A quantitative and qualitative assessment of terpenes in the manufacturing of Cannabis-infused and highly hopped SA craft beers

Abstract

The increasing global interest in functional beverages has extended to beer, where bioactive plant compounds are being harnessed to provide perceived health benefits alongside sensory appeal. Within this context, hops (Humulus lupulus) and Cannabis sativa, two members of the Cannabaceae family, share significant chemical and aromatic similarities through their terpene content. This study explored the quantitative and qualitative assessment of terpenes in the manufacture of Cannabis-infused and highly hopped South African craft beers. The work was motivated by the absence of verified data on the survival, retention, and potential bioactive contribution of terpenes in the final product, despite widespread claims of their presence in such beers. The study aimed to determine whether terpenes originating from hops and Cannabis are retained after brewing, at concentrations that may contribute to health or sensory benefits. The specific objectives were to: (1) analyse and compare terpenes between raw materials and finished commercial beers; (2) assess the chemical composition of these beers using validated chromatographic methods; (3) brew experimental beers incorporating hop and Cannabis extracts to enhance terpene retention; and (4) evaluate the sensory acceptability of the resulting beers. Commercial samples of highly hopped and cannabis-infused beers, as well as their corresponding raw materials (hops, hop oils, Cannabis terpene concentrate, and CBD oil), were characterised using Gas Chromatography coupled with Flame Ionisation Detection (GC-FID), Gas Chromatography-Mass Spectrometry (GC-MS), and High-Performance Liquid Chromatography (HPLC). These methods enabled the detection, separation, and quantification of volatile terpenes and cannabinoids across different matrices. The compounds detected in the raw materials were not retained in the finished beers. Lager 1 in which shelled hemp seeds were used, only terpinolene was detected in the final beer. Lager 2 in which an CBD oil with content CBN, Delta-9-THC, THC-V and total potential THC at levels 0.004, 0.005, 0.001 and 0.005% respectively, was used contained none of the compounds in the finished beer. Pale ale 1 in which commercial Cannabis terpene extract was used that contained 9 terpenes namely α -Humulene (157.622 mg/g), α -Pinene (64.453 mg/g), β -Caryophyllene (202.573 mg/g), β -Myrcene (151.144 mg/g), β -Pinene (36.156 mg/g), limonene (54.502 mg/g), linalool (19.981 mg/g), ocimene (37.426 mg/g), and terpinolene (58.745 mg/g). The finished beer contained only terpinolene (0.249 mg/g). Analysis of highly hopped beers from the same breweries also yielded similar results. Raw materials (hops) contained high levels of terpenes, but only terpinolene was detected in 2 of the 3 finished beers. Experimental brewing trials were then conducted using hop oils distilled from up-cycled South African hop waste and Cannabis terpene extract. Controlled fermentation and late-stage hop oil additions (0.03 g/7 L) were applied to minimise terpene volatilisation losses. Three pilot brews (PZB-01, PZB-02, PZB-03) were produced, representing hop-oil and cannabis extract treatments, and were evaluated through sensory sessions with trained beer judges/tasters (n = 22) as well as analysed using GC-FID. Sensory analysis of experimental beers attributed medium low aroma and flavour to fruity, hoppy apple, pear, orange, lemon and earthy when the median of test results was considered, with little differences among the 3 beers. Overall acceptability of PZB-02 (Cannabis terpene concentrate and PZB-03 (African Queen hop oil) was high (score of 8 on hedonic scale). These results indicated that the concentration of oils used required optimization and could be increased. Interestingly, the GC-FID analysis of the experimental beers again only detected the presences of terpinolene in PZB-01 (0.301±0.022 mg/g), PZB-02 (0.355±0.006 mg/g) and PZB-03 (0.362±0.026 mg/g) in the finished beers. Terpinolene is a structural isomer of limonene and presents as fresh, pine, herbal, woody and resinous. Its aroma profile may explain the comparable sensory results while no other terpenes were detected in the finished beer. Terpene retention primarily influences sensory quality rather than bioactivity of beer. The results provide a scientific basis for future formulation of functional or sensory-enhanced beers and support the potential of up-cycled South African hop extracts as sustainable flavouring agents in the craft brewing sector.