Cheese Vat Product

Overview

The cheese vat is where milk becomes curd. Whatever the cheese — cheddar, gouda, mozzarella — the first hours of its life follow the same sequence inside this one vessel: warm the milk, add starter culture and rennet, let it set into a gel, cut the gel into grains, cook and stir the grains, then drain the whey. A modern enclosed vat automates the entire sequence with a Process Controller recipe system and cleans itself afterwards through CIP Cleaning System, so a single operator can run several 10,000 L batches a day.

Open rectangular vats survive in artisan dairies, but industrial plants use enclosed vertical or horizontal vessels (the Dutch "Ost" and double-O designs are the common patterns) because closed vats hold temperature precisely, exclude contamination, and connect directly to clean-in-place circuits.

How it works

Milk enters the Jacketed Vat Body at 30–33 °C and the Heating Circuit circuit holds it there while culture acidifies it. Heating is deliberately indirect and gentle: plant steam never touches the milk. Instead the Modulating Steam Valve injects steam into a Hot-Water Module, and a Coolant Pump circulates that hot water through the Dimple Jacket welded to the lower shell. Because the water film is only a few degrees above the milk, proteins never burn onto the Inner Product Shell. Two Pt100 Temperature Probes — one in the milk, one in the jacket — let the controller follow cooking ramps as shallow as 0.2 °C per minute.

After renneting, the milk sets in 25–40 minutes into a uniform gel. Cutting is the step that defines the cheese: small grains drain more whey and give a harder, drier cheese; large grains keep moisture for soft varieties. The Agitator & Cutting Drive does both cutting and stirring with the same tools. Each Stir/Cut Tool Frame is a flat panel strung with tensioned Curd Cutting Wires on one face. Rotating one way, the blunt frame edge leads and the tools stir without damaging the grains; reversed, the wires lead and slice the coagulum into 3–15 mm cubes. The Tool Drive Gearmotor runs through two Helical Gear Pair reductions to turn the Tool Drive Shaft at 1–12 rpm, with an Encoder closing the speed loop — cutting starts at the slowest speed to avoid shattering grains into fines, which would be lost protein in the whey.

Cooking follows: the jacket raises the stirring curd to 36–55 °C depending on recipe, firming the grains as they expel whey. After 30–90 minutes of cook-and-stir, the Whey Drain System takes over. The Whey Strainer Screen, a wedge-wire strainer with 0.5–1 mm slots, holds the grains back while the Whey Drain Valve opens and the Whey Transfer Pump sends whey — roughly 90 % of the original milk volume — to storage for protein recovery. The Level Probe and the frame Load Cells track exactly how much has left, since whey-off volume is a recipe parameter. Curd then leaves through the flush Bottom Outlet Valve to presses or a cheddaring belt.

Hygienic design

Everything about the vat's construction follows EHEDG and 3-A hygienic rules. The Inner Product Shell is polished to Ra ≤ 0.8 µm with crevice-free welds so nothing harbors biofilm. The Hygienic Shaft Seal where the tool shaft enters is a food-grade EPDM design that survives 85 °C caustic. The Support Frame sets a permanent slope toward the outlet so the vessel drains completely, and its Adjustable Legs stand on sealed levelling feet clear of the floor for washdown.

After each batch the CIP Cleaning System system washes the closed vessel in place: a pre-rinse, 1.5–2 % caustic at 75–85 °C, an intermediate rinse, nitric acid at 60–65 °C, and a final rinse, all delivered through rotating CIP Spray Heads in the ceiling at 1.5–3 bar. CIP Supply Valves isolate the product piping from the cleaning circuit, and a Pressure Sensor verifies spray supply so a blocked head cannot pass unnoticed. The tools keep turning slowly during CIP so their shadowed surfaces get coverage.

Control and batch records

The Process Controller PLC runs the whole recipe: fill volume, ripening time, rennet dose point, set time, cut speed profile, cooking ramp, stir speeds, and whey-off volume, displayed on a touchscreen HMI. Dairies audited under food-safety schemes rely on its batch log — every temperature, time, and volume is recorded against the batch number, which matters when a 15,000 L day of milk is at stake. Interlocks tie the Hinged Manway Lid lid to the drive so the tools can never turn with the lid open.