Block Ice, Tube Ice or Flake Ice: Choosing an Ice Plant for Fish and Produce

Ice is the cheapest cold-chain tool there is, and for a lot of Bangladeshi fish traders, landing centres and produce handlers it is the only one available at the point of catch or harvest. But “an ice plant” is not one machine. Block, tube and flake ice are made differently, behave differently in a fish box, and suit different buyers. Choosing the wrong type means either ice that melts before the fish reaches market or ice that bruises the produce it is meant to protect.

Block ice: slow, dense, made for the boat

Block ice is frozen in large cans immersed in a brine tank, taking many hours to freeze solid. The result is a dense block with a small surface area for its mass, which is exactly why it melts slowly. For a fishing boat going out for days, or a long unrefrigerated truck run to an upcountry market, that slow melt is the whole point — the ice lasts the trip.

The trade-off is that a block cannot touch fish directly and cool it fast. It has to be crushed first, which means a crusher at the landing point and the labour to run it. Block plants also take longer to produce a given tonnage and need brine handling. For operators whose problem is holding time in the field with no power, block ice is still the right answer despite the extra step.

Tube ice: clean, hard, easy to handle

A tube ice machine freezes water on the inside of vertical tubes and then releases it as short hollow cylinders. The ice is hard, dry, relatively slow-melting for its size, and made from clean water in a closed system, so it is the type you see bagged for drinks, hotels, and anywhere the ice has to look and be hygienic. Production is continuous and automatic, with no brine.

For fish, tube ice cools reasonably well and packs into a box without bruising, and its slower melt beats flake ice on a longer haul. It is less aggressive at pulling heat out fast than flake, and the pieces have gaps, so a box iced with tubes has less ice-to-fish contact. It is a good general-purpose choice where the same plant serves both food service and produce.

Flake ice: maximum contact, fastest chill

Flake ice is thin, dry, sub-zero shavings scraped off a chilled drum. It has an enormous surface area for its weight, so it drops product temperature faster than any other form and moulds around irregular shapes — whole fish, fillets, prawns, leafy vegetables — with total contact and no pressure points. That makes it the standard in fish processing halls, on display counters, and in pack houses where produce must be pulled down to temperature quickly and not bruised.

The cost of that performance is melt rate. Flake ice’s huge surface area cuts both ways: it chills fast and it disappears fast. It is a poor choice for a multi-day boat trip or a long unrefrigerated journey. Flake plants are also the most demanding on refrigeration and need good water quality. Use flake where product is being chilled and held under a roof with a steady ice supply, not where it has to survive a two-day trip on its own.

Matching the ice to the job

• Marine fishing, long field holding, no power — block ice, crushed at the landing centre
• Fish processing, pack house, display, rapid chilling under a roof — flake ice
• Mixed use across food service and produce, bagged sales, medium hauls — tube ice
• Long refrigerated-truck distribution — ice becomes a top-up to mechanical cooling; flake or tube for contact, block if the reefer is unreliable

Many established operations run two types — flake for the processing line, block for boats and outbound trucks — because no single form does both jobs well.

Sizing the plant

The driver is daily ice demand in tonnes, and it is bigger than people expect. You are not just cooling the catch or the harvest; you are removing the field heat it arrives with, replacing ice that melts in transit, and covering peak days that run well above the average. Under-size the plant and you are buying ice from a competitor on your busiest days. Getting this right needs your throughput in kilograms per day, the temperature the product arrives at, how far it travels and in what, and your peak-to-average ratio — so we size an ice plant to those numbers rather than to a nameplate figure.

Storage matters as much as production. Ice made overnight has to be held in an insulated ice store or bunker until the morning rush, and that store has to be big enough for a full day’s output plus a buffer. A plant with too little storage effectively produces only what it can make in real time during the peak.

Running costs and water

Ice making is electricity-intensive, and in Bangladesh that means planning for load-shedding — an ice store gives you a few hours of buffer, but a long outage without backup power means no ice when it is needed most. Water quality feeds directly into ice quality: hard or dirty water scales the machine and makes cloudy, fast-melting ice, so most plants need water treatment ahead of the ice maker. Condenser heat rejection — air-cooled versus water-cooled — affects both running cost and how the plant copes with a hot afternoon.

The right plant is the one matched to how your product actually moves after it is iced. Tell us the product, the volumes, the journey and the power situation, and we will specify block, tube or flake capacity and the ice storage to go with it.

Ice is a top-up, not the whole cold chain

Even the best ice only holds product at around melting point, and only for as long as it lasts. It does not freeze anything, and it cannot pull a warm load down and keep it there for days on its own. Treat ice as the cooling for the leg you cannot mechanically refrigerate — the fishing boat, the open truck, the market stall — and hand the product to a chiller, reefer or cold room as soon as one is available. A plan that leans on ice alone from catch to retail will lose quality on a hot day, which is the day it matters most.

Hygiene and the water behind the ice

Ice that touches fish or produce is a food-contact surface. Made from untreated water, it can carry the same bacteria as its source, and a dirty ice store or a scoop left on the floor recontaminates ice that was clean when it was made. For anything heading to export or organised retail, the ice plant needs treated potable water, a clean and enclosed ice store, and handling tools kept off the ground — the same scrutiny a buyer’s auditor applies to a chill room also lands on the ice supply feeding it.

Ice-to-product ratio and box design

For chilled transport in an unrefrigerated vehicle, the working starting point is roughly equal weight of ice to product, going higher in hot weather and on long runs. The container matters as much as the amount: an insulated tub or box needs a drain so meltwater runs off instead of pooling around the fish, and the ice should be layered above and below the product, not just piled on top, so cooling is even. Flake and small tube ice give the most contact for a fast pull-down; block ice, once crushed, lasts longest on the road. Getting the ratio and the box right is what decides whether the product arrives at market temperature or halfway warm.

Planning an ice plant for a landing centre, processing unit or pack house? DE International sources ice-making and refrigeration equipment from China and delivers it into Bangladesh with installation support. Contact us via the contact page, see the services page, or the shop. Related: cold chain for shrimp and prawn export, cold chain for hilsa, and pre-cooling fresh produce.