Julian Karaulli

Dr. Julian Karaulli

Food Research Centre, Agricultural University of Tirana, Tirana, Tiranë, Albania

Research Focus & Metrics

Academic Career Length

5Years (2022-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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8 October 2024 in Fermentation
Verified
Journal Article
Open access
PDF file
JKJulian Karaulli
Julian Karaulli
NXNertil Xhaferaj
Nertil Xhaferaj
FCFrancesca Coppola
Francesca Coppola
BTBruno Testa
Bruno Testa
FLFrancesco Letizia*
Francesco Letizia*
Massimo IorizzoMassimo Iorizzo
Massimo Iorizzo
Several studies in recent years have shown that the use of non-Saccharomyces yeasts, used both in single and in mixed fermentations with Saccharomyces cerevisiae, can help produce craft beers with distinctive compositional characteristics. The aim of this study was to evaluate the suitability of three Metschnikowia pulcherrima strains, isolated from Albanian vineyards, for use as starters in the brewing process. Because of its specific enzymatic activities (protease, β-glucosidase, and β-lyase) and its low production of hydrogen sulfide, M. pulcherrima 62 was selected as a starter culture for the production of craft beer. Specifically, the suitability of this yeast for use in sequential inoculation with S. cerevisiae S0-4 for the production of an American IPA-style beer and the main volatile compounds produced during fermentation were evaluated. The results show significant differences in the glycerol, isoamyl alcohol, and isoamyl acetate contents in beer obtained by sequential inoculum of M. pulcherrima 62 with S. cerevisiae S0-4 compared to beer obtained using S. cerevisiae S0-4 as a single starter. Therefore, these preliminary data support the candidacy of M. pulcherrima 62 as a new starter in the brewing process.

19 April 2023 in Processes
Verified
Journal Article
Open access
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MRMassimo Di Renzo
Massimo Di Renzo
FLFrancesco Letizia*
Francesco Letizia*
CMCatello Di Martino
Catello Di Martino
JKJulian Karaulli
Julian Karaulli
RKRenata Kongoli
Renata Kongoli
Massimo IorizzoMassimo Iorizzo
Massimo Iorizzo
The growing sensitivity toward sustainability is being demonstrated by an increase in sales of natural wines. Natural wines are obtained using exclusively native vines, indigenous yeasts, absence of additives, irregular temperature control during fermentation, and smaller quantities of sulfites even compared to organic wines. In this work, natural wines were obtained from Fiano grape, a historical cultivar of Irpinia (Campania, Italy). The main objective of this study was to compare the chemical and sensory characteristics of natural wines produced using different vessels (10 HL): Test A: stainless steel; Test B: earthenware amphora; Test C: mulberry wood barrel; and Test D: cherry wood barrel without the use of starter yeasts and chemical additives, including sulfites. Our results show a greater concentration of higher alcohols and esters in wines obtained in amphora and wooden barrels. The results of this work reveal that the type of container influences the composition of wine to an important extent. In addition, the Fiano wines obtained have a distinctive sensory profile also due to the ancestral winemaking process used, which did not involve the use of starter yeasts or technological and chemical adjuvants.

24 November 2022 in Processes
Verified
Journal Article
Open access
PDF file
BTBruno Testa
Bruno Testa
FCFrancesca Coppola
Francesca Coppola
FLFrancesco Letizia*
Francesco Letizia*
GAGianluca Albanese
Gianluca Albanese
JKJulian Karaulli
Julian Karaulli
Massimo IorizzoMassimo Iorizzo
Massimo Iorizzo
Craft breweries tend to use special raw materials and also special ingredients (spices, herbs, fruits) to typify beers, but the metabolic activities of yeasts play a primary role in defining the sensory characteristics of this beverage. Saccharomyces cerevisiae and Saccharomyces pastorianus are yeast species usually used for ale and lager beer production. The selection and use of new yeast starters with peculiar technological and enzymatic characteristics could represent the key point for the production of beers with good and distinctive organoleptic properties. In this study, the fermentative performance of S. cerevisiae 41CM yeast isolated from the vineyard environment for ale and lager craft beer production on a laboratory scale was evaluated. The commercial yeast S. cerevisiae Fermentis S-04 and S. pastorianus Weihenstephan 34/70 were used as reference strains. S. cerevisiae 41CM showed fermentative kinetics similar to commercial starters, both in lager (12 °C) and ale (20 °C) brewing. In all beers brewed, the largest percentage of volatile compounds synthesized during the fermentation were alcohols, followed by esters, terpenes, and aldehydes. In particular, S. cerevisiae 41CM starter contributed a higher relative percentage of esters in the ale beer than that detected in the lager beer, without ever synthesizing unwanted volatile compounds.

14 January 2026 in Fermentation
Verified
Journal Article
Open access
PDF file
JKJulian Karaulli
Julian Karaulli
NXNertil Xhaferaj
Nertil Xhaferaj
BTBruno Testa
Bruno Testa
Rosaria CozzolinoRosaria Cozzolino
Rosaria Cozzolino
Cristina MatarazzoCristina Matarazzo
Cristina Matarazzo
Massimo IorizzoMassimo Iorizzo
Massimo Iorizzo
Recent studies have shown that the use of non-Saccharomyces yeasts, either alone or in co-fermentation with Saccharomyces cerevisiae, can enhance the development of specialty beers with distinctive compositional characteristics. This study aimed to evaluate the main compositional and sensory differences between American Pale Ale (APA) beers produced using the commercial strain S. cerevisiae US-05 as a single starter (Test 1), and those produced through sequential inoculation with Metschnikowia pulcherrima 62 followed by S. cerevisiae US-05 (Test 2). Analyses focused on key chemical parameters and volatile compounds at the end of primary fermentation (F1) and after 20 days of refermentation at 20 °C (F2). After F1, Test 2 samples showed higher concentrations of glycerol and higher alcohols (isoamyl alcohol, benzeneethanol) and lower concentrations of esters (isoamyl acetate, ethyl hexanoate, ethyl octanoate) compared to Test 1. After F2, the differences in higher alcohol content became less significant, whereas ester concentrations, particularly ethyl acetate and ethyl octanoate, were significantly higher in Test 2. Sensory evaluation revealed that beers from Test 2 exhibited more pronounced floral and fruity notes and achieved higher overall scores in the panel assessment. These findings indicate that sequential inoculation with M. pulcherrima 62 followed by S. cerevisiae enhances both the chemical complexity and sensory appeal of APA beers, highlighting the strain’s potential as a valuable tool for developing specialty beers with unique aromatic profiles.

19 June 2026 in Preprints.org
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Preprint
Open access
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JKJulian Karaulli
Julian Karaulli
OKOnejda Kyçyk
Onejda Kyçyk
FLFatbardha Lamçe
Fatbardha Lamçe
MRMamica Ruci
Mamica Ruci
NXNertil Xhaferaj
Nertil Xhaferaj
Massimo IorizzoMassimo Iorizzo
Massimo Iorizzo
Water composition is a key factor influencing brewing performance and beer quality due to its impact on mash chemistry, fermentation kinetics, and yeast metabolism. This study evaluated the effect of four Albanian spring waters (Bogova, Germenji, Selita, and Lajthiza), each with distinct mineral compositions, on the fermentation behaviour and physicochemical characteristics of Pale Ale beer produced under standardised brewing conditions. All beers were brewed using the same malt formulation, hopping regime, yeast strain, and fermentation parameters, with water source as the sole experimental variable. The beer worts showed only moderate differences in pH, colour, extract, and density, while alcoholic fermentation proceeded efficiently in all treatments and was completed within seven days. The final beers exhibited alcohol contents within the expected range for Pale Ale beers, while more pronounced differences were observed in acidity-related parameters and secondary metabolites. In particular, volatile acidity, glycerol, acetaldehyde, and organic acid concentrations varied significantly among treatments. Beers produced with Selita and Lajthiza waters showed higher volatile acidity and acetaldehyde levels, whereas Germenji water promoted increased glycerol production and lower acetaldehyde concentration. Correlation analysis and principal component analysis confirmed significant associations between brewing water mineralisation and fermentation-derived compounds. Calcium, magnesium, conductivity, and hardness were positively associated with glycerol production, while bicarbonate concentration influenced final beer pH and acidity development. Overall, the results demonstrate that Albanian spring waters are suitable for Pale Ale production and confirm that water mineral composition significantly affects yeast metabolism and the chemical profile of the final beers. These findings highlight the importance of water chemistry as a technological factor in craft beer production and may contribute to the valorisation of Albanian spring waters for geographically distinctive brewing applications.

15 August 2026 in Fermentation
Verified
Journal Article
Open access
PDF file
MRMamica Ruci
Mamica Ruci
RKRenata Kongoli
Renata Kongoli
Rosaria CozzolinoRosaria Cozzolino
Rosaria Cozzolino
Cristina MatarazzoCristina Matarazzo
Cristina Matarazzo
BTBruno Testa
Bruno Testa
Massimo IorizzoMassimo Iorizzo
Massimo Iorizzo
The growing demand for clean-label and low-sulphite wines has increased interest in alternative preservation strategies capable of reducing sulphur dioxide (SO2) usage while maintaining wine quality and stability. In this study, the effectiveness of Vitis vinifera leaf extract as a natural alternative to sulphur dioxide was evaluated in High Hydrostatic Pressure (HHP)-treated Fiano wines. Three experimental wines were produced: CW (control wine), SW (sulphited wine), and LW (leaf-extract wine). Following alcoholic fermentation, all wines were subjected to HHP treatment (600 MPa for 5 min) and stored at 4 °C for 60 days. Physicochemical parameters, volatile organic compounds (VOCs), and sensory characteristics were evaluated immediately after alcoholic fermentation and after HHP treatment followed by refrigerated storage. Compared with the control wine, LW exhibited approximately 20% higher total polyphenol concentrations, whereas SW showed the greatest preservation of fermentation-derived esters. HHP treatment induced only moderate changes in the volatile fraction, confirming the suitability of this non-thermal technology for wine stabilization. LW wines were characterized by higher abundances of terpene-related compounds, C6 alcohols, medium-chain fatty acids, and phenolic-associated volatiles, resulting in more pronounced floral, balsamic, herbaceous, and vegetal sensory attributes. Principal Component Analysis (PCA) explained 79.0% of the total VOC variability and clearly differentiated LW wines from CW and SW according to their volatile profiles, while sensory analysis confirmed the development of a distinctive aromatic identity associated with grapevine leaf extract. Overall, the results indicate that the combined application of V. vinifera leaf extract and HHP represents a promising strategy for the partial replacement of sulphur dioxide in white winemaking. This integrated approach contributes to wine stabilization while promoting the valorization of grapevine leaves as a sustainable winery by-product within a circular economy framework.