# Characterization of Tiroler Bergkäse PDO cheese: A multimethodological approach

## TL;DR

This study used multiple methods to compare Tiroler Bergkäse PDO cheese with similar cheeses, highlighting differences in microbial and chemical profiles.

## Contribution

The study introduces a multimethodological approach to distinguish PDO and non-PDO alpine cheeses using microbial and chemical analysis.

## Key findings

- PDO Bergkäse has high levels of L. delbrueckii and free amino acids due to traditional production and longer ripening.
- Stilfser type cheese differs significantly in bacterial composition, amino acid content, and volatile profile from Bergkäse types.
- Multivariate analysis confirmed significant differences between PDO and non-PDO Bergkäse cheeses.

## Abstract

Tiroler Bergkäse PDO is a traditional Austrian hard cheese from Tyrol, a product of great regional significance. This study aimed to describe Tiroler Bergkäse PDO by comparing it with Bergkäse without PDO from Tyrol and a Stilfser type cheese from South Tyrol. To account for variability, three cheese wheels from three production days were analyzed for each cheese. Multimethodological characterization included quantitative Polymerase Chain Reaction, Ion Exchange Chromatography, and Headspace-Solid Phase Microextraction/Gas Chromatography-Mass Spectrometry. The characterization Tiroler Bergkäse PDO should impart potentially unique features. Multivariate analysis of the bacterial composition, free amino acid content, and volatile fraction revealed differences between all cheeses (α = 0.05). A triangle test confirmed significant differences, with more pronounced differences between the Bergkäse type cheeses and the Stilfser type cheese. The Stilfser type showed distinct differences in bacterial composition, amino acid content, and volatile profile, making it less similar to the Bergkäse type cheeses. Multivariate analysis also revealed differences between the PDO and non-PDO Bergkäse which is characterized by high levels of L. delbrueckii due to its starter culture, and a high free amino acid content from longer ripening, alongside elevated levels of hexanal and acetoin. In contrast, Bergkäse without PDO shows high levels of 2,3-butanediol and 2-nonanone, alongside high levels of L. mesenteroides, L. lactis subsp. lactis, and L. lactis subsp. cremoris. It was possible to distinguish between Tiroler Bergkäse PDO from non-PDO cheeses by microbial, amino acid, and volatile profiles and support the use of advanced methods to characterize regional foods.

•Multimethodology to characterize alpine cheeses and distinguish between PDO and non-PDO.•qPCR, IEC, HS-SPME/GC–MS, and multivariate analysis used.•Microbial, amino acid, and volatile profiles confirmed differences between cheeses.•Multimethodological analysis linked microbial diversity to PDO cheese quality.•PDO Bergkäse's traits were shaped by traditional production methods.

Multimethodology to characterize alpine cheeses and distinguish between PDO and non-PDO.

qPCR, IEC, HS-SPME/GC–MS, and multivariate analysis used.

Microbial, amino acid, and volatile profiles confirmed differences between cheeses.

Multimethodological analysis linked microbial diversity to PDO cheese quality.

PDO Bergkäse's traits were shaped by traditional production methods.