Near Infra-Red (NIR) spectroscopy was determined to be the most suitable method to replace traditional hop chemistry methods. HPA have built very robust predictive models in partnership with Sagitto. These models can now produce hop chemistry measurements of sufficient accuracy to eliminate the need for solvent analysis of pre-harvest maturity, bale condition and experimental varieties, resulting in a 70% reduction in solvent use and waste.
As well as slashing their use of solvents, HPA have greatly reduced their reliance on other analytical methods - ones that are both very time consuming and energy intensive (such as oven drying for moisture, and oil distillation). NIR now accounts for the bulk of HPA’s internal hop analysis requirements and has been rolled out across all three laboratory sites while being fully integrated into HPA's Laboratory Information Management system.
The hop sampling and measurement process spans a period of six months. During this time, HPA go through three phases on quality testing – pre-harvest in-field samples, harvest bale samples and post-harvest packaged product samples. HPA analyses around 3,000 hop samples over the course of harvest, comprising more than 25,000 measurements.
Pre-harvest sampling tracks the development of hop cones and the accumulation of alpha acids and essential oils across HPA's farms. They systematically sample every paddock across the farms at least three times pre-harvest, with the final sample taking place within 36 hours of the paddock being harvested. The information that they receive from these samples confirms whether their planning around harvest logistics is correct, and informs the picking sequence for varieties that cover significant acreage. This picking sequence ensures they capture the best possible representation of each variety year-on-year.
Data from Sagitto's miniature NIR spectrometers is fed into proprietary predictive models to assess the samples’ alpha acids and oil content. Gland fill, dry matter and cone weight are also measured at this stage. All of these measurements follow a fairly consistent pattern of development in the lead up to harvest, which occurs when the paddock reaches ideal values.
During harvest HPA take several composite samples from each lot of hops once they have been baled. Alpha acids and moisture content are the main focus at this point with all measurements produced through NIR. This is crucial to the blending process, enabling HPA to achieve consistent quality outcomes for each variety year-on-year.
HPA conducts further testing on each lot of final packaged product, including pellets and flowers, for inclusion in the certificates of analysis (CoAs). For the moment, this analysis has to be made using traditional 'wet chemistry' reference methods that are accepted by the international community. HPA, as part of the global Barth Haas Group, is working towards the day when NIR is an accepted method for CoAs, to further reduce reliance upon organic solvents.
