54
DEC 2017
FOOD FOCUSTHAILAND
SOMETHING
ABOUT FOOD
LyophilisationProcess
Initial process for freeze drying is similar to the production of any dried
food. It starts with preparing the raw material to be in an appropriate
condition suchaswashing, peeling, resizing, thenproceed into themain
process consistingof 3 steps;
1. Freezing -
this process reduces the food’s temperature to below
freezing point to create ice crystal formation. In order to create small
crystals, the freezing rate should be a rapid procedure, for example, air
blast freezing, cryogenic freezing, and immersion freezing.
2. PrimaryDrying -
this dehydrationprocess is doneby sublimation
and reducingenvironmental pressureat vacuum level below132Pa -132
mPa, inorder to reducewater from theproduct’ssurface.Thesublimation
of ice layer starts from the surface, whichmakes this layer a “dry layer”.
The followingdehydration step is the sublimationof water (in solid state)
inside the products. The sublimation time depends on the size, shape,
and structure of the product.
3. SecondaryDrying -
after the primary drying is completed, all ice
should be sublimed. Nonetheless, there could be somemoist remained
in theproduct.Here, the temperaturemustbe increased inorder to remove
the remainedmoist to a safe level for storage.
Advantagesof FreezeDriedTechnology
Lyophilisationor “Freeze-dried” technology is considerably thebest food
preservation method existing at the moment, because it does not give
foodany heat during theprocess. Its principle relies on theabsorptionof
water from theproduct,hence theprocess isconducted in low temperature
which reduces the lossof food, for instance, tissuedamageanddestruction
of foodstructure,due toheat.The result is thatwegetexcellentdried food
withgood rehydrationand sustainedqualities - colour, aroma, taste, and
texture - compared to food processed by other technologies like spray
drier, tray drier, and cabinet drier. Although, freeze drying is somewhat
more costly than hot air drying. Therefore, it has the ability to maintain
almostallof the the food’squalityandnutritionandprolongshelf lifewithout
altering thenature of the food, which bares some advantages as follow;
1.Maintainbasicqualitiesandphysicalpropertiesof the food, including
colour, shape, size, flavour, texture, and nutritional values.
2.The foodcan return to itsoriginal form,withoriginal qualities,when
it receiveswater ormoisturise
3.The food remainsunrottenbecause it has less than3%ofmoisture
content (no bacteria growth)
4.Product canbekept in room temperature forat least 1-2years, and
is not required tobe stored in freezer to avoid decaying.
5. Product’sweight decreases 70-90% though no tissue is lost
6. Product’s lightweight makes it easy to be transported and kept
7. Logistics cost is reduced because freezer is unnecessary and the
product is lightweight
8. Product’s quality iswell-preserved comparing to othermethods
9. Nowater content in the food, whichmeansnoneed to concern for
microbes
10. Freeze dried can be used for everything, either food or food
ingredients, and either solidor liquid
11. Freezedrying technology canbeused inpreparing for bacteria’s
leavening agent in order to preserve it for a long time
12. The technologycanalsobeused toprepareproteinsubstance
for long shelf life
13. Fresh flowers, fruits,meats, andany instant products canuse
thismethodwithhighefficiency
Typesof FoodProductsUsuallyFreezeDried
FreezeDriedFruits
The hottest product at the moment is freeze dried durian, especially
Mon-Thong, which is in high demand for the export market and from
tourists.Apart fromdurian, thereareother fruits that canalsobe freeze
dried such as mangosteen, longan, rambutan, jackfruit, pineapple,
strawberry, etc.
FreezeDriedFreshVegetables
Freeze dried vegetables bare outstanding quality of long lasting shelf
life, uneasy to rot, but very convenient to use. Youwould only need to
add hot water or boil it when you need. Most of the vegetables freeze
driedareseasonalproductswhichareexpensiveduringsomeoccasions,
for instance coriander, spring onion, kale, corn, spinach, and okra.
FreezeDriedCoffee
Instant coffee is a drink that coffee drinkers consume every day and
freezedried technology canhelp inpreserving the flavour, aroma, and
quality of the fresh coffee. Here, coffee beans are roasted, grounded,
andmixed intoa liquid form.Theproduct thengoes through lyophilisation
and come out as flakes which can be stored and instantly mixed
anywhere, at anytime.
FreezeDried InstantMeal
In countries where food is difficult to find or expensive, some people
prefer ready-to-eat meal because it is easy to find and inexpensive.
Freezedried technologycanbeagreat help inpreserving the foodand
maintaining its deliciousness, while adding the convenience and
portability to theproduct. Freezedried instant food iseasy toeat, - just
open, addhotwater, or steam for a fewminutes - thenyouwill have the
closestsimilarityof the freshlycooked food.Popular freezedried recipes
are Tom Yum Kung, Pad Thai, green curry, Somtam, Tom Kha Gai,
chicken massaman, durian sticky rice, and mango sticky rice, for
example.
FreezeDriedMeats
Freeze dried technology can reduce 60% of the freshmeat’s weight,
whichmakes itmucheasier for exporter toshipandcontrol theproduct
as it does not need tobe stored in cold roomon the logistics ship for a
long time. Freeze driedmeats are pork, shrimp, squid, and surimi, for
instance.
เอกสารอ้
างอิ
ง/References
-การทำ
�แห้
งแบบแช่
เยื
อกแข็
ง
FreezeDriedTechnology
GettoKnowtheTechnology
andBenefitsofFreezeDrying
Lyophilisationor “freezedried technology”means thedehydration,
by freezing, tochangewater tosolidphase, thenapplysublimation
process to transform water from solid phase to gas phase by
decreasingsurroundingpressure to lower thannormalatmosphere
while controlling low temperature (to be equal to 0
o
C as ice
sublimation at a pressure of 4.7mmHg or less).
