Keeping up-to-date with instruments for the brewing industry

Campden BRI’s instrument assessment service and instrument comparison website enable staff within the food and drink industries keep up-to date with new and forthcoming instruments. The services save users time, money and effort on obtaining information and provides assessment reports that are unavailable elsewhere. New instruments are being developed all the time for the testing of food and drink and therefore it is difficult for staff within these industries to know whether a particular instrument will fulfil their requirements. Having an instrument evaluated can be costly part of doing business, as each client may request different features as part of the evaluation process.

Campden BRI’s new instrument assessment service can help keep these costs down by providing an independent evaluation of new and existing equipment. The performance of new instruments is compared against existing techniques. Instruments are also assessed on their suitability for use, including ease of use, robustness and ease of cleaning. The scope of any evaluation is viewed in advance by advisors in the food and drinks industries, thus ensuring that the assessment meets the needs of the industry. The work is carried out at Campden BRI by trained, experienced staff. Once completed, the assessment report can with permission from the client be publicised on the Campden BRI Instruments website (www.compareinstruments.com) and/or in the food and drinks press. Some of the instrument assessments which have been undertaken are summarised in this article.

Instrument assessments

Mettler Toledo Combined Densitometer/Refractometer

Density meters are widely used in the food and drinks industry for measurement of extract and gravity. Refractometers are not so widely used but in conjunction with densitometers offer a convenient route to alcohol measure – ment. The most common method for alcohol and gravity measurement is now by NIR but as a secondary technique, it would not achieve the accuracy and precision of a densitometer. The instrument is based on the vibrating tube principle widely used in density meters. The DM45 density meter and the RX40 refractive index cell module were supplied for this evaluation (Figure 1).

Figure 1: Mettler Toledo Combined Densitometer/Refractometer

In this evaluation, the Mettler Toledo instrument was tested against another make of densitometer for measurement of gravity and against the official distillation method for measurement of alcohol. The results were then compared for accuracy and precision. In the measurement of density, the Mettler Toledo instrument was shown to give comparable performance to an established instrument. In the tested range of 2 to 8.5 per cent ABV, the instrument also gave accurate measurement of alcohol, either by calculation from density values or by refractometry (Table 1). Precision values for the basic parameters are within the tolerances expected for densitometers in the brewing industry. The instrument was straightforward to use and showed good stability in operation over several days with various wort and beer samples. Table 1. Summary of analysis results for six brands of beer.

Aqualution Systems ‘Sureclean’ Beer Line Cleaner

Aqualution Systems Ltd has produced a new non-corrosive novel beer line cleaner called ‘Sureclean’ (European name – Zygosan) Sureclean is a powerful tool against microorganisms encountered in the beer dispense trade. It proved to be more effective than a standard beer line cleaner used for comparison in this study and was shown to clean beer dispense lines very effectively in a very short time. The reference cleaner reduced the microbial load of the lines by over 90 per cent, however, in most cases not by 100 per cent as was seen following the Sureclean clean (Table 2). Table 2. The percentage reduction in viable micro-organisms present on the inner line surfaces after cleaning with Sureclean and the reference cleaner (A and B refers to locations at both ends of the lines).

On comparison of the efficacy of the two cleaners, Sureclean showed to be the more effective cleaner, eliminating 100 per cent of viable aerobic microorganisms in just a third of the time it took for the reference cleaner to eliminate 93 – 97 per cent of aerobic microorganisms (Table 2). Sureclean is used straight from the container thus saving time and resources, whilst other cleaners on the market need to be diluted. Sureclean contains no chemicals so this eliminates the need for protective clothing and goggles. It does not require a COSHH datasheet therefore improving the Health and Safety of both staff and customers. Spillage of Sureclean will not result in burns to skin or bleaching of clothing and is non harmful. If accidentally swallowed, Sureclean has no undesirable side effects. Furthermore, it is environmentally friendly as it allows water savings to be made since it does not need to be diluted and does not require a water rinse at the end of the cleaning procedure.

Chemometec Nucleocounter YC-100

Chemometec A/S manufactures the Nucleo – counter YC-100 (Figure 2) for enumeration and viability testing of yeast populations. The measurement of yeast concentration and viability are important routine analyses used in breweries throughout the world. Currently, the standard method for the determination of cell concentration is by counting yeast cells under the microscope using a haemocytometer. The number of dead cells is determined by methylene blue staining. This method has been criticised as subjective and inaccurate at lower viabilities.

Figure 2 The Nucleocounter YC-100

The Nucleocounter YC-100 counts individual cells in suspension using fluorescence imaging technology. This is carried out by detecting the fluorescence signals of propidium iodide-stained DNA within the cell nuclei. The stain is only taken up by non-viable, dead cells with a damaged cell membrane. The concentration of yeast in a suspension can be determined by disrupting the cell membranes of viable yeast using a lysis buffer. In this work, a number of yeast suspensions covering a range of viabilities were measured using the traditional methylene blue method as well as the Nucleocounter YC-100 and the two compared. Also, samples were run on two different Nucleocounter YC-100 instruments to assess repeatability and reproducibility. Finally, to determine whether a range of personnel can use the instrument, an untrained operator was asked to measure the concentrations and viabilities of a set of yeast suspensions using the Nucleocounter YC-100. The Nucleocounter YC-100 and haemo – cytometer plus methylene blue method gave yeast viability measurements that showed good correlation with both lager and ale yeasts (Figure 3).

Figure 3 Comparison of the Nucleocounter and standard methylene blue methods for the determination of percentage viability of the lager yeast BRYC 32. The dotted line is y=x. The correlation coefficient relates to the solid line that has been fitted to the experimental data

Over the lower viability range, the Nucleocounter appeared to over-estimate the yeast viability. However, this effect may be more likely due to an over-estimation of the numbers of dead cells when employing the methylene blue staining method. In other words, it is probable that the Nucleocounter is better at analysing cell viability compared to the methylene blue method. Data was reproducible between separate Nucleocounter instruments and its simplicity allowed personnel to use it without intensive training, such as is required for the methylene blue test. Additionally, the speed and simplicity of its use may also result in cost savings when testing large numbers of samples, as it was considerably faster than the standard methylene blue method. With simple training, the Nucleocounter instrument is more amenable to use by brewery staff whereas the haemocytometer method requires trained laboratory staff. The Nucleocounter YC-100 is a robust instrument and will be of interest to breweries for yeast cell counts and viability, allowing rapid and reproducible results to be obtained.

Compare instruments website

Full reports of instrument assessments are available on Campden BRI’s instrument comparison website (www.compare instruments.com) which is free to use. The site was set up to provide information on instruments for use in the brewing and related industries, thus enabling staff in these industries to keep up-to-date with the latest developments. The site avoids users having to browse through many different websites to find which manufacturers produce an instrument and what variants are available. The site was initially aimed primarily at the brewing sector but is now being expanded to include suppliers from the brewing, cider, wine and food industries. There are currently 140 instruments on the site from 37 suppliers. It now also includes in-line and at-line instruments, rapid microbiology methods and dispense hygiene equipment. Figure 4 shows the homepage of the website. The left hand menu pane allows users to filter instruments by test, food type or by the manufacturer. Users who prefer to search rather than browse can do so using a keyword search; this is to be replaced in the near future by free text search engine. Any instruments and assessment reports recently added to the website are listed on the home page.

Figure 4 Screenshot of the home page of www.compareinstruments.com

For each instrument, there is a photograph to give an indication of size and complexity and a brief description detailing key points to enable the user to decide if it is suitable for their needs. There are links to access further information including:

• Manufacturer brochures and/or technical datasheets (these are updated whenever a brochure is updated)
• Independent instrument assessment reports produced by Campden BRI or other industry bodies
• Electronic links to the supplier for users to contact them directly to obtain further information on the instrument or obtain a quote

The website is continually expanding and improving. New instruments and manufacturers are being added and it is set to become the premier resource for bringing suppliers and end users together in one place. The instrument assessment service will reduce the time and cost of evaluating new instruments and the reports produced from these assessments will complement other information about the instruments on the website.  

About the Author

Catharine O’Shaughnessy has a BSc in Biochemistry with Biotechnology, an MSc in Biochemical Engineering and a Diploma in Brewing. In 2005, she was awarded the IBD Cambridge Prize for her work at Campden BRI in the areas of malting, cereal roasting, malt flavour chemistry and the sensory modelling of malt flavour. In 2007, she joined the Sensory team where she managed the expert technical taste panels. At the beginning of 2011, Catharine was appointed Manager of the Instrument Assessment Programme. She is the author and co-author of a number of scientific publications in international journals.