Conventional and innovative extraction technologies to produce food-grade hop extracts: Influence on bitter acids content and volatile organic compounds profile.

Hop extracts represent a natural alternative to synthetic food additives because of their high content of bitter acids and volatile organic compounds (VOCs) with bittering, flavoring, and antimicrobial properties. However, broader uses of hop extracts as natural techno-functional ingredients rely on the identification of sustainable and affordable extraction technologies allowing to diversify the processes and produce extracts characterized by different compositions and, consequently, qualitative properties. Thus, this study is aimed to evaluate and compare the effect of innovative and conventional extraction methods on the bitter acids content and VOCs pattern of food-grade ethanolic hop extracts for food applications. Innovative extractions were carried out by using two ultrasound systems (a laboratory bath [US] and a high-power ultrasound bath [HPUS]), and a high-pressure industrial process (high hydrostatic pressure [HHP]). Conventional extractions (CONV) were performed under dynamic maceration at 25 and 60°C; for ultrasound and conventional methods, the effect of the extraction time was also investigated. Among the extracts, the highest and lowest content of bitter acids was found in CONV 60°C extracts, and HHP and CONV 25°C extracts, respectively. Of the 34 VOCs identified in dry hops, ∼24 compounds were found in US, HPUS and CONV extracts, while only 18 were found in HHP. CONV extractions showed higher selectivity for sesquiterpenes, while US and HPUS showed higher selectivity for esters and monoterpenes. Hierarchical cluster analysis (HCA) and partial least squares-discriminant analysis (PLS-DA) allowed classifying hop extracts based on the extraction methods and also allowed highlighting the technological conditions to produce hop extracts with specific techno-functional and flavoring properties. PRACTICAL APPLICATION: The study showed that different extraction methods can lead to hop products with varying sensory and functional properties. By selecting the right extraction method, companies can produce hop extracts with specific compositions that meet their needs for clean label and sustainable food products, as well as new edible packaging or coatings.

Antioxidant and pro-oxidant phytochemicals in ultrasound and microwave assisted extracts from hop cones: a statistical modelling approach.

The present study investigated the relationships between different green extracts from hop cones (HGEs) and their cytoprotective/cytotoxic effects on human cultured colonocytes, using a multivariate statistical approach. HGEs were obtained by ultrasound (US) and microwave (MW) assisted extraction, using food grade solvents (ethanol and ethanol : water = 50 : 50 mixture). Their chemical fingerprinting showed the presence of 21 bioactive compounds belonging to the classes of polyphenols, prenylcalcones and floroacylglucinols, which were more abundant in MW ethanolic extracts. All the extracts, except for the US hydroalcoholic one, exerted a cytotoxic effect in a dose-dependent manner. HGEs did not alter the cellular redox status at low doses, while at the highest concentrations considered they displayed a pro-oxidant or antioxidant activity. Chemometric analysis revealed the compounds most correlated with cellular toxicity and/or ROS production and that the differences observed in Caco2 cells could be adequately explained by 2D statistical models including inhibitor-promoting agent pairs.

Hop Leaves as an Alternative Source of Health-Active Compounds: Effect of Genotype and Drying Conditions.

In hop cultivation, one-third of the crop is a valuable product (hop cones), and two-thirds is unexploited biomass, consisting mainly of leaves and stems, which, in a circular economy approach, can be recovered and, once stabilized, supplied to industrial sectors, such as cosmetics, pharmaceuticals and phytotherapy, with high added value. In this regard, this study aimed to investigate the effects of two different drying methods: oven drying (OD) at 45 °C and freeze-drying (FD), on the overall nutraceutical profile (i.e., total phenols, total flavans and total thiols), pigment content (i.e., carotenoids and chlorophylls) and the antioxidant potential of leaves from five different Humulus lupulus varieties grown in central Italy. Moreover, attenuated total reflectance infrared (ATR-FTIR) spectroscopy was applied to dried leaf powders to study the influence of both the variety and treatment on their molecular fingerprints. The spectral data were then analyzed by principal component analysis (PCA), which was able to group the samples mainly based on the applied treatment. Considering the overall phytochemical profile, FD appeared to be the most suitable drying method, while OD provided higher carotenoid retention, depending on the genotype considered. Finally, unsupervised chemometric tools (i.e., PCA and hierarchical clustering) revealed that the two main clusters contained subclusters based on the drying treatment applied; these subgroups were related to the susceptibility of the variety to the drying conditions studied.

Humulus lupulus Cone Extract Efficacy in Alginate-Based Edible Coatings on the Quality and Nutraceutical Traits of Fresh-Cut Kiwifruit.

In this work, an innovative coating strategy that is able to prolong the shelf-life of fresh-cut kiwifruit was proposed, and the effectiveness of the procedure was evaluated for a period of ten days under cold storage (4 °C). Alginate (2% m/v) functionalized with green extracts from hop (Humulus lupulus L.) cones (HE; 0.5 and 1%, v/v) was used as a coating material in order to assess the best performing strategy, leading to the most stable product. At the concentrations used to formulate the edible coatings, no contribution related to hop bitterness on the final product was recorded. The results were compared to control samples (without edible coating and coated only with alginate at 2% m/v). The plant extract was characterized by its main chemical traits and by 1H NMR profiling, revealing the presence of antioxidant and antimicrobial bioactive compounds (i.e., alpha and beta hop acids, xanthohumol). Furthermore, the characteristics of the samples during cold storage were evaluated by physico-chemical (i.e., weight loss, soluble solid content, titratable acidity, pH, color attributes) and nutraceutical (i.e., total polyphenol, ascorbic acid content, total carotenoids, chlorophylls) traits. The results showed that the incorporation of hop extracts into the edible coatings tested was able to preserve the quality and nutraceutical traits of fresh-cut kiwifruit during cold storage, thus prolonging their shelf life and marketability.

Use of Conventional and Innovative Technologies for the Production of Food Grade Hop Extracts: Focus on Bioactive Compounds and Antioxidant Activity.

This study investigated the use of conventional and innovative extraction methods to produce food-grade hop extracts with high antioxidant capacity and content in bioactive compounds. Conventional extractions (CONV) were performed under dynamic maceration at 25 and 60 °C; innovative extractions were performed using two ultrasound systems, a laboratory bath (US) and a high-power ultrasound bath (HPUS), and a high-pressure industrial process. For CONV, US, and HPUS extractions the effect of the extraction time was also tested. Experimental results showed that extraction method, temperature, and time affect to a different extent the phenolic profile and have a significant effect (p < 0.05) on the total phenolic content, total flavonoid content, antiradical capacity (ABTS), chlorophyll α, and total carotenoids content. Overall, US and CONV 60 °C extractions showed the highest extraction efficiency for almost all the investigated compounds, however, the extraction method and time to be used strongly depends on the target compounds to extract.

Tasting the Italian Terroir through Craft Beer: Quality and Sensory Assessment of Cascade Hops Grown in Central Italy and Derived Monovarietal Beers.

The present study aimed to chemically and sensorially characterize hop samples, cv Cascade, grown in two different Italian regions (Latium and Tuscany) as well as their derived beers by a multi analytical approach. Significant differences in bitter acid, oil and polyphenol content were observed for hop samples according to their origin. Gas chromatography-olfactometry analysis pointed out floral notes for Tuscany samples, where hops from Latium were characterized by spicy and resinous notes, correlated to the presence of sesquiterpenes. Differences in the molecular fingerprinting were also highlighted by Fourier-Transform Infrared Spectroscopy. The differences found in the hops were reflected in the beers, which were clearly recognized as distinct by a sensory panel. Both beer samples were mainly characterized by six aroma compounds (linalool, geraniol and ß-damascenone, citronellol, 2-phenylethyl acetate, and 2-phenylethanol), three of which were potentially responsible for the geographic origin of the hops given their significantly different concentrations.

Phytochemical Profile, Antiradical Capacity and α-Glucosidase Inhibitory Potential of Wild Arbutus unedo L. Fruits from Central Italy: A Chemometric Approach.

Nowadays, there is a growing interest in botanicals for human nutrition and care. Arbutus unedo wild berries are edible and medicinal fruits that contain many healthy bioactive components, which can be considered a valuable resource for the food ingredient market and for nutraceutical and cosmetic sectors. In the present study, the polyphenols and in vitro antiradical and hypoglycemic activities of five wild Italian accessions of A. unedo were investigated, and their chemical profiles were treated by means of unsupervised chemometric techniques like the hierarchical and principal component analysis. Moreover, Fourier-transformed mid-infrared spectroscopy was used to provide a rapid assessment of the phytochemical composition of different accessions. Samples differed mainly in their anthocyanin content and overall nutraceutical potential. Anthocyanins were present mainly as glycosides of cyanidin and delphinidin, with delphinidin-3-O-glucoside being the most abundant one, ranging from 49 ± 1 to 111 ± 3 mg g-1 (for P1 and P2, respectively; p < 0.05). Extracts were screened for their in vitro biological activities by using the 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+), 2,2-diphenyl-1-picrylhydrazyl (DPPH•) antiradical tests, while their hypoglycemic activity was investigated by the α-glucosidase inhibition test. In both in vitro antiradical tests, the highest capacity was recorded for P2 (EC50: 1.17 and 0.064 mg mL-1, for DPPH• and ABTS•+, respectively), with values higher than those reported in the literature for A. unedo fruit extracts. P2 also showed the highest inhibition power towards α-glucosidase (about 70%). Moreover, the nonparametric correlation analysis pointed out a very high significant correlation between the percentage of α-glucosidase inhibition and cyanidin-3-O-rutinoside (r: 0.973; p < 0.01). Finally, the application of hierarchical analysis to samples analyzed provided three different clusters based on the average phytochemical content coded as low, medium and high. Moreover, principal component analysis made it possible to establish similarities among the accessions depending on their overall nutraceutical characteristics and on the relative anthocyanin content.