# Chemical Characterization of Cider Produced in Hardanger--From Juice to Finished Cider
## 1 Introduction  
Over the last decade, the consumption of ciders has increased worldwide. Norwegian ciders, especially ciders produced in the Hardanger region, have become popular and have received attention in international cider competitions. The Hardanger region is the leading fruit-growing area in Norway, contributing to approximately 50% of Norwegian fruit production. The typography, with orchards planted in steep hills and a mild coastal climate, makes the Hardanger fjord area suitable for growing fruit at a latitude of approximately 60\({}^{\circ}\) N. There are three milestones that are important for the increasing interest in cider from the Hardanger region: (1) in 2003, the Hardanger Cider Association was established; (2) in 2009, Cider from Hardanger became a geographically protected designation of origin; and (3) a change in Norwegian alcohol regulations in 2016, allowed cider producers to sell bottled ciders from the farm. In the period from 2012 to 2022, the sale of Norwegian cider in the state wine monopoly (Vinmonopolet) had a 20-fold increase. In 2023, the total sale of Norwegian cider (including sales at Vinmonopolet, the HORECA market, and farms) corresponded to 550,000 L. The total amount of cider produced in Hardanger sold corresponds to 80% of the total Norwegian sales. In 2023, the production of cider in the Hardanger region was approximately 700,000 L. The goal is to increase cider productionto 1 million litres in the Hardanger region by 2025 (personal communication, [PERSON], Hardanger Cider Association). The main sensory drivers in cider are phenolics such as flavan-3-ols (catechin and procyanidins); hydroxycinamic acids (5-caffeoylquinic acid or chlorogenic acid); 4-\(p\)-counarylquinic acid; dihydroachcones (phloretin); dihydroflavanols, and anthocyanins [1]; as well as organic acids and aroma compounds like esters, higher alcohols, fatty acids, aldehydes, and ketons [2]. In recent years, norisprenoids have also been confirmed in cider [2]. The sensory profiles and chemical quality of ciders are influenced by various factors, including (1) the apple cultivar; (2) orchard-related agronomic factors; (3) processing technologies; (4) fermentation conditions (alcoholic and malolactic), such as nutrition and temperature; and (5) ageing [2; 3; 4]. To achieve the cider production target, differentiating the cider and ensuring uniform sensory quality is of importance to increase sales [2]. A comprehensive study [5] analysed sensory profiles of 14 traditional and commercial ciders from Sweden, Denmark, and the UK. The researchers identified unique characteristics in industrially produced and traditionally made ciders, grouping them based on their production technology, including wood ageing, spontaneous fermentations, controlled malolactic fermentation, and industrial production with commercial yeast and addition of other fruit and herb aromas. Due to the numerous processing steps affecting cider quality, significant variation exists among products from different producers and years. Establishing product differentiation and consistent quality requires identifying the essential chemical composition contributing to the sensory quality in ciders from Hardanger. Unfortunately, limited information is available about the chemical compositions of ciders from both Hardanger and Norway [3; 6; 7]. To gain a better insight and distinguish Ciders from Hardanger, further research efforts and consistent monitoring are essential. In a groundbreaking 2024 study, researchers compared the general chemical composition of Norwegian ciders, including those from Hardanger, to selected French ciders for the first time. The samples were purchased from wine monopoly stores (Vimononopolet) in Norway [3]. Notably, the Norwegian ciders were found to be fresher and lighter than their French counterparts, with observed differences in total phenol content and aroma profiles [3].