1) What are the different types of Potato and at what temperature are they stored?
There are typically 2 types of Potato Cold Store :
(a) Sugar Potato - Temperature maintained is 2 to 4 °C
(b) Potato Seeds (Sugar Free Potato) - Temperature maintained is 8 to 12 °C
2) Confused between Ammonia and Freon?
Following is our recommendation:
(a) For Total Cold Storage size of 2500 MT and below, you can prefer Freon
(b) For Total Cold Storage size of 2600 MT and above you can prefer Ammonia
● Capital Cost is almost the same for both
● Operational cost for ammonia is lesser when compared to freon for 2600 MT & above
● Automatic running of machines is beneficial and requires no maintenance for 2500 MT & below since no operator is required
3) How to decide choosing between Bunker & Units Cold Storage?
Advantages of Unit Coolers over Bunker System:
(a) Bunker is a traditional technology to cool Potato while Units is a more modern and efficient Technology to cool Potatoes
(b) Hot spot Creation - There will be more number of hot spots in a bunker Cold Storage as compared to a Unit Cold Storage
(c) Space Saving - Bunker consumes a lot of space when compared to a Unit Technology. One can keep an additional 5,000 to 6,000 bags of 50 kg Each in a Unit Cold Storage
(d) Uniformity of air -There is proper circulation of air in a Unit Cold Storage
Advantages of Bunker Technology over Unit Technology:
(a) When a single chamber exceeds more than 3500 MT of material, Bunker technology is better.
4) What is refrigeration capacity (Heat Load) for a potato cold storage?
The Refrigeration Load of Potato Cold Store consists of Mainly 2 types of Load:
(a) Heat Load at the time of Loading
(b) Heat load after the loading
At the time of the loading, the Refrigeration capacity is very high. The reason behind this is temperature of Potato has to be brought down from Ambient to 2 °C within 15 days to increase the shelf life of the Potato After the loading, the Refrigeration capacity is comparatively low. The temperature only needs to be maintained at 2 °C or 10 °C depending on the type of potato.
The following parameters are required to design Refrigeration System for Potato Cold Storage
(1) No. of Bags per Chamber
(2) No. of Chambers
(3) Outside Temperature
(4) Weight of Each Bag
(5) Total Storage Capacity
(6) Chamber Size
(7) Loading Temperature
(8) Loading Rate
(9) Air Cooled / Water Cooled
For a typical 5000 MT Potato Cold Store, the Refrigeration Capacity required is 120 TR @ -5 °C Evaporation Temperature
5) What are the factors to keep in mind while designing the Indoor unit for a potato cold storage?
There are various factors which need to considered at the time of designing a potato cold store unit:
(1) Air Volume - Total air volume should be minimum of 85 cmh per ton of material during loading period at static of 100 psi
(2) Surface Area - Total surface area of the evaporator
(3) Air Throw - Should be minimum or more of the room length or width (depending on the side in which the units are placed)
(4) Relative Humidity - Unit should be designed optimally to give adequate Relative Humidity in the Chamber
(5) Fin Spacing - Should be 4 FPI or 6 mm
(6) Fan kW or Hp - To be considered while designing the Unit
(7) Pitch of the Evaporator - Square Pitch. Best design to have less pressure drop and better efficiency and as a result lower power consumption
These factors can affect the following in the cold store:
(a) Electricity consumption
(b) Quality of potato
(c) Weight loss
(d) Avoiding creation of hot spots
(e) Optimum utilization of space in the cold storage
6) How to keep potato quality high and less weight loss in a potato cold storage?
Selection of right indoor & various factors in selection of indoor - answered in question no. 5
7) What are the ways in which electricity consumption can be reduced in a potato cold storage?
There are various ways Total Electricity consumption can be saved:
(a) You may prefer the following PUF panel considering density of 0.4kg/m3 as per the below temperature:
● 7° C to 25° C: 60 mm
● 0° C to 7° C: 80 mm
● (-) 15° C to 0° C: 100 mm
(b) Proper Selection of Indoor Units
(c) Roof Insulation
(d) Leakages in Insulation
8) What role does the indoor unit play in saving electricity?
(a) Indoor unit is approx 25% of the total electricity consumption in a cold Storage. Hence, designing & selection of the evaporator plays a big role in saving electricity (Refer to question 5)
(b) Choosing the right pitch (we recommend for square pitch) of the evaporator plays a major role
(c) Since the other factors like compressor, ammonia pump & condenser pump are all fixed the only way to save electricity is through right selection of Indoor units only
(d) The right balance of pitch, surface area, air volume & tube volume in the indoor unit will help in saving electricity
9) How important is air flow for the quality of the product?
(a) Air Flow plays a major role in the quality of the product. It is recommended to have 85 cmh of Air inside the room during loading period
(b) If the Air Flow is not adequate in the room, there will be a potential of creation of hot spot inside the chamber & will result in sprouting on the potato
(c) To avoid Hot Spot Creation inside the room (like corners, bags kept at the end of the chamber) air flow plays a major role
10) What is the importance of air throw in a potato cold storage?
It is important that the air reaches at all ends in the Cold Store in order to keep the Potatoes fresh even after a few months. Hence, air throw from evaporator should be at least the equal distance of room length or width (as per design)
11) How to avoid hot spots in the potato cold store?
Refer to question No. 10
12) How do you avoid sprouting on the Potato?
Refer to question No. 5
13) What are the storage conditions of potato?
Temperature: 4.4 °C to 10 °C
Storage period: 0 to 3 months
Relative humidity: 95%
14) What are the dependent factors for potato storage?
a) Type of end use (seed, table, or processing)
b) Disease incidence
c) Risk of sprouting
d) Degree on variety
15) How to handle newly harvested potato?
a) Newly harvested potatoes are held at moderate temperature 10 °C to 15.6 °C and humidity of 95%
b) Good aeration for 10 to 14 days after harvest to complete the wound healing / curing process
c) At temperature above 16 °C high tuber respiration rates become a concern one if the tubers are to be held for long term storage
16) What are the general practices for potato?
a) Seed potatoes – the temperature may be lowered to 3 °C where dormancy will persist in definitely
b) Table potatoes – usually stored at 4.4 °C to 7 °C. At lowest temperature a noticeable sweet flavor occurs due to conversion of starch to sugars
c) Processing potatoes – French fries stored at 7 °C to 10 °C, chipping stored at 9 to 13 °C and dehydrated stored at as same as French fries condition
17) List out the major diseases and disorders of potato?
a) Alternaria tuber rot
b) Bacterial ring rot
c) Black heart
e) Freezing injury
h) Transit bruising
18) List the quarantine diseases of potato?
a) Cyst nematode (Globodera spp.)
b) Viruses and viroids
c) Brown rot ( pseudomonas solanacearum)
d) Ring rot ( corynebacterium sepedonicum)
e) Powdery scab (spongospora subterranean)
19) What are the forms in frozen product of potato?
f) Hash browned
h) Cake forms
20) List the factors affecting the quality of potato in freezing purpose?
c) Growing location
d) Harvest condition
e) Storage management
21) What is the storage condition for frozen product of potato?
a) For long term storage, should maintain at -18 °C will deteriorate less and maintain quality
b) Frozen French fries held at -21 °C for at least a year with little loss
22) What are the practices for dehydrated product of potato?
a) Potatoes contain about 80% water. During dehydration total solid ratio increase by 4 to 5 times
b) Vacuum packing also aids in the extension of shelf life
c) Dehydrated product should be stored at 7 °C, even if vacuum packed
d) If stored for longer periods, dehydrated product should be held at lower temperature