Abstract
BackgroundCheese ripening is a complex, time consuming and expensive process, which involves the generation of precursors from carbohydrates, proteins and fats and their subsequent conversion into a wide range of compounds responsible for the flavour and texture of the cheese. This study aims to investigate production of cheese aroma compounds outside the cheese matrix that could be applied for instance as food supplements in dairy or non-dairy products.ResultsIn this study, aroma formation by a dairy Lactococcus lactis was analysed as a function of the growth medium [milk, hydrolysed micellar casein isolate (MCI) and chemically defined medium (CDM)] and the cultivation conditions (batch culture, retentostat culture and a milli-cheese model system). In the retentostat cultures, the nutrient supply was severely restricted resulting in low growth rates (~ 0.001 h−1), thereby mimicking cheese ripening conditions in which nutrients are scarce and bacteria hardly grow. In total 82 volatile organic compounds were produced by the bacteria. Despite the use of a chemically defined medium, retentostat cultures had the biggest qualitative overlap in aroma production with the milli-cheese model system (36 out of 54 compounds). In the retentostat cultures, 52 known cheese compounds were produced and several important cheese aroma compounds and/or compounds with a buttery or cheese-like aroma increased in retentostat cultures compared to batch cultures and milli-cheeses, such as esters, methyl ketones, diketones and unsaturated ketones. In cultures on CDM and MCI, free fatty acids and their corresponding degradation products were underrepresented compared to what was found in the milli-cheeses. Addition of a mixture of free fatty acids to CDM and MCI could help to enhance flavour formation in these media, thereby even better resembling flavour formation in cheese.ConclusionsThis study demonstrates that retentostat cultivation is the preferred method to produce cheese flavours outside the cheese matrix by mimicking the slow growth of bacteria during cheese ripening.
Highlights
Cheese ripening is a complex, time consuming and expensive process, which involves the generation of precursors from carbohydrates, proteins and fats and their subsequent conversion into a wide range of compounds responsible for the flavour and texture of the cheese
Lactococcus lactis FM03-V1 was grown in retentostat and batch cultures on a chemically defined medium (CDM) to determine the effect of the cultivation method, imposing slow and fast growth respectively, on the formation of aroma compounds
Aroma formation was analysed in batch cultures using three different media [CDM, hydrolysed micellar casein isolate (MCI) and full fat milk] and in a milli-cheese model system, which could indicate the origin of the compounds and show which methods best resemble aroma formation during cheese ripening
Summary
Cheese ripening is a complex, time consuming and expensive process, which involves the generation of precursors from carbohydrates, proteins and fats and their subsequent conversion into a wide range of compounds responsible for the flavour and texture of the cheese. Most of the methods to accelerate cheese ripening focus on enhancing proteolysis and lipolysis by for instance ripening at elevated temperatures, the addition of van Mastrigt et al Microb Cell Fact (2018) 17:104 enzymes (e.g. lipases, proteinases and peptidases), microencapsulation of enzymes, using attenuated starter cultures, culture adjuncts and genetically modified cultures Each of these methods have their advantages and disadvantages that are extensively reviewed by Azarnia et al [4], but have in common that they mainly enhance precursor formation and not their subsequent conversion into aroma compounds which requires intact cells with functional metabolic pathways [2]. Such studies could help to optimise or steer aroma formation by lactic acid bacteria in such a way that these aroma compounds can be applied as food supplements in dairy or dairy-like products
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
