food product development consultants

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ISOCHORIC FREEZING?
New Technologies Report - 04? Date 4th
November , 2022?
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INTRODUCTION

• Freezing is a food preservation technique that
  involves decreasing the temperature to stop
  bacterial growth. The technique of freezing food
  by submerging it in an ice and salt brine has
  been followed for millennia in cold climates, and
  a patent for it was granted in Britain as early
  as 1842.?
• Over the years, several freezing technologies
  have been evaluated for preserving food and other
  biological matters. Such as-?

• 1.Freezing by Contact with a Cooled Gas.?
• It is known by many names, such as cabinet
  freezing, air-blast freezing, belt freezing,
  spiral freezing and tunnel freezing.?
• 2.Cryogenic freezing ?
• Liquefied gases directly contact the foods in
  cryogenic freezing 1.?

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EMERGING TECHNOLOGY
Frozen via Isochoric System
Fresh Spinach
Commercially Frozen

• ISOCHORIC FREEZING?

• Isochoric is an alternative preservation
  technique developed by Rubinsky and his group.?
• Isochoric freezing preserves food products at
  sub-freezing temperatures without ice formation
  inside the product. ?

• Why is it different from other methods ?

• The food product is immersed in an isotonic
  solution and brought to a sub-freezing
  temperature inside the closed chamber.?
• During freezing, ice expands in volume,
  increasing the pressure.?
• However, some volume remains unfrozen due to the
  Le chatelier's principle.?
• A chamber is designed for food in a non-frozen
  section, then preserved at sub-freezing
  temperature without internal ice formation.?
• This separation from ice and food is impossible
  in the conventional freezing process.?

Roberto Avena-Bustillos (left) and Cristina
Bilbao-Sainz demonstrate the use of isochoric
freezing chambers. Photo courtesy of the U.S.
Department of Agriculture 2
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In a typical Isochoric process,

• The food material is immersed in an isotonic
  solution inside a rigid container capable of
  withstanding elevated pressure.?
• Materials such as stainless steel cylinders,
  carbon fibre composites, and hard phenolic
  thermosets with pressure transducers and rupture
  disks are employed for isochoric processes.?
• Then, ice crystals are introduced into the
  container as the nucleation site, and the chamber
  is tightly packed.?
• Inserting this nucleator to preserve food
  materials in their aqueous phase without forming
  ice crystals is essential.?
• The chamber is then sealed with a metal screw to
  restrict any air passage in and out of the
  container 3. ?

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PRESERVATION OF GRAPE TOMATO BY ISOCHORIC
FREEZING ?

• By Cristina Bilbao-Sainz et al., 2021?
• This investigation looked into tomato
  preservation using isochoric freezing.?
• Isochoric freezing was compared with freezing
  under isobaric conditions and with methods of
  food preservation at 10oC cold storage and quick
  individual freezing (IQF).?
• The nutritional and physicochemical qualities
  were assessed. ?
• The findings indicate that it is possible to
  preserve tomatoes by isochoric freezing while
  keeping their physicochemical and nutritional
  qualities close to those of fresh tomatoes, which
  may have applications in the industrial
  preservation of tomatoes 4 5.?

Fig 1 Photograph of fresh grape tomato and
preserved tomatoes after four weeks 4
Fig 2 Schematic of an isochoric system (two left
panels), photograph of the isochoric system,
right panel 5
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IMPACT ON ENZYME?

• The isochoric method helps lessen food browning.
  When potatoes were kept at 5 C under isochoric
  refrigeration as opposed to isobaric freezing,
  there were noticeable differences in their
  colour.?

FOOD QUALITY IMPACT?

• A constant-volume preservation method in a closed
  rigid container can better retain the food's
  quality. For instance, potatoes lose weight at
  the same temperature in an isobaric freezing
  system. In contrast, when stored in an isochoric
  refrigeration system (5 C) system immersed in a
  10 (w/w) sucrose solution, potatoes experience
  no weight loss.?

A comparison of freezing-damage during isochoric
and isobaric freezing of the potato? 3. 

• Escherichia coli was shown to suffer from
  membrane damage, changes in the size and form of
  the cell, protrusions, ruptured membranes, and
  the outflow of intracellular materials after
  being isochoric-cooled to 15 C.?

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FUTURE PROSPECTS

• Further research needs to be done on
  commercialisation since some products under high
  pressure have a detrimental effect.?
• Studies need to be done to understand the
  mechanism by which delayed enzyme activity
  occurs. Similarly, the effects on micro-organisms
  need to be studied ?
• The focus of engineering research currently must
  be on simpler designs establishing procedures for
  extensive use.?
• Improvements must be made in process economics
  3.?

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NEWS
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REFERENCES

• https//www.sciencedirect.com/science/article/pii/
  B9781782424475000071?
• https//www.ift.org/news-and-publications/food-tec
  hnology-magazine/issues/2019/november/columns/isoc
  horic-freezing
• https//link.springer.com/article/10.1007/s12393-0
  21-09284-x
• https//www.researchgate.net/publication/349743182
  _Preservation_of_grape_tomato_by_isochoric_freezin
  g
• https//www.ncbi.nlm.nih.gov/pmc/articles/PMC54385
  86/

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THANK YOU
M1. 20