Food Science Basics in 6 weeks – part 6: Packaging & Technology

Can’t believe this is the last week of this first course on already. It’s been all about teaching you the basics of food science to help you in your food blogging, chef, high school, food industry or whichever other career you’re aiming for or working in!

This last week will focus on looking back at what we’ve learned, combining some of the things we’ve come across as well as having a slight look ahead into applying the knowledge by having a quick look at some packaging and technology principles.

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Re-cap – Food Chemistry

In the past few weeks we’ve looked into the basics of food science following along three different routes: food chemistry, food physics and food microbiology. I’ve chosen this approach since it can help  you link science classes and topics more easily to the different phenomena in food that we see.

In food chemistry we’ve looked at molecules and atoms. We’ve discussed how atoms are the building blocks of molecules. We then discussed the most important groups of molecules in food: the carbohydrates, fats and proteins. These are groups with a very distinct build, they can be identified pretty easily.

Proteins, two types of bonds occuring: disulfide & hydrogen bonding.

Once we defined the basic molecules we discussed how these molecules can react with one another in chemical reactions. Here is where it starts getting interesting in food. We discussed some of the chemical reactions that can take place. For instance we discussed browning reactions such as the Maillard reaction during which brown molecules are formed. We also looked into acid/base reactions and how these can go back and forth.

Re-cap – Food Physics

We then switched to food physics. In food physics we focussed on discussing several general principles to help us understand a lot of other phenomenon. We discussed water activity, how this is a measure for the amount of available water. Water activity influences a lot of food related processes around us: spoilage, growth of bacteria, chemical reactions, etc.

We also looked into the different phases: gas, liquid and solids. This comes to play in just about all cooking or food preparation. Baking a cake involves a transformation from liquid to gas whereas making ice cream involves a transformation from liquid to solid.

Last but not least we had a look at gels, emulsions and foams by looking into the science of meringues and chocolate mousse.

Re-cap – Food Microbiology

The last topic we zoomed in on was food microbiology. We didn’t zoom in on the details, microbiology is a very broad field, but focussed on the topline. We discussed the different types of microorganisms in food and looked into the bad (pathogenic) microorganisms and those that we actually need for making our foods (e.g. yeast in bread and beer)!

There is a whole lot more to be explored in the field of food microbiology, such as the influence of a microorganisms surroundings on its growth and food safety concerns in food processing. However, we’ll leave that for a later point in time.

Applying what we learned

In this last week we will combine and apply the knowledge we’ve learned in the past few weeks. We will do this by discussing a few new examples that show how to apply what we’ve learned. We’ll be using other blog posts from this blog, as well as several new examples and ideas. To cover both industrial and home-cooking students, we’ll be looking into the following three topics:

  • Pesto Food Packaging: for those of you working in food industry, one of the great ways to apply food science is in the field of food packaging. Packaging a food in a safe way and such that it remains tasty and of high quality is a great challenge.
  • Pancakes & Food Safety: in food industry food safety is top priority. It is a great chance to apply your food microbiology knowledge
  • Eggs, meringue, kale & Food’s good looks: for those of you preparing food on a daily basis be it for your blog or for a restaurant, it is essential that your food looks good. By using what you learned in a smart way there are several ways to help you keep your food look good!

homemade pesto

Pesto & Food Packaging

Packaging of food is a perfect example of applying all the different sciences of food in a product. Let us look into pesto packaging more closely.

(Green) pesto is made by crushing basil leaves together with cheese, pine nuts, garlic and mixing this with olive oil and spices. Of course, there are a lot of different recipes, but this is the basic version.

Commercially made pesto often contains several other ingredients for various reasons, be it increasing shelf life or reducing costs. These pesto’s are generally sold in glass jars with a lid firmly attached on top. On the label a statement will be made describing that the pesto should be stored in the fridge after the glass jar has been opened and only for a few more days.

Now that we’ve got the picture, let’s walk through this mini case study on packaging one by one.

1. Browning of pesto

Green pestos have a tendency to turn brown over time especially when home made. This is a chemical reaction catalyzed by enzymes which requires oxygen to take place.

Smart packaging preventing access of oxygen to the pesto will prevent browning to quite some extent. A closed glass jar won’t let any oxygen in.

2. Sterilization

Pestos are commonly sterilized. During this process the pesto is heated to a high enough temperature to kill of all miroorganisms. By doing sterilization in the final packaging, no cross contamination takes place.

Glass jars can resist the high heat (>100°C) of sterilization and are thus a great choice for this product.

Once the jar has been opened new microorganisms can enter again. That is why after opening the pesto has a limited shelf life in the fridge.

shelf with pancake mix boxes

Pancakes & Food Safety

Food safety is one of the most important topics for food manufacturers. Each and every food they produce should at least be safe to consume.

A food can be unsafe for various reasons. There might be a foreign product in a product (e.g. a piece of wood, risking suffocation), it can also contain harmful chemical contaminants and of course, a product might contain pathogenic microorganisms, as discussed during this course.

For now we will limit ourselves to the microbiology aspect of food safety. Let’s zoom in on this issue by discussing pancakes. In a previous post I’ve discussed the different ways of making pancakes (Dutch version can be found here):

  1. doing it youself;
  2. using a pack of pancake mix;
  3. buy ready made pancakes ready for a microwave.

All three have very different food safety risks for their producers, so let’s dive in!

Scenario 1 – Home made

When making your pancakes yourself you need milk, eggs, flour and baking powder. You are responsible for buying safe ingredients for making the pancakes. The producers of milk, eggs, flour and baking powder of course do have to deliver a safe product.

Milk is either pasteurized or sterilized. Eggs don’t need any treatment, they are protected by their shell. Eggs might have a risk of Salmonella contamination, however, baking your pancakes will heat your batter up, killing these. Flour and baking powder are too dry (too low water activity) for most pathogenic microorganisms to grow in.

Not too hard for a producer is it, especially since you’ll be mixing and combining everything yourself and using it straight away.

Scenario 2 – Pre-mix

Things start getting a little harder here. By mixing several ingredients in a pack (e.g. milk powder, flour, egg powder, baking powder) they have to be sure all are indeed of a high quality. Especialy milk and egg powder are slightly more tricky than flour and baking powder.

Nevertheless, the final product is again a dry powder so most microorganisms will simply not grow in such a product (if kept dry). Also, when making pancakes you will heat the batter, certainly killing of at least part of the microorganisms.

Scenario 3 – Microwave

These are by far the most tricky ones to make. As a food producer you have to take into account various ways of people consuming your pancakes. One of those is: cold. People might not even properly heat your pancakes before consumption. This means that the pancakes should be absolutely free of pathogenic microorganisms.

Since pancakes tend to be moist (thus high water activity) and have a quite neutral pH-value, there are a good place to grow for microorganisms. So packaging and storage are very important here.

Eggs, meringue, kale: & Food’s good looks

The last way we’ll be applying our food science today is by looking at a food’s good looks. Whether you’re making food photos for a blog or serving people food to it, you want it to look good. Unfortunately, a lot of chemistry (and also physics) doesn’t help with having your food look good.

Here are three great examples of how food can look less good because of chemistry and physics.

Grey egg yolks: Most people like their boiled egg with a white outside and a nice yellow inside. A gray/blue layer on the yolk is not appreciated. This is chemistry at play, two components react together to form this unappetizing colour! Read more about the rate of this reaction and how prevent it on my post on grey egg yolks.

Italian meringue: It’s a great example of a wonderful foam, unfortunately, it is not 100% stable. After a few days it will collapse, a great example of food physics at play.

Kale: when boiling kale leaves, or any leafy vegetable as a matter of fact, you will see that the vegetable shrinks in size very rapidly. Food chemistry and physics both play a role here. Structures are broken down by the boiling water and the ‘foamy’ leaf collapse.

That’s it for this Food Science Basics in 6 weeks course. I hope this last week has given you a good feel for applying the things you’ve learned in the past few weeks. Also, do not forget to sign up for my newsletter if this is what you enjoy learning. My blog is full of examples in which I combine food and science!


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Disclaimer: this is for educational purposes only and I cannot be held accountable for any actions taken as a result of this post. For any advice on e.g. food safety consult a local professional.