Controlling Botulinum

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Controlling botulinum is a vital element of food safety that can have dire consequences if ignored.

February 24, 2022

What is Botulinum?

Botulinum, or Clostridium Botulinum, is a species of the Clostridium. This bacterium can produce toxins in low-oxygen conditions that are deadly. Low oxygen foods include, vacuum packed, canned, and foods with high oil content.

Unlike many other pathogens, labs do not routinely test for C botulinum for two reasons;

It is so deadly that testing a representative sample of food does not provide enough assurance that the entire batch is free from the pathogen.

Most labs do not have the containment levels required to propagate such a deadly bacterium.

Clostridium – Photo by CDC on Unsplash

How it is controlled

So, if routine micro testing isn’t the answer what is?

There are a few ways you can control C botulinum:

  • freezing the food, which works by inhibiting botulism rather than destroying it. This means that once the food is thawed, the botulinum can begin to take effect again, so short shelf-lives of < 10 days are required post thawing
  • high heat / temperature combinations, e.g. like those used in canning
  • having a short-shelf-life of < 10 days for product stored at temperatures > 3°C
  • maintaining a low moisture content or pH throughout the food

Testing

At Express Micro Science we can test your product to prove that C botulinum cannot grow under chilled conditions, so that longer shelf-lives can be achieved.

  • pH – food must be 5 or less throughout the food or throughout all components of complex foods
  • Aqueous salt – food must have 3.5% or greater of salt in the aqueous phase throughout the food or components of complex food
  • Water activity (aw) – food must have 0.97 aw or less throughout the food and throughout all components of complex foods

If your product meets any of the above requirements you are safe to extend your product’s shelf-life beyond 10 days.

A Bug’s Life: Staphylococcus Aureus

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Staphylococcus is a common bacteria that has many strains which can cause skin infections, food poisoning and even Toxic Shock Syndrome.

February 17, 2022

Staphylococcus, or Staph., is a type of bacteria most often found in the upper respiratory tract as well as on our skin. Most people will have some of these bacteria on their bodies – which allows for the mildly amusing anecdote that staph is found – on the Staff! It is a common skin infection and can be present in abscesses, and sinus infections (like sinusitis). There are different strains of Staph. including Staphylococcus aureus and Staphylococcus epidermidis.

At EMS, we test for Staphylococcus aureus, which can cause food poisoning by developing toxins in food and when ingested causes food poisoning. Symptoms develop within 1-6 hours and last anywhere from 30 minutes to 3 days. Food poisoning caused by Staphylococcus aureus is one of the quicker routes to a sore stomach.

Outbreaks of food poisoning caused by Staphylococcus aureus are rare, especially documented cases, due to the quick onset and recovery of victims. However, any outbreak is usually associated with products that are subject to handling during preparation or dairy products which can become contaminated from the udders of cows and sheep.

How can you prevent spreading Staph.? Wash your hands thoroughly with soap and water, especially before preparing food. If you are ill, avoid preparing food, and cover any open wounds on the hands or wrists with gloves.


The Micro Profile:

Name: Staphylococcus Aureus

Family: Staphylococcaceae

Type of ‘Bug’: Bacteria

Appearance under a microscope: grape-like clusters with round, golden-yellow colonies


History

First discovered in 1880 by Scottish scientist, Alexander Ogston, while performing a procedure. He described the bacteria as looking like “bunches of grapes”. Later, in 1884, Friedrich Julius Rosenbach found that he could differentiate the bacteria by the colour of their colonies: Staph. Aureus was named because of it’s golden colouring.


How do EMS test for Staphylococcus?

The method we use the most to test for Staph, which we are UKAS accredited to carry out is Method No 16 based on BS EN ISO:6888: Part 1: 1999 using Staphytec plus latex confirmation. If you want more information on this method, you can find it here.

EMS Taste and Test – Chilli

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The sensory and nutritional results are in and they might surprise you…

June 2, 2021

Our second Taste & Test was Transport Manager Alan’s Chilli and the sensory results were encouraging!

Here are some highlights:

The Nutritional results were, however, a little surprising and show why nutritional analysis can be so important.

The chilli was prepared with the view that it would be a main meal portion (albeit an indulgent one). We’re all guilty of piling our plates a little high when it comes to our favourite comfort foods, however the nutritional results came back with one mission: to shame us into sharing portions!

In all seriousness, even if this dish was sold as a starter for 2, it would still be very unhealthy. Tasty, comforting and everything you might want after a tough week, but is it worth it?

In the chilli’s defence there are ways to make it healthier, swap out the cheese and nachos for boiled rice, maybe a quarter an avocado instead of half. Also, unsure what % fat that Alan used but you can get less than 5% lean steak mince. This would all help in making a tasty dish a little less likely to kill us all!

The above would all be ways of making this recipe healthier for at home consumption. However, calories may not be as concerning when dining out for a special meal as you would not be eating this indulgently every day.

It is still valuable to customers to be aware of the contents of their food, if someone has high blood pressure, it would be important for them to try to avoid food high in salt. For most people though the odd cheeky high fat/salt meal would not be the worst thing in the world but with the calories on display they can make an informed choice and decide for themselves if this were what they would like to eat. This chilli was worth the calories. 

In the restaurant industry, food portions would have been determined by price of ingredients, staff wages, electricity, rent of property etc. In many eateries, certain dishes can be ordered as a main portion or a starter. This is an option that has been displayed here, with the chilli initially being designed as a main but has been finally presented as a sharing starter for two. Halving the calories per portion but not skimping on taste!

Food additives: Sulphur dioxide

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Nowadays, the use of SO2 and sulphites comprises a wide array of food and drinks…

May 25, 2021

By Fran Navarro Fuentes

Food additives, according to the WHO, are “substances that are added to food to maintain or improve the safety, freshness, taste, texture or appearance of food”. Additives can be natural, i.e. derived from plants, animals or minerals, or synthetic. Either way, its use cannot mislead consumers and must have a technological function. For instance, salt (in meats), sugar (in marmalade) or sulphur dioxide (in wine) have been used for centuries with the main purpose of preserving food.

The international organism responsible for the safety of consumers regarding food additives is the joint FAO/WHO Expert Committee on Food Additives (JECFA). Only after a risk assessment is performed and it doesn’t represent a risk to health, a food additive can be used at specified levels for specific foods.

Focusing on sulphur dioxide (SO2) and sulphites, known in the food industry as E220-E228, these are used as preservatives due to their antimicrobial properties avoiding spoilage caused by microorganisms, and antioxidant properties inhibiting chemical and enzymatic oxidation, thus preventing food from darkening [1].

How did SO2 become an additive that was used in the wine industry? Well, back in the 8th century BC, houses and even ships were fumigated for vermin with sulfur power. Soon it was also noticed that the fresh fruits and flowers that were in the fumigated room lasted longer. In the wine industry, pitch was used to fill cracks in amphorae containing the wine. However, when used inside the clay jar, it didn’t fit the purpose as it was found to be soluble in alcohol. Despite this unfortunate inconvenient, its preservative qualities were quickly perceived preventing wine spoilage due to bacteria or yeast growth.

Nowadays, the use of SO2 and sulphites comprises a wide array of food and drinks such as snacks, biscuits, fruit juice, syrup, wine, cider and beer as well as fresh or dried vegetables and fruits, jam and marmalade, nuts, seafood and crustaceans and meat.

However, even though SO2 and sulphites are widely used due to its efficiency as food preservatives, they can cause dermatitis, urticaria, hypotension, abdominal pain and diarrhea to sensitive people and could represent a risk for asthma patients [2]. Therefore, maximum allowed concentrations are imposed by legislation and vary depending on the product [3].

References:

[1] The use of Sulphur Dioxide http://www.uwe-hofmann.org/The%20use%20of%20Sulphur%20Dioxide.pdf Last visited 4/4/21

[2] Vally H, Misso NL. “Adverse reactions to the sulphite additives.” Gastroenterology and hepatology from bed to bench vol. 5,1 (2012): 16-23.

[3] List of permitted preservative for each specified food and the proportion permitted: https://www.legislation.gov.uk/uksi/1989/533/made Last visited 4/4/21

EMS Taste & Test – Buffalo Wings Nutritional Results

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The Nutritional Results for our Buffalo Wings

May 21, 2021

The results are in!

Our very first EMS Taste & Test was a hit – and we’ve already had our second (but more on that to follow shortly)! The sensory test for the Buffalo Wings was a great place to start; it gives the food provider (in this case, the MDs husband, Stuart) a better idea of a flavour profile, appearance feedback and an approximate price that tasters are willing to pay for the dish. All of this information can used to help product placement and provide verified information to customers on flavour and the tasting experience. We currently offer reports of this nature to major retailers such as Lidl, who use our reports to ensure products sold in their stores are as the producer intended and meet all mandatory labelling requirements.

Our Taste & Test would not be complete without a full run-down of the nutritional content. On the front of food products, you buy in a supermarket, you will see a ‘traffic light’ breakdown of nutritional information. This is a legal requirement.

Our Buffalo Wing results are below:

Buffalo wings may not be the healthiest option on the menu and if you are trying to limit your calorie intake or avoid saturated fats or salt, maybe keep them as a special treat! However, they are very high in protein and low in sugar, so if you’re looking to bulk up a bit, hit the gym and want a bite full of protein, these maybe the ideal post work out snack!

Fun fact! Why are Buffalo Wings called buffalo wings when there is no buffalo meat to be found?

It is generally agreed by historians that Buffalo wings were invented by an eating establishment called Anchor Bar in Buffalo NY USA —or rather, their owner Teressa Bellissimo did — the rest of the origin varies but a popular story is after being accidentally shipped wings instead of other chicken parts and, as such, the now famous snack was invented out of a desire not to waste perfectly good poultry. (ref: https://www.tasteofhome.com ; https://en.wikipedia.org/wiki/Buffalo_wing)

If you’re interested in having a go at making these sumptuous buffalo wings at home, click here, put ‘Buffalo Wings’ in the subject line and we will send you the recipe!

First Ever EMS Taste & Test

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We have launched EMS Taste & Test, a place to share your favourite foods and get the the nutritional information back for it. Curious about the nutritional value of your family favourite recipe? Make a batch and send it in!

May 4, 2021

We have launched a new programme of Taste and Test for all those adventurous chefs and retailers out there who want feedback on their favourite dishes! We’re starting small by offering first to our employees and soon after hope to get the local community of cafes, delis and restaurants involved – what happens after that? Well, we hope it will become a new phenomenon where people can access free information on nutritional values, recipes, and recommendations of food in their own locals.

Our first meal was made by our Managing Director’s husband, Stuart, who is a fanatic for American style Buffalo wings. As they are not readily available in the UK he has scoured the internet for the best recipe to make at home. Our MD, Jennifer, gets to enjoy this dish frequently at home and thought sharing this American favourite dish to those who may never of even heard of it was a great launch for wonderful unknown taste sensations to come.

Jennifer, with Stuart’s help, prepared enough buffalo wings for everyone with EMS to have a taster portion as well as a serving for chemistry to test for nutritional content. All the tasters were asked to complete a short survey scoring the dish on appearance and taste. They were also asked to describe the dish to someone who had never eaten it and say what they would be prepared to pay for the meal in a pub.

The sensory results are in are summarised here:

The nutritional report will be ready next week, and we will show you the completed report then. If you are interested in participating in our new venture, please get in touch there is no cost to you but providing the food.

Happy eating!

The microbiology behind the bread

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The science in your sourdough!

April 20, 2021

By Antonio Baena Marin

As many others, this lockdown has made me my found new hobbies to do at home, so I decided to take my father in law’s advice, and I started to make my own Sourdough Bread with little hope on the result. I was shocked when I realised how the process of making bread is so similar to my job, but instead of working in the lab it takes place in the kitchen bench.

The first thing I had to do was growing my own Sourdough Starter. That took around 5 days and for that I only needed to add an equal ratio of wholemeal flour and water (Yes! As simple as that). Whole grain flour contains Wild Yeast and Lactobacilli which are the organisms needed in the fermentation of the bread. All you are looking for is to create a nice community of wild yeast and Lactobacilli that will create a symbiosis between them.

Once the starter is ready and active (Figure 1), we can start preparing our bread which is basically a mixture of sourdough started, water, salt and flour. Once the dough is mixed and kneaded, you just have to leave it and the microorganism will work their magic (also known as fermentation in the lab). That can take from 2 to 6 hours depending on the temperature of the room.

Figure 1. Sourdough Starter. Inactive Starter in the left and Active Starter in the right (red line marks the level at the start).

As microbiologist, we know that the optimum temperature for yeast to grow is 25oC, so we are aiming for that temperature. This is very difficult to achieve in cold countries like Scotland, especially in winter, but you can always place your dough in a sunny spot, next to the heater or inside your oven/microwave with the lights on (this could be considered our small incubator, like the ones we have in the lab). During this process, the dough should have risen by 30-50% (Figure 2). All is happening inside the bread is two different kinds of fermentation: Wild yeast will perform an alcoholic fermentation using the sugars; yeast will produce ethanol that will be mostly evaporated while baking the bread and CO2 that will be trapped on the gluten structure creating those nice and characteristic holes in the baked bread and causing the dough to rise. Lactobacilli digest the sugars and produce lactic acid that will lower the pH of and give that nice sour flavour to the bread.

Figure 2. Comparison of two bread doughs. Non-well fermented dough on top of image (not much rise after the mixture of ingredients) and properly fermented dough at the bottom of image (around 50% rise after mixture of ingredients).

Once the bread has doubled size, it is shaped and placed into the fridge for up to 20 hours in order to continue the process with a slow fermentation (by lowing the temperature the microorganisms will reduce their activity making the process much slower than when it takes place at around 25 oC) that is going to improve the benefits of our bread. It has been proven that slow fermentations help to preserve the bread (the low pH of the bread prevent the growth of other non-desirable microorganism and mould) avoiding the addition of additives to the bread. It also helps to reduce the gluten content since the gluten proteins are degraded, making the bread easier to digest compared to the commercial bread, where only a quick alcoholic fermentation takes place, enough for the dough to rise but without the other benefits explained above. It is also known that Lactic acid decreases the content of phytate, which inhibits iron and zinc absorption, increasing the nutritional benefits of our homemade bread.

What it is left to do is baking the bread and enjoy it.

Why are dilutions important?

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Check out another time lapse video explaining why dilutions are so important.

April 6, 2021

By Michael Beavitt

Accurate dilutions are one of the best used tools in microbiology for determining the number of microbes in something. No matter how many bacteria are in your initial sample, you can always dilute it down to a countable level.

In the timelapse video shown, a high concentration of E.coli was suspended in agar on the top left plate. From left to right, each plate contains a 1 in 10 dilution of that high concentration solution, then a 1 in 10 dilution of that, and so on and so forth.

Footage by Michael Beavitt

Plate one (top left) could be an example of a food sample tested in our lab with a very high bacterial load. After taking 10g of food and homogenising it with diluent, in the case of food tests, one millilitre of this solution would be added to agar, and incubated.

Each blue-green dot you see in the agar is representative of a single bacterium, which has grown into a colony. At a dilution of 1/10, there are far too many bacteria to be counted. They form a confluent lawn of growth across the entire medium. 1/100, and there’s still far too many.

The sample needs to be diluted all the way down to 1/1000000 from the original 10g suspension to allow countable colonies. Then, all it takes is some quick arithmetic to work out how many were in the 10g of food! The bottom right plate, at a dilution of 1/1000000, had 44 colonies. This means that 44000000 bacteria were present in 10g of food.

It’s very rare that anything will have this much E.coli growing on it – it was just used as an example in this case, because it’s easy to grow, and brightly coloured on the agar used. Ordinarily only a 1/10 dilution will suffice for food products! The same principles apply for other enumerations, however – an aerobic colony count will often require 1/1000 or 1/10000 for raw meat and other high risk food types.

If you’re interested, the video was shot for 24 hours, and the E.coli was incubated at 37ºC on TBX agar. Normally they’re incubated at 41.5ºC, but unfortunately my camera is not rated for those kinds of temperatures! The reason that the top 3 plates begin to crack and shrink is because all the lids were left off for ease of filming, allowing the water in the jelly to evaporate. The prolific bacterial growth also sped up the process.

Sampling and Sampling Plan

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A guide to sampling and sampling plans

March 30, 2021

By Michelle Milne

When designing a sampling and analysis plan it is vital that producers identify the information they expect to gain from the plan. For example, to produce a compliant nutritional label that represents the average nutritional data of the whole population of the product on sale. The plan must give an average value to be used on the label taking into account the variability of the product. Robust average nutritional data will help the producer defend a challenge to the label. For example if an independent sample of fish tested by trading standards indicates a 20% variance between the label fat value and the reported result. Evidence of a 25% variance in fat levels over the year would adequately explain the anomaly.

The adequacy and condition of the sample or specimen received for examination are of primary importance. If samples are improperly collected and mishandled or are not representative of the sampled lot, the laboratory results will be meaningless. When submitting a sample for analysis the producer is submitting a small sample of the total population as an estimate of the average of the whole population. In the same way that no two humans have the same fat, protein and moisture ratios the same applies to fish, sheep, pigs or cows etc. A large number of factors can affect the nutritional values of a product. Below is a list of just some factors.

Ingredients:

  • Seasonal Variability
  • Source Variability
  • Supplier Variability
  • Batch Variability
  • Homogeneity

Production:

  • Ingredient Weight Variability
  • Portion Weight Variability
  • Cooking Variability
  • Line Variability
  • Batch Variability
  • Homogeneity
  • Sampling Variability

Testing:

  • Sample Preparation Homogeneity
  • Analytical Uncertainty

Know your product, decide which of the above factors most affect your product and tailor sampling plan to match, compare results from batch to batch or the start, middle and end of a run. From these multiple tests build a picture of the variance in nutritional components such as fat, protein and salt so that all factors influencing the inherent variance of your product are incorporated into a robust nutritional label. Thus providing consumers with the most accurate information about your product.

Fanny ‘Lina’ Hesse: One of microbiology’s first forgotten pioneers

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The woman behind the agar in your plates.

March 23, 2021

Ever used agar? (Of course you have!) You’ve Fanny Hesse to thank for that. She was born in 1850, though little is known about her early life, and she married her husband, Walther Hesse, in 1874. Walther was a keen country doctor with a passion for hygiene and public health. But, in 1881, he went to study in the Berlin laboratories of Robert Koch, the ‘father of bacteriology’ himself. Fanny, while running the household, cooking the meals and educating their sons, worked alongside her husband as an unpaid technician. She cleaned the equipment and prepared bacterial growth media, which was typically beef broth.

At this time, gelatine was the key ingredient used to solidify the media, but it would melt at 37 degrees C, making this an unreliable base for the bacteria to grow on. Additionally, some bacteria would liquify the gelatin, which was a pitfall for Koch, Walther and their experiments.

Fanny was a keen cook, and was aware of the downfalls of gelatin, through making puddings and jellies at home. While living in America, a neighbour had introduced her to the gelling agent, agar, and its ability to maintain its gel state at warmer temperatures. After suggesting the substitution of gelatin for agar to her husband Walther, Koch began to use agar in his experiments to cultivate the bacteria that cause tuberculosis.

In 1882, Koch published a paper on tuberculosis bacilli. In the paper, Koch mentioned his switch to agar from gelatin, without any reason for the substitution, and did not credit Fanny or Walther for their discovery. The use of agar instead of gelatin was a huge step forward for microbiology, as without it, scientists would not have been able to grow microbes at higher temperatures, which would have resulted in a huge gap in our knowledge of bacteria and its behaviour.

Though the Hesse’s were overlooked at the time for their contribution to science, there is, fortunately, plenty of information about Fanny and Walther online – Fanny even has her own Wikipedia page. In recent years, she has been dubbed the ‘mother of microbiology’ for her breakthrough, without which microbiology would be at a loss. So, next time you reach for the agar, send some gratitude to Fanny Hesse, and remember that many great scientific discoveries had even greater women behind them.