IMPORTANCE OF USING CULTURE ACTIVITY UNITS INSTEAD OF WEIGHT
Understanding the Importance of Accurate Culture Dosing
In yoghurt production, the correct dosing of starter cultures is critical to ensuring product quality, consistency, and shelf-life. While it may be common practice to measure starter cultures like LYOFAST Y 438 A in grams, this approach is technically flawed and can lead to significant inconsistencies in the final product. This is due to the fact that the weight of the culture packet does not reliably reflect its activity level, especially when considering batch-to-batch variability during manufacturing.
Why Weight is not a Reliable Measure
Starter cultures like LYOFAST Y 438 A are standardised based on activity of unit, not weight. The weight of a culture can vary significantly due to differences in the growth medium used during production.
Two different batches of the same culture (100 UC packets) were found to have vastly different weights:
* Batch A: 230 grams
* Batch B: 155 grams
If dosing is based on weight rather than activity, this could result in significant overdosing or under-dosing - both of which have consequences for product quality ad consistency.
Recommended Best Practice
To ensure consistent fermentation and final product quality, always dose according to culture activity (UC), not weight.
General Dosage Guide:
* 5 UC per 500 L Milk
* 10 UC per 1000 L Milk
Upon receipt of new culture batches, weight the entire packet and then calculate the amount to be used based on the number of UC. If necessary, divide the packet into smaller, sterile containers for precise dosing.
Risk of Overdosing
While it's always preferable to slightly overdose rather than under-dose when unsure, consistent overdosing can still have negative impacts, including:
* Increased production cost
* Post-acidification, leading to:
* Uncontrolled or overly rapid fermentation,
* Shorten shelf-life
* Yoghurt that becomes too sour before its expiry date
* Texture issues, such as:
* Grainy or lumpy yoghurt,
* Excessive thickness or premature gelling,
* Whey separation due to protein denaturation
Risk of Under-Dosing
Under-dosing is generally more detrimental and should be avoided. Key issues include:
* Slow/Incomplete fermentation - too few bacteria - long process time & high final pH,
* Weak gel - delayed protein coagulation - runny, unstable yoghurt,
* Increased risk of spoilage or contamination - starter can't dominate microbes - off-flavours & safety concerns,
* Poor flavour - insufficient metabolic activity - bland taste,
* Shorter shelf-life - inadequate preservation by acidity - early spoilage,
* Process inefficiency - extended incubation - lower productivity & higher costs.
Conclusion
To maintain consistent yoghurt quality, proper fermentation control, and product shelf-life, always calculate and dose starter cultures based on the activity (UC), not on their weight. This approach ensures optimal performance of the culture and a reliable, high-quality end product.
If there's ever uncertainty regarding the activity in a batch, erring slightly on the side of overdosing is safer than risking under-dosing - but best practice remains accurate dosing based on activity.
Attached:
- Dividing a 50 UC culture into 25 x 200 L Batches
Technical Support:
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