Fresh cheese made from concentrated milk: Tailoring the calcium content of milk retentates by means of microfiltration to modulate the bitter taste

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The manufacture of fermented fresh cheese varieties like quarg or cottage cheese involves two main steps: fermentation, where milk is gelled, and concentration, which separates the curd-whey mixture into acid whey and fresh cheese with a specific protein content. However, valorizing acid whey is challenging due to complex processing. To eliminate acid whey production, efforts were made to fully concentrate milk before fermentation using ultrafiltration. Unfortunately, the resulting fresh cheeses exhibited sensory defects, particularly a bitter taste, attributed to high calcium ion content. This thesis hypothesizes that reducing calcium levels before fermentation can decrease bitterness in fresh cheese made from microfiltered retentates. A target calcium content of < 1800 mg/kg was established to mitigate bitterness, as seen in cream cheese. The approach involved developing a process to remove calcium from casein micelles via microfiltration, producing skim milk retentates with low calcium and avoiding acid whey. An experimental setup for fermenting milk retentates was proposed, alongside an instrumental method for identifying and quantifying bitter peptides in fresh cheese. A feasibility study confirmed that reducing calcium prior to fermentation significantly lowered perceived bitterness and bitter peptide content in concentrated-fermented fresh cheese, validating the hypothesis.