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Transition metals, including copper, iron, and manganese, are known to catalyze the generation of reactive oxygen species (ROS) in beer leading to reduced product stability. Metals in beer are generally derived from raw ingredients. The present study aims to evaluate the impact of brewing and dry-hopping using hops treated with copper-based fungicides (CBFs) on the final transition metal content of model buffer solutions and pilot-scale systems of wort and beer. Copper levels in model wort and beer solutions were elevated (105.6% and 230.4% increase, respectively) when CBF-treated hops were used. In laboratory-prepared wort, elevated copper concentrations were not observed when CBF-treated hops were used for boiling. Dry hopping of beer using CBF-treated hops led to significant increases in total copper content (ca. 75 µg/kg vs. ca. 40–50 µg/kg in the control-hopped beer) when yeast was absent from the treated beer, but not when yeast was present. It was observed that manganese levels were significantly elevated in all hopped beers (ca. 495–550 µg/kg vs. 90–125 µg/kg in the unhopped control), regardless of hop treatment. A hop varietal thiol, 4-Mercapto-4-methylpentan-2-one, was spiked into treated beers, and the rate of oxidative loss was monitored during aging. Rates of thiol loss in treated beer samples did not differ across CBF treatments but were significantly lower in unhopped controls in the absence of yeast (p < 0.0001) and correlated significantly with total manganese content of the beers (R2 = 0.4228, p = 0.0006). The rate of staling in hopped beers as measured by the rate of 1-hydroxyethyl radical generation did not differ among hop treatments, suggesting that excess copper content contributed from the hops does not negatively impact the oxidative stability of the beers. These findings suggest that brewers can use CBF-treated hops without any negative implications for the shelf stability of their beers and do not contraindicate the use of CBF in hops production when necessary.

Potatoes are an important food crop that undergo postharvest storage, reconditioning, and cooking. Colored-flesh varieties of potatoes are rich in phenolic acids and anthocyanins. Previous studies have suggested that purple-flesh potatoes can inhibit colon cancer cells in vitro and reduce colon carcinogenesis in vivo. Vacuum frying (VF), as an alternative to conventional frying (CF), reduces fat content and may promote polyphenol retention in potato chips. We examined the impacts of reconditioning (storing at 13 • C for 3 weeks following the 90-day cold storage at 7 • C) and frying method on phenolic chemistry and in vitro colon cancer stem cell (CCSC) inhibitory activity of purple-flesh potato chips. We found that reconditioned chips exhibited higher total phenolic content (TPC) than nonreconditioned chips. We found that VF chips had lower TPC than CF chips. We observed no interaction between treatments. We found that VF chips had 27% higher total monomeric anthocyanin levels than CF chips, and observed a significant interaction between treatments. We found that VF chips had higher concentrations of caffeic acid (42%-72% higher), malvidin (46%-98% higher), and pelargonidin (55%-300% higher) than CF chips. We found that reconditioning had no effect. We found that VF chips had greater in vitro CCSC inhibitory activity than CF chips. Our results suggest that VF can improve the phytochemical profile and health-related functionality of purple-flesh potato chips, but additional studies are needed to determine if these results translate to the in vivo situation.

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