I experienced nothing short of a paradigm shock recently, when a client warned me prior to the audit of their facility, saying “we clean using water every 3 months”. My reaction was based on historical thinking on low moisture foodstuffs and the hazard of pathogenic microorganisms and it required a massive rethink in preparation for this audit. Read what the experts say…
Are low-moisture items safe from contamination?
I think many of us had this opinion: Most food manufacturers of low-moisture items should not find bacteriological issues to be an issue, as the water activity present in these foods was not conducive for microbiological growth. However recent wide-spread foodborne disease outbreaks would prompt us to think differently. These outbreaks include products such as:
- Peanut butter and peanut butter paste (Aw 0.70)
- Cookie dough (Aw 0.80)
- Pistachios (Aw 0.72)
- Milk chocolate, (Aw 0.65)
- Hydrolyzed vegetable protein (Aw 0.60
The culprits of these outbreaks are led primarily by Salmonella species, as well as E. coli, but are not limited in scope to these two organisms. So the scientists have been busy and there is ample guidance that we should take very seriously.
Codex and Low-Moisture Foods
The first of these documents is the Code of hygienic practice for low-moisture foods CAC/RCP 75-2015 published by Codex Alimentarius. This Code covers GMPs/GHPs for the manufacturing of low-moisture foods for human consumption. Check out the list of products that should take heed:
- dried fruits and vegetables (e.g. desiccated coconut)
- cereal-based products (e.g. breakfast cereals)
- peanut and other nut butters
- dry protein products (e.g. dried dairy products and soy protein)
- confectionary (e.g. chocolate and cocoa)
- snacks (e.g. spice-seasoned chips/crisps)
- tree nuts
- seeds for consumption (e.g. sesame seeds and sesame seed paste)
- spices and dried aromatic herbs
- specialized lipid based nutritional products for the treatment of moderate and severely acute malnutrition
- Milled grain products such as flour may be within the scope when used in foods that would not be subject to a microbial inactivation step.
The publication highlights that although the water activity (aw) of low-moisture foods is often well below 0.85 and foodborne pathogens such as Salmonella cannot multiply under these conditions, the cells can remain viable for extended periods of time. For Salmonella spp., the infectious dose is thought to be very low, as demonstrated by the small numbers of cells per serving recovered from low-moisture foods implicated in outbreaks.
Controlling the nasties
According to Codex, pathogens such as Salmonella can be difficult to control in a low-moisture food operation environment, because they can persist for prolonged periods of time in the dry state and in low-moisture products. Investigations from Salmonella outbreaks indicate that the safety of low-moisture foods depends fundamentally on the control of Salmonella in the food operation environment.
It seems that effective PRP’s such as maintaining good hygienic practices, hygienic design of equipment, proactive maintenance programmes, control of incoming materials, and effective ingredient control in the low-moisture food establishment, will help prevent the contamination of low-moisture foods with pathogens.
High risk in dry product handling
Seems ridiculous, but it’s not. Special attention should be paid to products:
- That are exposed to the processing environment following a pathogen reduction step
- That are not subjected to a pathogen reduction step
- For which ingredients are added after a pathogen reduction step
This means is that is it possible to have a high risk area in a facility handling low water activity products. The key is keeping water out and using dry methods of cleaning.
Find out more…
If you would like to study more on this fascinating topic, read some of these:
CAC RCP 75 Link
Persistence and Survival of Pathogens in Dry Foods and Dry Food Processing Environments
