Food & Beverage News: F&B Specials - Emerging Process Technologies

India is expected to become the fastest growing national market worldwide, with demand benefiting from above-average gains in food and beverage production. The challenge to catch up with the growing population of one billion people/consumers and the participation in globalisation will lead to major investments in the food processing industry. Up gradation of technology, therefore, becomes essential. While pursuing the hi-tech route for modernising our industry, adequate examination is necessary to make them sustainable under the Indian conditions and environment. Hi-tech ventures, no doubt, are more suited to the export-oriented industry which can absorb high investments and super costs of production. Reflecting on current trends, this article focuses on some of the most recent applications in high-pressure technologies, food microbiology, and modern thermal and non-thermal operations to prevent the occurrence of food-borne pathogens, extend shelf-life of foods, and improve the safety, quality, and nutritional value of various food products. India, with the second arable land in the world, and with diverse agro-climatic zones across the country, has tremendous production advantages in agriculture, with the potential to cultivate a vast range of agricultural products. For example, India produces 41% of world’s mangoes, 30% of cauliflowers, 28% of tea, 23% of bananas, 24% of cashew nuts, 36% of green peas and 10% of onions. This strong base in agriculture provides a large and varied raw material base for food processing. These advantages if leveraged optimally, can translate into India becoming a leading food supplier to the world.

Process Technology
Though there is tremendous potential in the food processing industry, it needs strong and dependable chain facilities to support the increasing production of various perishable products like milk, fruits, vegetables, poultry etc. Any attempts to project emerging trends during the new millennium must be viewed in the backdrop of anticipated changes in the global trade of food commodities under the WTO regime. Further, a number of major influences which will govern the future trends in new products development so far as global food is concerned. Some of the technologies use in the Indian food processing sector have been mentioned below

Aseptic Processing and Packaging:
Considered as the single most important innovation for food products in the last half-century, it involves producing shelf-stable products by sterilizing the product and the packaging material or container separately and filling in a sterile environment. It was popularised in India with the success of fruit juices, drinks & milk such as Frooti and Amul Taaza.

Milk with a long shelf-life is currently produced by three different processs:

Conventional sterilization
After a preheating stage to 800C in bulk, milk is bottled in conventional filler. After sealing, bottles are sterilized on a datum of 110/1150C for 30 minutes. This process gives often a strong cooked flavour and brown color to the end-product, and is now limited to the production of small batches of flavoured milk. Failure rates remain generally within acceptable levels but sometimes increase with high ambient storage temperatures – 25/300C.

UHT treatment
Milk in bulk is heat-treated at high temperature – 140/1450C – during a short holding time – 2 to 10 sec –before being aseptically filled in aseptic packaging (plastic bottles, cardboard/ plastic/ al complex,). Heat resistant proteases can affect the stability of milk during the UHT treatment itself or during its storage. A selection of raw milk in which only limited bacterial growth has occurred can be useful to produce stable UHT milk. UHT treatment limits the brown color of the milk, denaturation of proteins and development of cooked flavour.

Controlled & Modified Atmosphere:
In this system, the oxygen, carbon-dioxide and nitrogen gas levels are controlled or modified in a well-controlled distribution system. The shelf-life of such treated items can be extended from a small number of days to many days or even few weeks. This system has now come of age in our country, and is mostly prevalent for fresh or semi-processed foods. For eg, the shelf-life of apples can be considered in different conditions.

As can be seen apples can be stored up to 40 weeks in CA storage. The products like Apple, Pear, Banana, Kiwi, Strawberry, Blue Berry, Red Current, Avocado, Plum, Cherry, White Cabbage, Chinese Leaf, Asparagus etc. are suitable to be stored in CA Storage.

Thus apple can be stored up to 40 weeks in CA storage. Other fruits and vegetables that are suitable to be stored in CA storage include apple, pear banana, kiwi, strawberry, blue berry, red current, avocado, plum, cherry, white cabbage, Chinese leaf, asparagus, etc.

The benefits of controlled atmosphere storage include longer storage life, improved product quality at point of sale and less chemical input.

Controlled Atmosphere Storage ensures:
● Longer Storage Life
● Improved product quality at point of sale
● Less Chemical Input

High Pressure Technology
Using high pressure can quickly pasteurise, or in some case sterilise, food products with little or no heat treatment. This results in products that have a good natural taste and texture, while retaining those nutritional factors that would otherwise be degraded by heat e.g. vitamins. Generally, fruit based products and milk products are treated by high pressure.

Fruit based products Fruit juices
High pressure is used to replace one of at least two heat treatments (pasteurization) steps used normally in fruit juice production. This treatment inhibits or destroys enzymes and microorganisms. The juices after high pressure treatment are usually stored in bulks at 40C.

Pressure treated juice has a vitamin C content close to fresh juice compared to heat treated juice which is less than 80% of the starting material.

Jams
The jams are produced using selected pectins which solidify upon pressure treatment at ambient temperatures. The fruit, sugar and pectins are introduced into the flexible packaging which is sealed and then pressure treated. These jams are characterized by their colours and taste which are identical to the fresh fruit.

Milk based products.
The aim here is to replace either pasteurization or micro filtration with high pressure. It has been found that milk pasteurized by high pressure can be kept at refrigeration temperatures for several weeks. Pressurization at 7,000 atmospheres for 10 minutes at 200C can reduce to normal flora of milk on acceptable levels.

Membrane Processing:
Recently, membrane processing has gained importance over conventional processes in food industry for its advantages that are well known and established. Membrane processing has presented new possibilities for the production of newer intermediate dairy products that can be used in different foods based on their functional properties.

Membrane technology techniques include (a) reverse osmasis for concentration, to complement or replace evaporation, (b) nano- filteration for desalting and deacidification, concentration and purification, (c) microfiltration for clarification instead of centrufuges and sterilization instead of heat, (d) ultra filtration for fractionation, concentration and purification, (e) electrodialysis for demineralization instead of ion-exchange and (f) pervaporation instead of extraction and / or distillation. These applications, which are already commercial, are being used in dairy industry, fruit juice industry, sugar refining, corn refining and soyabean processing.

Whey Processing
Whey comprises 80-90% of the total value of milk entering the process and contains about 50% of the nutrients in the original milk: soluble protein, lactose, vitamins and minerals. Whey as a by-product from the manufacture of hard, semi-hard or soft cheese and rennet casein is known as sweet whey and has a pH of 5.9 – 6.6. Manufacture of mineral-acid precipitated casein yields acid whey with pH of 4.3 – 4.6.

Different whey processes :
Whey must be processed as soon as possible after collection, as its temperature and composition promote the growth of bacteria. Otherwise the whey should be quickly cooled down to about 50C to temporarily stop bacterial growth.

Casein recovery & fat separation
Casein fines are always preset in whey. They have an adverse effect on fat separation and should therefore be removed first. Various types of separation devices can be utilized, such as cyclones, centrifugal separators or rotating filters, Fat is recovered centrifugal separators. The fines are often pressed in the same way as cheese. After which they can be used in processed cheese and, after a period of ripening, also in cooking. The whey cream, often with a fat content of 25 – 30%, can be re-used in cheese making to standardise the cheese milk; this enables a corresponding quality of fresh cream to be utilised for special cream products.

Cooling and pasteurisation
Whey which is to be stored before processing must either be chilled or pasteurized as soon as the fat has been removed. For short time storage, 10 – 15 hours, cooling is usually sufficient to reduce bacterial activity. Longer periods of storage require pasteurization of the whey.

Concentration of total solids Concentration
Whey concentration traditionally takes place under vacuum in a falling-film evaporator with two or more stages. Evaporators with up to seven stages have been used since the mid-seventies to compensate for increasing energy costs. Mechanical and thermal vapour compression have been introduced in most evaporators to reduce evaporation costs still further.

Drying
Basically whey is dried in the same way as milk, i.e. in spray dryers. Spray drying of whey is at present the most widely used method of drying. Before being dried, the whey concentrate is usually treated as mentioned above to form small lactose crystals, as this results in a non-hygroscopic product which does not go lumpy when it absorbs moisture.

Fractionation of total solids from whey Protein recovery
Whey proteins were originally isolated through the use of various precipitation techniques, but nowadays membrane separation (fractionation) and chromatographic processes are used in addition to both precipitation and complexion techniques. The process that has been most extensively used for separation of whey proteins from whey serum is heat denaturation. The precipitated protein formed by this process is either insoluble or sparingly soluble depending on the conditions prevailing at denaturation; it is called heat-precipitated whey protein (HPWP).

Protein recovery by Ultra Filtration
Native protein concentrates have a very good amino acid profile with high proportions of available lysine and cysteine. Whey protein concentrates (WPC) are powders made by drying the retentates from ultrafiltration of whey. They are described in terms of their protein content, % protein in dry matter, ranging from 35% to 85%. To make a 35% protein product the liquid whey is concentrated about 6-fold to an approximate total dry solids content of 9%.

To obtain an 85% protein concentrate the liquid whey is first concentrated 20-30 fold by direct ultrafiltration to a solids content of approximatively 25%; this is regarded as the maximum for economic operation. It is then necessary to diafilter the concentrate to remove of the lactose and ash and raise the concentration of protein relative to the total dry matter. Diafiltration is a procedure in which water is added to the feed as filtration proceeds in order to wash out low molecular components which will pass through the membranes, basically lactose and minerals.

Defatting of whey protein concentrate (WPC)
Defatted WPC powder containing 80 – 85% protein dry matter is a very interesting option for some applications, e.g. as a replacement for white of egg in whipped products such as meringues

And as a valuable ingredient in various food and fruit beverages. Treatment of the whey retentate from a UF plant in a microfiltration (MF) plant can reduce the fat content of 80 – 85 % WPC powder from 7.2% to less than 0.4%. Microfiltration also concentrates fat globule membranes and most of the bacteria in the MF permeate is routed to a second UF plant for further concentration; this stage also includes diafiltration.

Chromatographic isolation of lactoperoxidase & lactoferrin
Generally speaking, use of natural bioactive agents is of very great interest in products like infant formulas, health foods, skin creams and toothpaste. Examples of such components are the bioactive proteins lactoperoxidase (LP) and lactoferrin (LF) existing at low contents in whey, typically 20 mg/l of LP and 35 mg/l of LF. The Swedish Dairies Association (SMR) has developed a patented process based on chromatography for isolation of these proteins from cheese whey on an industrial scale.

Supercritical fluid extraction
It is still, by far, the most widely adopted technique for separating and purifying products in a wide variety of industries, including the food industry. Nevertheless, the reduction of undesirable residues of organic chemicals in the final product remains the prime concern of the industry.

This technology is used for reduction of residues of organic chemicals in the final food product. A pure Supercritical fluid can be defined as any compound at a temperature and pressure above the critical values or critical point. For example, for carbon dioxide one of the most widely used Supercritical fluid. The critical temperature and critical pressure are 310C and 74 atm respectively. Above the critical temperature of a compound the pure, gaseous component cannot be liquefied regardless of the pressure applied. Around the critical point the visual distinction between liquid and gas phases and the difference disappears. In the supercritical environment only one can phase exist.

For any substance as the critical point is approached, many of its important properties undergo drastic changes like thermal conductivity, surface tension, heat capacity and viscosity. Supercritical fluid extraction (SCFE) is based precisely on this feature of rapid property change with only slight variations of pressure in the vicinity of the critical point. These drastic changes make Supercritical fluid a preferred choice over liquid solvents with the same density. The basic principle of Supercritical fluid extraction is that the solubility of a given compound (solute) in a solvent varies with both temperature and pressure.

Advantages of Supercritical fluid extraction:
The advantages of SCFs as compared to that of conventional liquid solvents for extraction make it specially suitable for producing a variety of natural extracts for the food industry. SCFs have solvating powers very similar to that of liquid organic solvents, but with higher diffusivities, lower viscosity, and lower surface tension.

Spinning Cone Column Technology (SCC) for Flavour Management
The Australian company Flavourtech has applied its unique Spinning Cone Column Technology (SCC) to the capture of flavours from food and slurry products. Flavoaurtech’s Spinning Cone Column is the world’s fastest, most efficient and cost-effective method for the capture and preservation of volatile flavour components, from all kinds of liquid or slurry substances. During the production of the base extracts and concentrates, over 70% of the desirable aroma is destroyed. The Spinning Cone Column is the centre of state-of-art Integrated Extraction System (IES) that enables the production of full-flavoured, concentrated extracts. This system integrates flavour management techniques virtually unknown outside the flavour industry with non-traditional soluble solids extraction.

The patented design of the SCC results in a unit, which, unlike more traditional systems, allows flavour recovery to take place faster, at lower temperatures and without damage to either the stripped product or the collected flavour.

PEF processing:
Pulsed electric field (PEF) processing uses strong pulsed electric currents to deactivate microbial cells, effectively preserving foods with little or no actual heat. For food quality attributes, PEF technology may be superior to traditional heat treatment of foods because it avoids or greatly reduces the detrimental changes to the sensory and physical properties of foods.

Aqua Ammonia Absorption Refrigeration Plants
In an aqua-ammonia absorption cycle, the absorbent aqua ammonia liquid absorbs the ammonia vapours from the chiller.

(The author is a senior consultant for dairy & food industry)

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