Characteristics of Unripened Cow Milk Curd Cheese Enriched with Raspberry (Rubus idaeus), Blueberry (Vaccinium myrtillus) and Elderberry (Sambucus nigra) Industry By-Products

The aim of this study was to apply raspberry (Ras), blueberry (Blu) and elderberry (Eld) industry by-products (BIB) for unripened cow milk curd cheese (U-CC) enrichment. Firstly, antimicrobial properties of the BIBs were tested, and the effects of the immobilization in agar technology on BIB properties were evaluated. Further, non-immobilized ((NI)) and agar-immobilized ((AI)) BIBs were applied for U-CC enrichment, and their influence on U-CC parameters were analyzed. It was established that the tested BIBs possess desirable antimicrobial (raspberry BIB inhibited 7 out of 10 tested pathogens) and antioxidant activities (the highest total phenolic compounds (TPC) content was displayed by (NI) elderberry BIB 143.6 mg GAE/100 g). The addition of BIBs to U-CC increased TPC content and DPPH- (2,2-diphenyl-1-picrylhydrazyl)-radical scavenging activity of the U-CC (the highest TPC content was found in C-Ra-NI 184.5 mg/100 g, and strong positive correlation between TPC and DPPH- of the U-CC was found, r = 0.658). The predominant fatty acid group in U-CC was saturated fatty acids (SFA); however, the lowest content of SFA was unfolded in C-Eld(AI) samples (in comparison with C, on average, by 1.6 times lower). The highest biogenic amine content was attained in C-Eld(AI) (104.1 mg/kg). In total, 43 volatile compounds (VC) were identified in U-CC, and, in all cases, a broader spectrum of VCs was observed in U-CC enriched with BIBs. After 10 days of storage, the highest enterobacteria number was in C-Blu(NI) (1.88 log(10) CFU/g). All U-CC showed similar overall acceptability (on average, 8.34 points); however, the highest intensity of the emotion happy was expressed by testing C-Eld(NI). Finally, the BIBs are prospective ingredients for U-CC enrichment in a sustainable manner and improved nutritional traits.

Automated summary

The aim of this study was to utilize raspberry, blueberry, and elderberry industry by-products for unripened cow milk curd cheese enrichment. The BIBs showed desirable antimicrobial and antioxidant activities. Adding BIBs to U-CC increased the content of total phenolic compounds and the DPPH-radical scavenging activity. The BIB-enriched U-CC also exhibited changes in fatty acid composition, biogenic amine content, volatile compounds, and enterobacteria number. Overall acceptability of U-CC with BIBs was similar, but emotional response varied.