Investigation and identification of foreign turbidity particles in beverages via Raman micro-spectroscopy
- PDF / 1,629,536 Bytes
- 13 Pages / 595.276 x 790.866 pts Page_size
- 89 Downloads / 180 Views
ORIGINAL PAPER
Investigation and identification of foreign turbidity particles in beverages via Raman micro‑spectroscopy Eva‑Maria Kahle1 · Martin Zarnkow1 · Fritz Jacob1 Received: 1 September 2020 / Revised: 24 October 2020 / Accepted: 31 October 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Cloudiness, opalescence or a milky appearance in beverages is usually undesirable and lead the consumers to assume that the product is of lower quality. Many different types of formation and entry can lead to cloudiness and these causes can be divided into two major categories: beverage-specific, where the ingredients cause an interaction, and external influences such as process errors or particles interacting with the medium. This study considers two main sources of external influences. Raman micro-spectroscopy (RMS) was used to detect, evaluate and validate filter aids, stabilisers and various microplastic (MP) particles. A suitable sample preparation was developed, membrane filters were tested, and a filtration method for isolating the individual particles was established and implemented. To identify particles with RMS and for better representation, a few particles were selected and the results were validated using cluster analysis and the similarity matrix. The different media influences were identified by analysing the particles both dry, in water and beer. The filtration residue after membrane filtration was also analysed. A two-dimensional image scan of the particles served to determine particle homogeneity. The spectra were then recorded with single-point scans. The polyvinylpolypyrrolidone (PVPP) spectra in the different media showed similarities greater than 80%, usually greater than 95%. The cellulose spectra showed no differences between the different media, but consistently high average similarities of 94.5%. This investigation should show that foreign particles can be detected and evaluated by RMS with suitable sample preparation and recording. Keywords Turbidity · Beer · Beverages · Filter aids and stabilisers · Microplastic · Raman
Introduction In addition to the turbidity that occurs due to the raw material, the colloids that cause turbidity must also be taken into account, which are caused by particles that are foreign to beer. The presence of beer-extraneous turbidity particles usually indicates errors in process control, e.g. when particles from filter aids or stabilising agents break through the filter medium due to pressure surges. In addition to filter aids and stabilisers, other particles with the potential to form turbidity can also occur in breweries [1–4]. In this context, label fibres, lubricant residues from the lids of beer cans as well as plastic abrasion or microplastics from conveyor belts, membranes, valves, pipes or seals should be mentioned. The * Eva‑Maria Kahle [email protected] 1
Forschungszentrum Weihenstephan für Brau- und Lebensmittelqualität, Technische Universität München, Alte Akademie 3, 85354 Freising, Weihenstephan, Germany
MP particle
Data Loading...
