UNDERSTANDING WATER CONTAMINATION VS LOW MILK SOLIDS

UNDERSTANDING WATER CONTAMINATION VS LOW MILK SOLIDS

When milk appears diluted, thin, or performs poorly during processing, the root cause generally falls into one of two categories:
1. Water contamination in the milk, or
2. Milk with lower-than-expected natural solids.
Correctly identifying which of these is occuring is critical, as the cause, risk, and corrective actions differ significantly.

WATER CONTAMINATION IN MILK
If water is present in the milk, this is not a natural occurrence and must be treated as a serious quality and integrity issue.
Water contamination may occur due to:
* Undetecged water leaks within the processing system,
* Deliberate dilution (milk theft followed by replacement with water to maintain volume),
* Equipment-related failures, especially during heat treatment.

One of the most discreet and often overlooked sources of water ingress is the Plate Heat Exchange (PHE). Cracks in PHE plastes can allow water to leak into milk, particularly during certain generation phases, without being visually obvious.
Because these leaks are often small, they may:
* Go unnoticed for extended periods,
* Gradually dilute milk solids,
* Negatively affect fermentation, yield, and final product consistency.

Water-contaminated milk results in:
* Lower total solids,
* Poor yoghurt and Maas body,
* Reduced cheese yield,
* Inconsistent fermentation behaviour.

NATURALLY LOW MILK SOLIDS
Milk with low solids can appear diluted, but this is not due to added water. Instead, it is often linked to cow nutrition and seasonal changes.
During the rainy season, when cows consume large amounts of lush green feed, the following can occur:
* Milk volume increases,
* Milk solids (fat & protein) decrease.
This is a well-known and natural phenomenon in dairy production. If cows are feeding primarily on green pasture without sufficient solid feed supplementation, milk solids may drop noticeably.

Importantly:
* Green feed alone does not add solids to milk,
* Supplementary feeds such as maize, corn, or other energy-rich solids are required to increase milk solids,
* One would not expect solids in feed to reduce milk solids - the opposite is true.

Low-solids milk will affect:
* Fermented product thickness,
* Cheese yield,
* Overall product performance, even though no water has been added.

KEY DIFFERENCES AT A GLANCE

ISSUE

WATER CONTAMINATION

LOW MILK SOLIDS

Cause

Equipment leak or dilution

Nutrition & season

Nature

Abnormal & unacceptable

Natural & expected

Risk

Food safety & integrity

Quality & yield

Action

Immediate investigation

Feed & formulation adjustment






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