Nutrient enrichment of dairy curd by incorporation of whole and ruptured microalgal cells (Nannochloropsis salina)

This work investigated incorporation of Nannochloropsis salina into renneted dairy gels and curd. Whole and ruptured microalgal cells did not impair kappa-casein macropeptide cleavage by the rennet enzyme. However, insoluble components of ruptured cells impeded gelation, presumably by hindering interactions between renneted casein micelles. Confocal imaging showed that whole cells were retained and homogenously distributed within the protein network of the gels and cooked curd, whereas ruptured algae formed large aggregates that altered the protein matrix. Eicosapentaenoic acid (EPA) in the whole microalgal cells was incorporated within the curds, with considerably less EPA retained for ruptured cells. Soluble algal debris did not impair gelation, however EPA wasn't retained in the curd. The study demonstrates that nutrient enrichment of renneted dairy products is possible by incorporating whole microalgal cells to displace milk fat with protein and the beneficial long-chain omega-3 fatty acid EPA. Future research into the optimisation of product organoleptic properties is required.

Automated summary

This study investigated the incorporation of Nannochloropsis salina into renneted dairy gels and curd. The presence of whole and ruptured microalgal cells did not affect the cleavage of kappa-casein macropeptide by the rennet enzyme. However, the insoluble components of ruptured cells hindered gelation by interfering with the interactions between renneted casein micelles. Confocal imaging revealed that whole cells were evenly distributed in the protein network of the gels and cooked curd, whereas ruptured algae formed large aggregates that altered the protein matrix. The study also found that the beneficial omega-3 fatty acid EPA was incorporated into the curds when whole microalgal cells were used, but only a small amount of EPA was retained when ruptured cells were used. Soluble algal debris did not affect gelation, but EPA was not retained in the curd.