By Harsha Pore*
Consumers today are more inclined towards convenient and on-the-go food products with fresh quality attributes. Due to fast paced life, consumers do not have the time to spend long hours on cooking a nutritious meal. In response to the growing demand for convenient and fresh food, the food industry is now ready to explore advance technologies for manufacturing the consumer driven demand for high-quality fresh food products.
The traditional food processing technologies involves high heat treatments which can lead to significant loss in the nutritional and organoleptic parameters of food; thus, reducing the bioavailability.
Therefore, in lieu of such techniques, newer and advance food processing technologies are being sorted in order to serve the clean label tag to food industry.
This article focuses on recent advances in food preservation technologies for ready-to-eat and ready-to-cook food products. The traditional food technologies involve retort, canning, freezing, pasteurisation, and irradiation.
The recent and novel food processing technologies involves minimal processing with mild heat treatment for short duration of time to retain all essential nutrients and sensory properties. Here are some of the new food processing technologies:
MAP: Modified Atmosphere Technology
Modified Atmosphere Packaging is used to preserve fresh food products by controlling the atmosphere inside the package. MAP has become a norm as manufacturers have applied this technology to meet the market demand for fresh food with extended shelf life. It removes the atmospheric oxygen surrounding the product by inert gases such as carbon dioxide, nitrogen, argon etc, increasing the product shelf life by three times of its original shelf life. MAP helps to preserve foods by reducing microbial spoilage thereby increasing storability. MAP is done to maintain the freshness of the produce when purchased. Success of MAP packaged foods depends on the quality of raw material and hygiene practices followed during preparation and packaging as well as the gas mixture used for packaging in addition to the quality of packaging material. The gases used in MAP are CO2, O2 and N2. Researchers have successfully applied MAP to perishable foods like fruits, vegetables, flesh foods and certain dairy products.
HPP: High Pressure Processing
High Pressure Processing (HPP) is a cold pasteurisation technique by which products, already sealed in the final package, are introduced into a vessel and subjected to a high level of isostatic pressure (300–600MPa/43,500-87,000psi) transmitted by water.
Pressures above 400 MPa/58,000 psi at cold (+ 4ºC to 10ºC) or ambient temperature inactivate the vegetative flora (bacteria, virus, yeasts, moulds, and parasites) present in food, considerably extending the products shelf life and guaranteeing food safety.
High Pressure Processing respects the sensorial and nutritional properties of food, because of the absence of heat treatment, and maintains its original freshness throughout the shelf life.
High Pressure Processing is a natural, environmentally friendly process that respects the ingredient and helps maintain the fresh food characteristics like flavour and nutrients. It is a real alternative to traditional thermal and chemical treatments. High Pressure Processing has been successfully implemented in all type of food industries worldwide.
MATS: Microwave Assisted Thermal Sterilization
The Microwave Assisted Thermal Sterilization (MATS) technology was originally developed by Washington State University over a 10-year period, funded by the US government and a wide range of food companies.
MATS uses microwaves to speed up the heating process for packaged foods, essentially combining a continuous retort with a microwave. By reducing the cooking time, food quality can be significantly improved without compromising food safety or shelf life. By shortening the cooking time, food is exposed to high heat. The patented MATS and MAPS technologies preserve the colour, taste, and texture of food — eliminating the need for excess sodium, additives, and enhancers. Processing food with MATS is dramatically different than conventional food processing, also known as ‘retort.’
In conventional processing, packaged foods are placed in pressurised cookers at high temperatures for up to an hour. To mask the damage caused by the prolonged exposure to high heat, salt, flavour, texture and colour enhancers, and other unnatural ingredients must be added.
MATS simultaneously immerse packaged food in pressurized hot water and heats with microwave energy at a frequency of 915 MHz, eliminating pathogens and spoilage micro-organisms in a matter of minutes. This patented process preserves the nutrients, colour, texture and flavour of foods — while providing a shelf life equivalent to conventionally processed foods
MAPS: Microwave Assisted Pasteurisation System
Microwave Assisted Pasteurisation System (MAPS) is similar to microwave sterilisation (MATS) and in fact, can be performed on the same system. In microwave pasteurisation, foods and beverages are heated at 915 MHz to a temperature of 70-90° for up to 10 minutes, eliminating viral and bacterial pathogens. The result is a restaurant quality, ready-to-eat foods and beverages with a shelf life of up to 12 weeks. With a longer shelf life, MAPS-processed foods and beverages also help reduce food waste due to spoilage across the supply chain.
MAPS processing can also be used as a safety intervention step to improve the safety of prepared, ready-to-eat and frozen foods and batch ingredient sold or served by grocery chains, restaurant chains, convenience stores, nursing homes, hospitals, school meal programs, and commissaries/cafeterias.
PEF: Pulsed Electric field
Pulsed Electric Field (PEF) is a non-thermal food preservation technology that uses short electric pulses for microbial inactivation and gives high quality food product.
PEF technology involves the application of high voltage pulses to liquid or semi-solid food placed between two electrodes. Pulsed Electric Field (PEF) applications can be utilised to achieve disintegration of biological tissues or microbes. Application of pulsed electric fields of high intensity and duration – from microseconds to milliseconds – may cause temporary or permanent permeabilisation of cell membranes.
The basic principle of the PEF technology is the application of short pulses of high electric fields with duration of micro- to milliseconds and intensity in the order of 10- 80 kV/cm. Application of pulsed electric fields technology has been successfully demonstrated for the pasteurisation of foods such as juices, milk, yogurt, soups, and liquid eggs. PEF is a continuous processing method, which is not suitable for solid food products that are not pump able.
Osmotic Dehydration can simply be defined as controlled removal of water (diffusion) from food either by immersion of foodstuff in hypertonic (osmotic) solutions of sugar/salt or by direct addition of the osmotic agent.
Fruits and vegetables are highly perishable due to their high moisture content. To increase shelf life moisture content must be reduced in fruits and vegetables while retaining their nutritional, organoleptic and physical properties. Osmotic dehydration involves the following steps: washing of fruits and vegetables, peeling/cutting, sulphiting, osmotic treatment, and dehydration by drying method.
The most important products of commercial importance available in market made from fruits are murabbas of gooseberry (Aonla), apple, candies of different fruits and vegetables like pethas made by osmosis in sugar syrup. The process is economical, and does not involve use of any chemical additive; also, it can be used to decrease the post-harvest losses of fruits and vegetables.
Cold Plasma is a non-thermal plasma treatment given to the surface of food products or packaging materials to inactivate the microorganisms in terms of vegetative cells and spores. As the treatment is at low temperature the effects on the food quality and appearance is minimal.
Cold plasma is a novel non-thermal food processing technology that uses energetic, reactive gases to inactivate contaminating microbes on meats, poultry, fruits, and vegetables. This flexible sanitising method uses electricity and a carrier gas, such as air, oxygen, nitrogen, or helium; antimicrobial chemical agents are not required.
Overall application of cold plasma for microbial destruction on different food substrates like fruits, meat products, cheese etc. has been well discussed. Besides this, it is also used to alter the germination rate of seeds. It is an eco-friendly process which is used in the preservation of food.
Ultrasound is a form of energy generated by sound waves of frequencies that are too high to be detected by human ear i.e. 16 kHz. Ultrasound can propagate through solids, liquids, and gases. The application involves inactivation of micro-organisms. Ultrasound is an acoustic energy, but its effect is a physical energy. In food technology, ultrasound has a wide range of application. Microbial inactivation is the main efficient ultrasound application. The advantages of ultrasound are reduction in process duration and process cost.
Ultrasound treatment is a good opportunity to inactivate micro-organisms and enzymes when combined with heat and pressure. This triple combination serves a successful inactivation process in lower temperatures which provides a solution for industry to obtain fresh-like foods.
Ultrasound being non-toxic and eco-friendly is an emerging technology, known as Green Technology as it saves lot of energy and maximizes production.
Back in the era the objective of food preservation technologies used by the food industry is to control micro-organisms once they are contaminating foods. Today, food preservation technologies are based on the prevention of microbial growth or on the microbial inactivation. Focus on enhanced need of food quality and not compromising with the nutritional and sensory qualities of food has created an increasing interest in low temperature mild heat food processing treatments. However, further research is required to establish and expand the industrial applications of the above technologies and overcome high capital costs that may delay industrial adoption.