An Italian cooperative producing DOP (Designated Origin of Production) hard, Grana-style cheese has invested in a fully automated Microflow XL-Brine micro-filtration system from Pall Corporation in order to optimise the quality of the brine at its various plants and reduce its overall costs for waste stream disposal.
Owned by 30 small producers, the cooperative was looking for a user-friendly, simple technology to be installed in a truck for regular operation at each of its cheese plants.
The Microflow XL-Brine systems from Pall are specifically designed to meet the needs of brine purification in modern cheese plants, and clarification is achieved without the need for filter aids or centrifuges.
Salting by immersion in brine is a process used for many varieties of cheese worldwide. During repeated immersions fat, curd particles and microorganisms from the cheese, plus the accumulation of proteins and other components, builds up a nutrient-rich environment for salt-resistant microorganisms. Reused brine can become a reservoir for unwanted microorganisms such as gas- or pigment-producing bacteria, yeast and mould, or salt-resistant pathogens that can cross-contaminate the cheese and impact quality.
At the cheese operation in Northern Italy, brine had a typical turbidity of >100 NTU. Micro-filtration, at regular intervals of 3-6 months depending on the dairy, was selected to reduce the cheese cross-contamination risk and to provide high brine clarity.
With the high local disposal fee for salty effluent, brine micro-filtration was expected to bring significant benefits to the cooperative where the brine salting process is carried out in 20 days on average, in pools ranging from 20 to 200m3, and with a throughput of 2m3 per hour.
Other important requirements made of the Microflow solution at the Italian cooperative included the ability to handle high contaminant load and variation from batch to batch, optimised water and chemical consumption during cleaning cycles, and user-friendly operation with reduced labour and downtime.
XL-Brine Microfiltration System was selected for the constant and high filtrate brine quality it provides, and because it offers a reliable, environmentally friendly solution for extending the life of brine and preventing cheese quality downgrades.
The typical performance of the Microflow system is a filtrate turbidity below 0.8 NTU, combined with high microbial reduction efficiency, typically up to a log reduction value (LRV) >5 in operation in the cheese plant, and up to LRV >10 when challenge tested with Listeria by an external laboratory.
The Pall Microflow system consists of Polyvinylidene Fluoride (PVDF) hollow fibres designed with a high mechanical strength and excellent chemical resistance. It is capable of achieving high flux rates within a compact footprint.
When operated with an optimised combination of hot water and chemical cleaning sequences, reductions of up to 50% in water usage and 30% in cleaning time and chemicals have been demonstrated, compared to other membrane systems.
Additional equipment, including a hot water production unit, a chiller and a coarse bag filter to remove large particles and fines, completed the installation on the truck, which provided efficient and autonomous operation at each cheese processing plant.
The Microflow XL-Brine technology platform addressed the need for reliable and cost-effective brine regeneration and eliminated the use of traditional solutions such as DE pre-coat filters or heat exchangers.
According to Pall, the Microflow XL-brine system’s larger diameter high flow modules with 21.5m2 of filter area have at least twice the filter area of typical competitive hollow fibre modules.
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