A study into the use of Freeze-Drying as a method of food preservation
Student name: Roseanne Brennan
Student number: C17751591
Course: Baking and Pastry Arts management
Year: DT418/1
Module: Introduction to Culinary Science: TFCS 0021
Lecture: Therese Cadden
Assignment brief: Select one method of food preservation and discuss in detail.
Submission date: 16th April 2018
Table of contents:
1.Introduction”….pg.3
2. Aims and Objectives’pg.3
3.1. Ancient history of freeze-drying”.’pg.4
3.2. Modern history of freeze-drying’. pg.4
4. Modern uses of freeze-drying technology.pg.5
5. The process of freeze-drying’. pg.5
6. Conclusion”…pg.6
7. References’pg.7
1.Introduction
This study was written to discuss in detail, the use of Freeze-drying as a method of food preservation. Through research of various sources, it has become apparent that freeze-drying food produces a better tasting and longer lasting product in comparison to the older methods of simply drying foods. The main difference between the two, is that freeze-drying has the ability to subtract a higher volume of the water content in material which makes it last longer as it makes it harder for harmful microorganisms to grow without moisture. Due to the lack of heat being applied the materials original composition remains the same as it is being freeze-dried thus, giving a much better taste and structure when rehydrated.
2. Aims and objectives
1 To discuss a brief history of ancient and modern methods of freeze-drying
2 To explain what freeze-drying is
3 To discuss the process of freeze-drying used today
4 To discuss modern uses of freeze-drying food products
‘To freeze-dry, is to preserve (something) by rapidly freezing it and then subjecting it to a high vacuum which removes ice by sublimation.’ (Oxford English dictionary, 2017)
3.1 History of freeze-drying
Sources claim that freeze-drying to preserve food was used by the ancient Chinese and Peruvian Incas. It is said that the Chinese would hang their meat outside in the cold winter weather so it would freeze. They would then dry the meat. It is believed they did this to enhance flavour and prolong shelf life. While sources say the ancient Incas would freeze their crop high up in the mountains, and due to the low pressure of the high altitudes, the water within the crops would slowly sublimate, thus preserving their crops in a similar way we know today. (Hua, Liu and Zhang, Page 2, 2010)
3.2 Modern history of freeze-drying
The modern use of freeze-drying, also known as Lyophilisation, is dated back as little as 88 years ago. One of the first major breakthroughs has been credited to the company,’ Nestle’, in 1930. Their chairman was approached by The Brazilian Coffee Institute and asked to create a coffee that would be soluble in hot water while still holding its flavour. It took seven years of research by the company’s research centre before scientist, Max Mortgenthaler, invented freeze-dried coffee. Another breakthrough that has received credit for the development of freeze-dry technology is in 1933. Two scientists from the university of Pennsylvania were able to preserve human serum by freeze-drying it using glass equipment. (Hua, Liu and Zhang, Pg.1 & 2, 2010)
4. Modern uses of freeze-dry technology
Due to the surge in development of technology in the modern age, freeze-drying has become more developed and we use it for many reasons today, mainly convenience. Freeze-dried food has been used as Astronaut food in the form of freeze-dried powders, fruit and vegetables. Available in many combinations of flavours, the Astronauts use the oven and water provided on board to rehydrate the food while they are in orbit. (NASA – Food for Space Flight, 2009) While these meals might not be the most appetising in comparison to a home cooked meal, they provide the Astronauts with the nutrients and energy to stay healthy while in space while optimizing the small space they have on the space craft.
Freeze-dried foods preserve their flavour. This makes freeze-dried fruits popular in the cereal industry and can be found in cereals like, ‘Special K’. Due to the removal of 96%-99% of the water content, it makes freeze-dried food significantly cheaper to transport as they are light in weight.
5. The process of freeze-drying
The basic idea behind freeze-drying is to maintain the composition of the material by converting the water content present in the material directly into water vapour. This means heat is not necessary as it is in when ‘drying’ food and the composition and structure is not affected at all. This gives a much better quality dried material and is the reason for its growth in popularity today, combined with new technology available. Essentially, a product is frozen, then using a vacuum space at low temperature the product is dried by sublimation drying till 95-99% of moisture is removed. (Meller, 1967). The freeze-dried product can then be stored at room temperature or low temperatures for a long period of time. By maintaining the products composition, this ensures flavour remains in the product.
Photo credit: https://www.slideshare.net/bknanjwade/drying-53262955
6 Conclusion
To bring the study to a conclusion, it has been shown that freeze-drying food, although only regarded as a newer developed form of food preservation, can have multiple uses to us in the modern day. Removing the water almost completely significantly slows down the rate of growth of harmful microorganisms which makes freeze-dried food perfect for potential long trips making it handy for astronauts and those in the army to have food that is easily transportable and has a long shelf life. It has also been shown that freeze-fried fruit are popular in the cereal industry as the flavour of the fruit is still maintained when hydrated. Extra costs are not added either due to the low cost of transport because of how light the freeze-dried fruit is.
References:
‘ NASA – Food for Space Flight, nasa.gov., https://www.nasa.gov/audience/forstudents/postsecondary/features/F_Food_for_Space_Flight.html, 13th April 2009
‘ J. D. MELLOR FREEZE-DRYING 'PROCESS, https://patents.google.com/patent/US3352024A/en, November 14th, 1967,
‘ freeze-dry | Definition of freeze-dry in English by Oxford Dictionaries, Oxford Dictionaries | English, https://en.oxforddictionaries.com/definition/freeze-dry, Accessed 13th April 2018.
‘ Tse-Chao Hua, Bao-Lin Liu, and Hua Zhang, ‘Freeze-drying of pharmaceutical and food products’, Woodhead Publishing series in food science, technology, and nutrition. Pages 1&2, 30th July 2010.)
Other websites that aided research:
‘ https://csiropedia.csiro.au/food-and-nutritional-sciences-2010-2012/
‘ https://www.nasa.gov/audience/forstudents/postsecondary/features/F_Food_for_Space_Flight.html
‘ https://science.howstuffworks.com/innovation/edible-innovations/freeze-drying1.htm