How does the freeze drying process work in preserving food ?

How does the freeze drying process work in preserving food ?

How does the freeze drying process work in preserving food ?

Freeze drying is a process that dehydrates frozen foods placed inside a vacuum. The moisture in the foods converts into a gaseous vapour that leaves the food during processing. This removal of water content from frozen food is called sublimation. The freeze drying process allows the food to keep its original size and shape with minimum cell damage. Shrinkage is therefore eliminated or minimized and the food remains preserved for long periods in a near perfect shape. The freeze drying process is carried out in a special machine called a freeze-dryer, which has a large chamber for freezing and a vacuum pump for removing moisture.

The freeze-dried process was developed commercially in World War II when it was used to preserve blood plasma and penicillin for wounded soldiers. Freeze-dried coffee which was created in 1938 is the best-known freeze-dried product. Nestle company invented freeze-dried coffee called Nescafe and later other powdered food products were freeze dried. Over 400 different types of freeze-dried food products have been commercially developed since the 1960s. Although freeze-drying is used to preserve food in the 1970s agricultural crops such as peanuts and tobacco were also freeze dried.

Commonly heat is used in crop and food processing which alters the structure and chemistry of the product. The reason why freeze-drying is used is because it preserves crops and food the closest to the natural structure and chemistry. The process became popular when it was used to create freeze-dried ice cream which was taken into space as astronaut food. Freeze-dried food lasts longer than other preserved food and is very light weight, which makes it perfect for space travel. It is also widely used to produce essences or flavourings to add to food.

Steps in the freeze drying process

  • The food product is first frozen so that a condition can be created for low temperature drying.
  • After freezing the product is placed under vacuum. This enables the frozen solvent in the product to vaporize without passing through the liquid phase, a process known as sublimation
  • Heat is applied to the frozen product within the vacuum to speed up sublimation or removal of water
  • Low-temperature condenser plates remove the vaporized solvent from the vacuum chamber by converting it back to a solid.

The vacuum is maintained sufficiently high, usually within a range of about 0.1-2 mm Hg so that sublimation is done speedily. Heat is controlled in a way that does not melt the ice but allows the moisture to turn into vapour that leaves the food speedily. Sublimation or removal of water takes place from the surface of the ice on the frozen food. As the sublimation continues the ice recedes towards the centre of the food. This means that drying of the food takes place from the surface to the centre till moisture in the food is lowered to below 5 per cent. Since the frozen food remains rigid during sublimation, escaping water molecules leave voids behind them, resulting in a porous sponge like dried structure. Mostly heat used for sublimation is infrared and microwave radiations which make it easy to pass through already dried and porous food layers and then into the ice core.

Foods that are Freeze-dried

Freeze drying can be used to dehydrate sensitive, high-value liquid foods such as coffee and juices. It is especially used for drying high value foods such as strawberries, whole shrimp, diced chicken, mushroom slices, and sometimes food pieces as large as steaks and chops. These types of foods have special flavours and colours and textural appearances that cannot be preserved by any other current drying method except freeze-drying. A whole strawberry, for example, is soft, fragile, and almost water so cannot be preserved well unless it is freeze dried. Freeze dried foods are shelf-stable at room temperature for up to twenty-five years or more, if canned, and between 6 months to 3 years if stored in a poly-bag container.

The Benefits of Freeze-Drying

  • Freeze drying is considered and expensive process but is used at it makes carrying the food easy especially to space.
  • The food retains its original form, size, colour, taste, texture and nutrients
  • When placed in water the food regains its fresh flavour, aroma, texture, and appearance
  • Food has a long shelf life at room temperature and does not require a cold storage
  • The weight of the freeze-dried products is reduced by 70 to 90 percent, with no change in volume and so is easy to handle
  • Shipping costs are reduced because of the light weight and lack of refrigeration
  • Low water activity virtually eliminates microbiological concerns
  • Any type of food or ingredient, whether solid or liquid, can be freeze-dried

What Does Your Chewing Gum Contain?

Chewing gum with mint taste, isolated on white

Chewing gum with mint taste, isolated on white

Chewing gums are very popular in western countries like USA, Canada and the UK. It is also becoming very popular in developing countries like India, particularly amongst the student community. In fact, India, with its open market economy and upwardly mobile middle class, is embracing much of the western culture, including dietary preferences. The global market for chewing gum is currently valued at a staggering USD 30 billion!1

Types of Chewing Gum

Chewing gums come in various shapes & sizes, colors, tastes & flavors and of a variety of brand names. These include the following:

  • Mint flavored chewing gumsg. Wrigley’s Spearmint, Wrigley’s Doublemint; Eclipse Mints; Extra Mints etc.
  • Fruit flavored chewing gumsg. Juicy Fruit
  • Teeth-whitening chewing gumsg. Orbit White
  • Bubble gumsg. Hubba Bubba, Super Bazooka etc.

There are also various categories of chewing gum available nowadays that cater to various consumer needs. While the standard type is sweetened with sugar, the health-conscious opt for chewing gums made of artificial sweeteners. A special type of chewing gum is also available for smokers who are looking to quit smoking. This type of chewing gum is impregnated with nicotine. Some of these special types of chewing gums are given in Table 1.2

Table 1: Special Types of Chewing Gum

Function of Chewing Gum Active Ingredient Brand Name & Availability
Analgesic Aspirin Aspergum, North America
Increase of attentiveness Caffeine Stay alert, USA
Antacid Calcium carbonate Chooz, USA
Prevention of dental caries Chlorhexidine Hexit, USA
Xylitol V6, UK
Smoking cessation Nicotine Nicorette, India & various other countries
Nutrition Vitamin C Endekay Vitamin C, UK

Composition of Chewing Gum

Chewing gum is composed of Gum Base, Softeners, Sweeteners and Flavors. These are briefly discussed below.

Gum Base: Chewing gum used to be made from latex sap of the sapodilla tree, which was originally native to Central America. The sap was called chicle and formed the gum base. Other substances that were also used as gum base included beeswax and paraffin wax. However, nowadays, synthetic rubber such as polyethylene and polyvinyl acetate or a mixture of artificial and natural bases are used as the gum base. It is the gum base that makes the chewing gum “chewable”.3

Softeners: These are added to retain moisture and help prevent the gum from becoming hard. Common examples of softeners include glycerin or vegetable oil.

Sweeteners: These are added to gum to give it a sweet flavor. Usually, sugar or corn syrup is used as natural sweetening agents. There are a number of artificial sweeteners, but the most commonly used are xylitol, sorbitol, mannitol and aspartame.

Flavors: The flavor component of chewing gum provides long lasting, high intensity and high quality flavor. These flavouring ingredients are usually added last during the manufacture of chewing gums. The most common flavors include mint spearmint, menthol and fruit flavors.4

Lanolin – A Controversial Ingredient in Chewing Gum

Lanolin, from the Latin lāna (wool) and oleum (oil), literally means wool wax, is a yellow waxy substance secreted from the skin glands of wool-bearing animals such as sheep. Lanolin is an ingredient of chewing gum and forms a component of the gum base, and thus not declared explicitly by the manufacturers. Since this is commonly used in skincare products, using it as an ingredient of chewing gum is not only unhealthy, but also unethical and therefore highly controversial. Moreover, sheep sprayed with insecticides could lead to these toxic chemicals eventually entering the human body, and thereby causing adverse health consequences. Scientists are of the opinion that these insecticides could even enter breast milk and thereby transferred to babies of young mothers.5, 6

What Does the Codex Alimentarius Say?     

The Codex Alimentarius has prescribed maximal limits for various types of Food Additives in chewing gum. These are briefly tabulated in Table 2.7

Table 2: Maximum Levels of Various Food Additives in Chewing Gum as per Codex Alimentarius guidelines

Food Additive Maximum Level
Caramel Color, Class III 20000 mg/kg
Caramel Color, Class IV 20000 mg/kg
Fast Green FCF 300 mg/kg
Guaiac Resin 1500 mg/kg
Polydimethylsiloxane 100 mg/kg
Polyvinylpyrrolidone 10000 mg/kg
Stearyl Citrate 15000 mg/kg

 What Does the FSSAI Say? 8

FSSAI, the apex regulatory agency on food in India, has clearly stipulated that Chewing Gum or Bubble Gum should be prepared from chewing gum base or bubble gum base, natural or synthetic, non-toxic; cane sugar and corn syrup. As per the Food Safety and Standards (Food Product Standards and Food Additives) Regulation, 2011 (FSSR), there are 14 sources of gum base, including 8 natural sources such as natural rubber latex, natural resin, agar (food grade) etc.; and 6 synthetic sources such as synthetic rubber latex, synthetic resin, polyvinyl acetate etc.

The gum base can also contain milk powder, malt, chocolate, coffee, gelatin (food grade), permitted emulsifiers, purified water as well as nutrients like protein, vitamins and minerals.

The FSSR also specifies that the product must be free from dirt, filth, adulterants as well as harmful substances. The FSSR additionally recommends that the product must conform to the standards, as stipulated in Table 3.

Table 3: Chemical Composition of Chewing Gum/Bubble Gum

Ingredients Chewing Gum Bubble Gum
Gum Not less than 12.5% by weight Not less than 14% by weight
Moisture Not more than 3.5% by weight Not more than 3.5% by weight
Sulfated ash Not more than 9.5% by weight Not more than 11.5% by weight
Acid insoluble ash Not more than 2.0% by weight Not more than 3.5% by weight
Reducing sugars Not less than 4.5% by weight Not less than 5.5% by weight
Sucrose Not more than 70% by weight Not more than 60% by weight

As already discussed, since artificial sweeteners can also be used in chewing gum/bubble gum, the FSSR has recommended maximum limit for these additives too. These are listed below:

  • Saccharin sodium – 3000 ppm
  • Aspartame (methyl ester) -10000 ppm
  • Acesulfame potassium – 5000 ppm
  • Sucralose – 1250 ppm


These can also be added to chewing gum/bubble gum. Here also, the FSSR has fixed the maximum limits. For example, the maximum limit for the antioxidants Butylated hydroxyanisole (BHA) and Tertiary butylhydroquinone (TBHQ) is 250 ppm, while forTocopherol, it is 1500 ppm.


These include Benzoic acid and Sodium/Potassium benzoate, which can be present at a maximum limit of 1500 ppm. Other preservatives, such as Sulfur dioxide can be present at2000 ppm max., while Sorbic acid and its Calcium, Sodium and Potassium salts (calculated as sorbic acid) can be present at 1500 ppm max. Class I Preservatives as listed under Regulation 3.1.4 should be present as per GMP. 


These can be present singly or in combination, and include Sorbitol, Manitol, Xylitol, Isomalt,Lactitol and Maltitol should be present as per GMP.


These can be used singly or in combination within the specified limits but within the same class, i.e. either natural or synthetic.

Natural Colors: These can be present singly or in combination, and include Chlorophyll,Caramel, Curcumin or Turmeric, β-carotene, β apo-8 carotenal, Methyl/Ethyl ester of β apo-8 carotenin acid, Canthaxanthin, Riboflavin/Lactoflavin, Annato and Saffron, which should be present as per GMP.

Synthetic Colors and Inorganic Coloring Matter: These can be present singly or in combination. These include Erythrosine, Carmoisine, Ponceau 4R, Fast Green FCF, Indigo carmine, Brilliant Blue FCF, Sunset Yellow FCF and Tartrazine, which should be present at a maximum limit of 100 ppm. Titanium dioxide should be present at a 10000 ppm max.


These can be added singly or in combination. These include Natural flavor/Natural flavoring substances/Nature identical flavoring substances/Artificial flavoring substances, Vanillinand Ethyl vanillin, which should be present as per GMP.


These can be added singly or in combination. The only approved emulsifier for use in chewing gum/bubble gum is mono- and di-glycerides of edible fatty acids and should be present as per the regulation.

Alkalizing Agents

These can also be used singly or in combination and include Sodium, Potassium, Calcium,Magnesium and Ammonium carbonates. Of these, Calcium carbonate and Magnesium carbonate should be present as per GMP.

Neutralizing Agents/Acidulants

These include Phosphoric acid at 22000 ppm max as P2O5 and L-Tartaric acid at 3000 ppmmax. Besides these, Citric acid, Malic acid, L-ascorbic acid and Lecithin should be present as per GMP.


These include Talc and Mineral oil at 0.2%; Icing sugar, Glycerin, Paraffin wax or liquid paraffin (food grade) and Calcium, Magnesium, Sodium salts of Stearic acid (food grade) as per GMP. 


The only item under this category is Phosphated starch, which should be present as per GMP.


  1. Sugar-free Chewing Gum Drives Sales in the Global Gum Market. Market Optimizer. January 28, 2014. Available at Accessed on December 16, 2015.
  2. Adapted from the International Journal of Pharmaceutical Investigation. Available at on December 16, 2015.
  3. Helmenstine AM. What is in Chewing Gum? About Education/Chemistry. Available at Accessed on December 14, 2015.
  4. Chewing Gum Facts: Chewing Gum Ingredients. Available at on December 14, 2015.
  5. Cohen J. 6 Disgusting Things You’re Eating (And You Don’t Even Know It!). Forbes/Opinion. April 3, 2012. Available at Accessed on December 14, 2015.
  6. Sheep Wool Chewing Gum. Available at Accessed on December 14, 2015.
  7. Codex Alimentarius Commission. Report of the 31st Session of the Codex Committee on Food Additives and Contaminants, The Hague, The Netherlands, March 22 – 26, 1999. Joint FAO/WHO Food Standards Programme. Codex Alimentarius Commission 23rdSession, Rome, Italy, June 28 – July 3, 1999.
  8. Food Safety and Standards Authority of India, Ministry of Health & Family Welfare, Govt. of India. Food Safety and Standards (Food Products Standards and Food Additives) Regulation, 2011, dated August 1, 2011. Available at on December 17, 2015.

Why food manufacturers need to have a product recall system in place?

Recall Concept Egg in Nest Isolated on White with a Clipping Path.

Recall Concept Egg in Nest Isolated on White with a Clipping Path.

Product recall‖ means action taken to remove a marketed food product from distribution, sale and consumption that may pose a safety hazard to consumers. This means that the manufacturer has to ask for a return of a batch or the entire run of a particular product because of safety concerns. Product recall is usually very expensive as it requires the manufacturer to replace the recalled product or pay for any damage that could have occurred because of use of a defective product.

A food product is recalled so that the manufacturer can take corrective action needed to protect consumers from contaminated, adulterated, or misbranded product. A corrective action usually involves destroying replacing, or altering the product. The type of recall of a product depends on the company‘s food safety policies, ethical understanding, regulatory requirements, and financial constraints. A product recall is of two types

  • Voluntary recall is based on the decision of the management of a manufacturing company to recall the product. A product recall initiated by the manufacturers themselves limits the liability if the manufacturer has been negligent. It prevents further damage to the brand and improves the trust in the manufacturer to some extent. . If the recall is conducted smoothly then it can save the company from negative publicity.
  • Recall can be initiated by a government agency responsible for the particular product category in which case it will request the company to recall the product. The government agency can force the company to recall potentially misleading and/or hazardous product from distribution and marketing.

Food product recall according to Section 28 of the FSSA

In voluntary food product recall a manufacturer, either of its own through any other sources viz. wholesaler, distributer, retailer, exporter, importer, consumer, media etc., coming to know that any of its products is unsafe or deficient violating provisions of the Act and Rules, & Regulations made there under, may initiate a recall. In such situations, the manufacturer is required to submit a recall alert notification to the Competent Authority. To ensure speedy communication, such alert can be sent by Fax, e-mail, On-line and / or by post.

If the recall is government initiated then the Food Authority may direct the manufacturer to initiate a recall if a food product manufactured and distributed by him poses a health hazard or is in violation and the firm has not initiated a recall on its own. Seizure or other court action may be taken when a firm refuses to undertake a recall directed by the Authority or if the Food Authority has sufficient reasons to believe that

  • recall would not be effective,
  • determines that a recall is ineffective
  • discovers that violation is continuing

The cost incurred by the Food Authority for carrying out such actions will be recovered from the firm responsible for such violation.

Purpose and goals of the recall plan 

A product recall cannot be worked out hastily when the crisis strikes. It should be a part of the company’s FSMS programme if the manufacturer wants to lessen the impact of the product recall. A recall is undesirable because besides being expensive it brings about negative publicity. However, if a recall is required then is important to be ready for the recall and it is in the company’s best interest to complete it as quickly as possible. If the recall needs to happen smoothly and quickly there has to be a recall plan in place. For this the management of the manufacturing company has to be a part of the recall plan and team so that the recall is effective.  This will allow the company to avoid or improve on negative publicity. A plan will allow the company to cover the expenses that a product recall will require. A recall plan should be able to achieve the following goals

  • Protect consumer health
  • Comply with existing FSSA rules and regulations
  • Minimize the cost of the recall
  • Regain and improve the company‘s reputation

According to FSSAI “all food businesses engaged in the wholesale supply, manufacture or importation of food regulated by Food Authority must have an up-to-date recall plan except food retailers, unless they are also engaged in the wholesale supply, manufacture or importation of food. Food businesses within the food service sector such as restaurants, caterers and takeaways are exempted to have recall plan unless they are running multi-outlet food business chains having integrated manufacturing and distribution network.” 

A Successful Recall Process 

  • A successful recall process depends on planning of the recall management well before a problem occurs.
  • Time is an important factor and the sooner the recall is initiated the less harm is will cause and lessen negative publicity
  • Communication needs to be effective during a recall so that everyone in the product distribution channels can act on the instructions. Public notification about the recall through press releases and specialized media is also an important aspect of a recall process.
  • Post-recall assessment is as important to determine if the recall has been effective and to improve on any shortfalls in any future recalls if they should occur.

Management’s responsibility in food product recall

Without the involvement of the management in the product recall the recall procedure will not be swift or effective or completed in a timely manner.

The top management of the company should

  • appoint personnel having the authority to initiate a recall and personnel responsible for executing the recall
  • establish and maintain a documented procedure for notification to relevant interested parties (e.g. statutory and regulatory authorities, customers and/or consumers),
  • handle recalled products as well as affected batches of the products still in stock, and the sequence of actions to be taken

All recalled products need to be kept securely or held under supervision until

  • they are destroyed
  • used for purposes other than originally intended
  • determined to be safe for the same (or other) intended use
  • reprocessed in a manner to ensure they become safe

The management must be made fully aware of the causes and the extent and result of a product recall. Any recall must be recorded and reported to top management. This will provide an input to the management so decisions can be taken to prevent recurrence. The company must verify and record the effectiveness of the recall programme through the use of mock recall programmes.

In class suit, NCDRC seeks more tests on Maggi for Lead and MSG content

Tuesday, 29 December, 2015, 08 : 00 AM [IST]
Ashwani Maindola, New Delhi
The National Consumer Disputes Redressal Commission (NCDRC) has sought more tests on Maggi noodles in the class suit case filed by the consumer affairs department. In a hearing held earlier in December, the apex consumer rights body had sought the tests to be carried out at the Export Inspection Agency, Mumbai, while the next hearing would be scheduled on January 12.

In its direction, the commission stated that the samples would be tested and analysed for Lead and MSG content. The commission stated in its direction that the Export Inspection Agency within two weeks of receiving the said samples report the quantity if any of the Lead and MSG found in Maggi noodles and the tastemaker to it at the earliest.

Meanwhile, the test results of the earlier samples that were sent to the CFTRI (Central Food Technological Research Institute) Lab in Mysore were yet to come and the matter has been listed for the next date by which the same was likely to come.

The government had earlier sought fresh tests on Maggi samples in a government prescribed lab. The department of consumer affairs, in an application, was seeking testing of 50 samples of Maggi noodles out of a large number of packets seized by Food Safety and Standards Authority of India (FSSAI), to an appropriate laboratory.

Nestle opposed the move during the hearing. According to sources, Nestle’s counsel stated that though the company does not add any MSG to Maggi noodles, the regulations do permit its addition in various foods and in the seasoning for instant noodles and therefore, testing for MSG will be a futile exercise.

It was also claimed, during the hearing by Nestle, that though it was possible to test the presence of glutamic acid and glutamates, it was not possible to distinguish, through analysis, whether glutamate was in free form or bound with sodium or other salt, and since glutamic acid and salts of glutamate were naturally present in the foods, the testing for the presence of glutamate irrespective of whether it was in free or in bound form and other salts of glutamic acid, would be a futile exercise because the result would always show positive for the presence of glutamate.

Further it was argued that CFTRI had already tested the product sent for testing by FDA, Goa, and found it compliant and therefore the request for further testing appeared to be a fishing experiment, in an attempt to give life to a case which could not stand. Further argued by Nestle’s counsel that in terms of direction of Bombay High Court, 90 samples were collected covering six different available variants and were sent to independent accredited laboratories notified by FSSAI for testing of the Lead parameter. Also a similar request for sending samples in possession of the authority has already been rejected by the Bombay High Court.

But the commission in its observation stated, “In our opinion, it would only be appropriate that the samples in terms of this order are examined by a government laboratory. We therefore, direct the samples sealed and authenticated in terms of this order to be tested and analysed by Export Inspection Agency, Mumbai, at E-3, MIDC area, Marol, Andheri (E), Mumbai-400093.”

New Year parties under FDA’s check

All the big parties that will happen on the New Year’s Eve across the city can expect the Food and Drug Administration (FDA) department check their platters. The FDA will collect food samples served at restaurants and inspect its quality to see if it is in line with the standards set by Food Safety and Standard Authority of India (FSSAI).
Last year, the FDA inspected about 174 food samples of which only 2% served eatables that didn’t comply with the FSSAI standards.
The department also urges party goers to be aware of the quality of foods they are being served.

In Bhopal, gyms, wellness centres wink at FSSAI norms

BHOPAL: A horde of macho men associated with gyms and wellness centres in Bhopal go all out extolling power of protein powder energy drinks and supplements. And many do not bother registeration with Food and Drugs Administration (FDA).
District health officials are yet to wake up to side-effects of youngsters aspiring to bulk up like a pro. The risk is real and potent, said district chief medical and health officer (CMHO) Dr Veena Sinha. “There can be unwanted side-effects from using unregulated power supplements. There are certain physical conditions that require advice from medical practitioners,” she said. “We will pursue with these centres to register as per norms in keeping with public safety,” she said.
On Friday, senior IPS officer S K Pandey died of heart attack during a workout in a posh gymnasium. The incident has once again brough into focus an urgent need to regulate and monitor wellness and health centres.
As per information from FDA, none of the body building or wellness centres in the state capital are registered as per Food Safety and Standards Authority of India (FSSAI) rules. District health office, however, claimed one centre was registered in nearly two years since the directive was issued.
As per government circular, health centres should register with the office of CMHO under the Nursing Home Act. As per new directives, fitness centres will have to obtain licence from CMHO. Health officials will conduct surprise inspections and test supplements being supplied by these centres.
As per directives, owners of gyms, spas and other fitness centres should submit a list of documents, including health status of their employees to get a licence. Physiotherapy centres will also be covered under the new rules.
Experts said there are chances of bacterial infections and spread of diseases like hepatitis in a gym. The centres would also have to provide clean drinking water and toilet facility.
“In past, FDA collected samples of nutraceuticals. However, registration of these centres is mandatory as per law,” said MP-FDA joint controller Pramod Shukla.

Only ‘expiry date’ for food items, not ‘best before’: Paswan

Hyderabad: The Union Minister Ram Vilas Paswan on Sunday said labels printed on food items should carry only “expiry date”, and not “best before”, which has no meaning.”We want that only there is ‘expiry date’. There is no meaning in ‘best before'”, Paswan, the Consumer Affairs, Food and Public Distribution Minister, told PTI here.

Paswan said he would convene a meeting of his department to “work out” and implement this measure.
National Consumer Disputes Redressal Commission (NCDRC) President D K Jain said last week consumers get confused about labels printed on food items and the Food Safety and Standards Authority (FSSAI) should look into labelling issues related to ‘expiry date’ and ‘best before’.
Jain had wondered if ‘best before’ label means it is fit for human consumption after six months.
Paswan also said the Centre is in discussion with National Association of Street Vendors of India vis-a-vis earmarking certain areas in cities for selling of such good.
“We want a system for (selling of) street food. We want this activity to take place in particular place”, he said.
Paswan noted the people enjoy food in “dhabas”. Similarly, street food can also be safe and cheap and can be sold in an enjoyable atmosphere.
Noting that the Association had held a “mela” in “Dilli Haat”, Paswan said such an initiative, whereby certain areas are earmarked for street food, should be implemented in other places in the country.