Characterization of the Flavor Profile of Bigeye Tuna Slices Treated by Cold Plasma Using E-Nose and GC-IMS

To avoid heat, treatment induces numerous physicochemical changes under severe conditions in the tuna, cold plasma (CP), as a non-thermal technology, possess objective potential on tuna processing. The effect of cold plasma on the volatile flavor compounds of bigeye tuna (Thunnus obesus) sashimi has been evaluated using electronic nose (E-nose) and gas chromatography-ion mobility spectrometry (GC-IMS). GC–IMS results revealed a total of 33 volatile compounds in tuna slices. The effect of CP treatment on tuna flavor was not significant, furthermore CP could protect volatile freshness compounds such as 1-hexanol. Principal component analysis (PCA) of the E-nose and GC–IMS results could effectively differentiate the effect of storage to tuna sashimi. There was a high correlation between the E-nose and GC–IMS results, providing a theoretical basis for establishing the flavor fingerprint of tuna sashimi.

Effect of Production Technique on Pilsner-Style Non-Alcoholic Beer (NAB) Chemistry and Flavor

The sensory, volatile, and physiochemical profiles of nineteen commercial non-alcoholic pilsner-style beers produced by different production techniques were analyzed and compared with a dry-hopped non-alcoholic IPA. NABs made only with either physical dealcoholization or restricted fermentations differed significantly in chemistry and flavor. Generally, NABs produced by restricted fermentations were the most worty, thick, and sweet, whereas NABs that were physically dealcoholized had the lowest taste/aroma intensities and were the sourest, most thin, and least sweet. Interestingly, the method of dealcoholization had a minor impact on the flavor profile. The use of maltose intolerant yeast as well as the implementation of combined treatments, such as blending dealcoholized beer with beer containing alcohol, were the techniques found to produce NABs with more harmonious and multifaceted chemical and flavor profiles. NABs with increased hop aroma volatiles were the most harmonious, particularly highlighted by the NA IPA reference. Even though dry-hopped character might be atypical for pilsner-style beer, dry-hopping appears as a simple application to produce NABs with more harmonious flavor.

Finding correlations between hop catalogs and real hoppy character in brewery conditions

Brewing recipe design is mainly based on brewer’s expertise, information available in catalogs and certificates of analysis (CoA’s). Hop schedule design and formulation has become an essential topic since hoppy craft beers took the scene. But how accurate is the flavor profile information provided in catalogs? How useful is the chemical composition profile information in CoA’s? Besides current research and tons of reported experiences, hops impact is still a mystery, and topics like biotransformation are black-boxes for brewers. In this study, nine single hopped beers were brewed, and a trained panel conducted sensorial beer analysis. Then, to asses hop impact, qualitative and process-related-quantitative beer characteristics were contrasted to find valuable correlations and trends between hop catalogs and final beers. Discrepancies with catalog qualitative data were reported. In addition to what is already described in the literature, here we describe how α-acids, linalool, myrcene, and geraniol (despite the classical use for these compounds) could predict positive and negative hop impact of nine different hop varieties on bitterness, flavor, and aroma, when they are applied in different brewing process steps. Also, with this pipeline we stand the basis of a tool to be improved, available for brewers, to better predict their brews and assess new hop varieties in real-life pilot brewing set ups.

Microbial communities in retail draft beers and the biofilms they produce

In the beer brewing industry, microbial spoilage presents a consistent threat that must be monitored and controlled to ensure the palatability of a finished product. Many of the predominant beer spoilage microbes have been identified and characterized, but the mechanisms of contamination and persistence remain an open area of study. Post-production, many beers are distributed as kegs that are attached to draft delivery systems in retail settings where ample opportunities for microbial spoilage are present. As such, restaurants and bars can experience substantial costs and downtime for cleaning when beer draft lines become heavily contaminated. Spoilage monitoring on the retail side of the beer industry is often overlooked, yet this arena may represent one of the largest threats to the profitability of a beer if its flavor profile becomes substantially distorted. In this study, we sampled and cultured microbial communities found in beers dispensed from a retail draft system to identify the contaminating bacteria and yeasts. We also evaluated their capability to establish new biofilms in a controlled setting. Among four tested beer types, we identified over a hundred different contaminant bacteria and nearly twenty wild yeasts. The culturing experiments demonstrated that most of these microbes were viable and capable of joining new biofilm communities. From these data, we provide an important starting point for the efficient monitoring of beer spoilage in draft systems and provide suggestions for cleaning protocol improvements that can benefit the retail community.