The water within

It’s not just the method, but also the reagents that matter when it comes to water content measurement in the food sector

Being able to measure and monitor the water content of food is an essential part of the food production process. Too much or too little water affects the physical and chemical aspects of food, impacting on the appearance, texture and even flavour of a product.

In confectionary, for example, the water content of caramels dictates the perfect chew (this would be a moisture content of between 4-8%) and for jellies there’s a ‘sweet spot’ for the perfect gum-like texture, which is relatively high at between 14-18%. Water levels also affect microbial activity in food materials, with moisture-rich food more prone to microbial attack, leading to early rotting and damage, in turn affecting shelf life. Plus with legal limits on water content in many food products (for example, cheddar cheese cannot contain more than 40% water) this testing also helps ensure compliance.

Furthermore, knowledge of water content in food materials is also useful in predicting their behaviour throughout the processing line, ensuring problem-free production of goods as the materials move through mixers, dryers, piping and packaging machinery. Although an everyday part of the production process, clearly the importance of water content measuring in the food and drink sector cannot be overlooked, especially with today’s consumers more savvy about food quality than ever before. Several testing methods are available, but the most broadly applied technique for water content determination is the Karl Fischer titration. It is a fast, accurate and reliable method used across a myriad of sectors from food through to pharma, chemical and petrochemical.

Being able to measure and monitor the water content of food is an essential part of the food production process.

Karl Fischer titration is so widely used because it has significant advantages over conventional drying techniques. When food samples are heated and dried, this can generate additional water due to reaction between amino acids and reducing sugars (the Maillard reaction). That additional water is also being measured giving a false (too high) result. In addition, volatile components contained in the food samples would evaporate and also bias the loss on drying result, whereas Karl Fischer titration is not influenced by volatile components, negating this issue. This makes the method the most accurate and reliable for food processing and production businesses.

In today’s competitive market, production speed and food quality is of the essence and food companies want their results to be as accurate and as quick as possible. To match this speed they require high quality reagents.For Karl Fischer titration Hydranal has become a generic brand, similar to Xerox, Kleenex or Hoover, and is globally recognised for its quality and lot-to-lot consistency. Such reagents help to speed up the testing process by increasing dissolution of samples using special working media and other troubleshooting reagents.

It’s also important to look for chemical producers that provide Certified Reference Materials (CRMs).

However, as important as these reagents are, the industry needs more than just access to a catalogue of high-purity chemicals. They now need to look for a chemical producer that can provide a real partnership by understanding their business, meeting their personalised needs and providing bespoke product support whenever needed. When choosing a chemical partner to work with, food and drink producers need to look for a company that has industry know-how and will understand their needs and be able to respond accordingly. By doing so, they’ll begin a relationship with a trusted organisation that accompanies them all the way from R&D through to production and quality control.

[caption id="attachment_56811" align="alignnone" width="430"] The amount of water is directly linked to the shelf life and quality of products.[/caption]

It’s also important to look for chemical producers that provide Certified Reference Materials (CRMs). These serve as reference points that are traceable to another internationally accepted standard, but also have a well-defined mass fraction and a properly calculated measurement uncertainty – reported in a detailed Certificate of Analysis (CoA). By choosing such a partner, analytical results will always be reliable and traceable to internationally accepted references.  Many labs use pure water for the calibration of their instruments. However, depending on the balance used, the volume of the burette, the titrant and the know-how of the user, it can be a very challenging task to produce accurate results due to very small water volumes used. For that reason, it is recommended that the instrument be calibrated with a water standard that has a much lower water content thus volumes used are much more convenient to handle.

Food producers’ results are directly affected by the quality of the reference material they use, and the choice of the right CRM producer is a matter of trust. One important indicator of the technical and administrative competence of a CRM producer is its inspection and accreditation by an independent authority. With this in mind it is well worth noting that the ISO/IEC 17025 (general requirements for the competence of testing and calibration laboratories) in combination with ISO Guide 34 (general requirements for the competence of reference material producers) represent the highest achievable level of quality assurance and is also called the ‘Gold Standard Accreditation’ for CRM producers. Hydranal Technical Service completed such double accreditation in 2014.

Food producers rightly demand accurate and timely water content measurement – their livelihoods and reputations are reliant on this. Today’s labs looking for consistent and easy-to-use water determination method that optimise their use of time whilst maintaining accuracy need search no longer.  Implementing Karl Fischer titration with the latest reagents will allow them to optimise their processes whilst retaining accuracy, but the key is to think bigger. By choosing the correct chemical production partner, food and beverage companies give themselves access to a one-stop shop that will offer the best possible support throughout their production line, whilst being sure that their analytical results will always be reliable and traceable to internationally accepted references.

Author: Soeren Hoegh is Global Marketing Manager at Honeywell Research Chemicals