So food safety for meat alternatives might not seem the most jazzy title but if you want a reasonable shelf-life and no upset stomachs then it pays to get your formulations right.
Meat has long been prone to microbial spoilage and lots of developers have sought ways to counter this issue. Fear of Clostridium and Campylobacter is enough to threaten the consumer but there are many microorganisms which quite happily alter the flavour profile of food that also damage a food’s reputation.
The Factors That Impact Shelf-Life
In a general sense, this section is an overview of more wide-ranging factors that affect all foods and not just meat alternatives. You still need to think about them however when designing a food and employing the hurdles that will make it safe and keep it safe. The key enabler as a food developer is keeping an eye on the HACCP plan and how this will be structured. Keeping food safe is integral to this so the HACCP process needs to be borne in mind. That also implies that quality assurance, analytical and sensory testing methods must be developed too, simply to avoid costly mistakes later on.
-The Intrinsic Factors
There are the intrinsic factors which are those relating to the food itself. The quality of the raw materials is a key point and making sure the initial microbial load is as low as possible is vital. Unless the starting material has to be fermented, there is no benefit in starting with a high microbial load because it must be dealt with later on.
Product composition can be a feature. Is your new food homogeneous or heterogenous? That means does it have a simple, single component or is made up of many types of ingredients or layers which contribute different textures and levels of aeration.
The formulation of the food has always been one of your best weapons. Making sure the moisture content (aw) is low enough really helps and a pH value which is also as low as feasible without compromising flavour etc. In the case of pH, certain acids like citric and malic could be tried. Sometimes it’s not possible to manipulate these but it certainly helps to exploit these types of hurdles.
Another way of creating hurdles is to add ingredients such as preservatives. The obvious ones such as sodium benzoate and potassium sorbate will certainly do the job but you might want a preservative free claim. Finally, how you mange oxygen availability and for that matter, managing your redox potential for the product will have a bearing.
-The Extrinsic Factors
The extrinsic factors are mainly about the way your new meat alternative will be processed. In most cases a heat treatment is still the standard approach but there are implications. The degree and rate of cooling has a bearing. Most meat-free alternatives are extruded and we’ve discussed this elsewhere but the applied mechanical forces change texture significantly.
We wont dwell on this too much but other extrinsic factors concern the type of packaging and perhaps most importantly how the food will be stored, how it will be distributed throughout the supply chain and how the consumer stores that food. Not all consumers have refrigerators for example!
Met, the real version is relatively safe as a food. That seems counterintuitive when compared to the types of protein used in meat alternative products but it seems that analysis of these products shows that they have a similar water activity and a slightly more alkaline pH than meat. This combination actually makes such products on average more risky although beefburgers have their fair share of issues. I’d be interested to know which is more of an issue.
What Are The Risky Ingredients?
When you read the news articles on food poisoning outbreaks where microorganisms have been concerned than a few culprits regularly turn up. These have all been implicated in outbreaks and are common enough in meat substitute products.
- fresh fruit
- dairy foods and ingredients
- tofu and other soy fermented foods
- bean sprouts
- rice (Bacillus subtilis especially)
Organic Acids Impact Meat Alternatives
We know of three bacteria which are problematic with meat alternatives/substitutes.
- Lactobacillus may be ideal for yogurt production or sauerkraut but they also produce lots of organic acids and even gas which is responsible for blown packaging. If their population levels are too high then an unsightly white purge can be seen inside the pack. There are some species which also produce ‘greening’ and that is down to the formation of hydrogen peroxide. The greening is in part from the colour of the manganese in the active sites of the peroxide forming enzymes as well as from changes to pigments which are usually bleached by free radical attack.
- Leuconostoc species are not pretty. In fact they produce slime which is often transparent but becomes obvious when the product is removed from its packaging. Most of these species are classed as heterofermentative meaning they produce both gas and acid.
- Listeria monocytogenes is the bacteria which produces listeriosis and its fatal for some. It needs to be considered because it is a psychrophile meaning it grows at cold temperatures such as the refrigerator. In Europe in 2015, the bacteria caused 270 deaths and upset 2,200 people so it is not to be underestimated.
The value of organic acids is that they can be used to control these spoilage and pathogenic bacteria. Lactic acid which is produced by Lactobacillus is in its own right an ingredient for controlling spoilage microorganisms because it can reduce the pH. It also controls Listeria. You can also use acetic acid which is just as effective at lower doses but contributes to the flavour profile and that might be more difficult to countenance. Take a look at what Corbion have to offer in the way of organic acid additives.
We mentioned water activity earlier. Reducing the level reduces the growth of all spoilage microorganisms. In its own right it is not going to be sufficient but combined with the use of organic acids might be good enough to severely curtail spoilage bacterial growth.
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