the scientific synthesis of a number of elements that work together to decrease the toxicity of degradation of food and enhance the shelf life of food by preserving the quality.

To fit the nutritional requirements of space crew, NASA begun the research work on microencapsulation of healthy meal, probiotics.

Packaging of current space food
Edible film
Edible film composed of lipids, protein, polysaccharides, starch and composite materials are frequently used. Applications for edible films include packaging flavouring powder in fast food and also used for packaging vegetables, fresh fruits, frozen goods and meat.

It preserves the food and enhance flavour retainment during transportation and storage by inhibiting water vapour and gas migration. Major advantage is that it won’t generate waste as it is biodegradable.

Metal Can
Tinplate, aluminium alloy, and other types of metal can packaging have good barrier qualities that can improve the shelf life of food by up to three years. During Skylab mission most of food stuffs are packed in aluminium cans to preserve the food up to two years.

This type of packaging material is used for manned space mission, example Russia supplied food stuffs for international space station. This packaging is thick yet has an excellent barrier. This package form is inappropriate for use in long-manned flying missions due to the weight of the packaging and the challenges involved in disposing of waste.

Retort pouch
Retort pouches composed of multiple layers of different material such as plastic film and metallic foils were used to reduce volume and mass. It replaces the heavy rigid rectangular rehydratable packaging material, and a trash compactor section, which are used to cut down the waste generated.

According to NASA research, the retort pouches greatly slowed down the physiochemical changes of butter cookies and rancidity compared to the packaging material which did not have non-metalised film.

High barrier packaging
During the Gemini mission, packaging material with strong water vapour and oxygen barrier properties was created (1965–1966). The most popular high barrier material, ethylene-vinyl alcohol (EVOH) copolymer, not only performs well as a barrier but also offers advantages in terms of physical strength.

This material can be used to package foods that are acidic, medium-moisture, and dehydrated.

Other packaging with application prospects
Due to their capacity to make food packaging with qualities such as lightweight, high strength, strong barrier, and multi-function, Nano materials offer a wide range of potential applications in the aerospace industry. The need for space food packaging materials can be satisfied by the nanomaterials found in composite packaging. Nanomaterials are, thermally stable, have high flame retardance, strong barrier properties and can improve the shelf-life of food by three to five years.

Basic Criteria for Space Food

Safety
Food system should be free from microorganism, physical or chemical risk to astronauts.

Nutrition
The food should provide sufficient nutrition to the astronauts, as most of the space mission are failed due to the nutrition deficiency of astronauts.

Usability
Food system should be user friendly, mean that it is easy to cook food with a shot span of time, unless time spent in normal home kitchen.

Resource minimisation
All inputs and outputs relating to food preparation, packaging, and disposal of waste, which have to be minimised.

Reliability
If the food system is lost, result will be catastrophic. so, the system is validated properly in the manner which suits for realistic space environment.

Variety
Boring Food menu can cause menu fatigue, even the food gives adequate nutrients, so the variety of food in menu should be ensured in terms of providing food like processed foods, grown foods.

Palatability
Food should be enjoyable for the astronauts in the terms of preparation and consumption because even the food satisfies other basic criteria such as nutrients requirements, if the food is not palatable, astronauts will not consume adequate amount of food needed to support their health condition.

Stability
Most important is that stability of food through the entire space mission is very important, it should be palatable and satisfy the nutritional requirements throughout the entire space mission.

Table 2: The challenges involved in the development of space food for long-mission human space flight.

1.High Nutrient Food

2.Extended food shelf-life products

3.Safe cooking in partial gravity

4.Vitamin delivery

5.Optimized packaging material for space

The focus was shifted from limiting crew mass to filling the nutrients requirements of astronauts.

NASA assign 18 -24 months for most food provision though which is not enough for long space flight mission

Microbial contamination of food causes severe health problems to the crew member. Food preservation treatment used on the earth may not be efficient in space

A nutritional study is needed to identify the nutritional requirement of the astronauts, which is very important to prevent the astronauts from nutrition deficiency

The packaging material used should be in the manner of, high barrier materials, lower mass to support long mission space flight and that is compactable for processing, disposal and should not produce huge waste.

It is probable that the health and performance of space crew members might be jeopardized without a sufficient food system. Hence a balance between resource utilization (such as crew members’ mass, crew time, and energy source) and the nutrition requirement of a crew member, acceptability of the food system and safety measures must be maintained when designing adequate food systems for future missions. In essence, the food should be in acceptable condition throughout the space mission, food should be safe even after processing and cooking, and the food are packed and formulated in a way that should not affect the mission viability in terms of mass, but the food should provide sufficient nutrients to a crew member for maintaining the crew health and performance.

(Harish S belongs to National Institute of Food Technology, Entrepreneurship and Management, Thanjavur (NIFTEM-T), Tamil Nadu; Harini U belongs to National Institute of Food Technology, Entrepreneurship and Management, Thanjavur (NIFTEM-T), Tamil Nadu; Harisankar A belongs to National Institute of Food Technology, Entrepreneurship and Management, Thanjavur (NIFTEM-T), Tamil Nadu; Sinija V. R belongs to National Institute of Food Technology, Entrepreneurship and Management, Thanjavur (NIFTEM-T), Tamil Nadu. They can be reached at sinija@iifpt.edu.in)