Why Freshness Matters in Crisp Production
It is estimated that, on average, UK consumers eat as many as 150 packets of crisps each year and the UK crisp market is valued at a whopping £2+ billion per year, so it’s no surprise there is a huge amount of science and technology behind the humble crisp. In an overcrowded market, crisp manufacturers have to guarantee satisfaction to the end consumer and Control Metrix plays a role in delivering the perfect crisp. In this article, we’ll discuss the different technologies that form part of the crisp manufacturing process — why moisture levels are so crucial, the role of nitrogen, how a crisp factory can judge if it has the fat content just right and how the packaging can be tested.
The Science of Oil and Moisture in Crisps
Moisture Control for Long-Lasting Freshness
It’s easy to assume that moisture is the enemy of the crisp. After all, as consumers, we expect a perfectly crisp, crisp! And it’s true — after frying, baking or roasting, most of the moisture has been lost. However, there needs to be a tiny bit of moisture retained by the crisp — otherwise, it would be too hard. Too much moisture and it would lose its crunch. An extremely fine balance is involved — and measuring that balance is an essential part of the manufacturing process. To retain the perfect balance of flavour profile and ideal freshness, moisture levels need to be monitored. The Series 9 NIR Food Moisture Gauge is the ideal piece of equipment to give operators key insights into these variants, all without creating waste through damage. 
As crisps pass along the production line, the gauge will measure the moisture level (along with other constituents such as oil) and immediately alert a change in levels, thus reducing any wastage. The measurement sensor works on the principle that moisture molecules within the crisp will absorb a certain wavelength of Infrared (IR) light. By emitting these wavelengths onto the test subject, the non-absorbed, rebounding light can be measured, determining exactly how much wavelength is being absorbed, therefore, providing a moisture calculation.
Oil Content and Its Impact on Quality
Crisp packets must visibly display oil content for consumers and, in some cases, provide evidence of low-fat content, so they must be accurately measured. As well as the Series 9 Food Moisture Gauge, which can determine oil content in the same way as crisp moisture measurement, Control Metrix can also offer the InfraLab Series 9 NIR Food Analyzer. This equipment operates on the same principle — NIR light is beamed into the product, which then calculates the level of oil or fat based on the absorption of reflected light. The InfraLab is a much smaller piece of equipment often used in product development. It is easy to use, with analysis taking just five seconds. It is also non-contact, so it doesn’t damage the food sample in any way, and it can store up to 100 thousand sample files, allowing data to be stored for quality audits.
How Nitrogen Keeps Crisps Fresh
Preserving Freshness with Nitrogen
Once crisps are off the production line and accurate oil and moisture measurements are reached, how does the crisp manufacturer keep them in perfect condition until they reach the end consumer? This is where chemistry plays an essential part. All that “air” in a crisp packet is, in fact, nitrogen — a necessary contributor to a fresh crisp! Nitrogen minimises any reaction with the crisp ingredients, helping them to stay fresh. Once a crisp is exposed to the air, it will slowly start to lose its freshness and become soggy and eventually stale. The nitrogen will keep the moisture at the correct level and prevent the oil from deteriorating when exposed to air, resulting in a rancid taste.
Protecting Crisps During Transport
Nitrogen also plays an important role in cushioning the product. Crisps are fragile and need to be protected on the journey to the end consumer, so the nitrogen keeps the crisps from looking like a bag of breadcrumbs once transported, stored, displayed, bought and finally opened.
Package Leak Detection for Seal Integrity
Why Seal Integrity Matters
But if you’ve ever opened a packet of crisps and found them crushed, soggy or stale, the nitrogen has leaked, allowing oxygen to get into the packet. So for a crisp manufacturer, another crucial part of the process is ensuring the packets are leak-proof and have a robust seal. Leak detection and seal integrity testing are the surest ways to determine this.
Advanced Vacuum Decay Testing
The Sealtick TSE 6086b Package Vacuum Decay Seal Integrity Tester is relied upon by many crisp manufacturers to detect tiny leaks through pressure decay or vacuum testing. A sample of crisp packets is placed inside a vacuum chamber and then sealed to isolate the contents from the external atmosphere. Then, a vacuum pump removes air from the chamber, creating a low-pressure environment. The pressure difference between the inside of the crisp packets and the chamber causes the packets to expand slightly, allowing them to be inspected for the tiniest leaks or defects. Such testing doesn’t harm the packets in any way, so they can be returned to the production line, and with a pass or fail result in 15 seconds, it offers constant reassurance to manufacturers that their packaging is robust enough to keep crisps at the highest quality.
So, the next time you enjoy a packet of crisps, you can rest assured that every effort has been made to get them to you as fresh as possible and science has been applied to provide the perfect crunch and taste.
Control Metrix Solutions for the Snack Industry
If you would like any more details about the technology involved in food manufacturing, get in touch with Control Metrix to see how we can help. Our product specialists can help you find the right non-contact NIR moisture measurement equipment for your application.
Frequently Asked Questions about Crisp Freshness
How do manufacturers keep crisps fresh in the packet?
Manufacturers flush packets with nitrogen gas to replace oxygen, which slows down the staling process and keeps crisps crunchy. Nitrogen also helps maintain the correct moisture balance, preventing sogginess or rancidity.
Why is nitrogen used instead of normal air?
Normal air contains oxygen, which reacts with the oils in crisps and causes them to spoil. Nitrogen is an inert gas that prevents these reactions and also cushions the crisps during transport, protecting them from damage.
How is seal integrity tested in crisp packaging?
Seal integrity is tested using vacuum decay or pressure decay methods, which detect even the tiniest leaks. Systems such as the Sealtick tester allow packets to be checked quickly without damaging them, ensuring they remain airtight until they reach the consumer.
