DI PAOLO, MARIKA (2025) Valorization and utilization strategy of food wastes and by-products of Buffalo milk production chain - GREENBUF. [Tesi di dottorato]

Documento PDF PhD_thesis_DI_PAOLO_fedoa.pdf Visibile a [TBR] Amministratori dell'archivio Download (3MB) | Richiedi una copia

Abstract

The buffalo milk production chain is a sector characterized by significant volumes of milk, by-products, and industrial waste. This highlights both the potential for economic opportunities and the urgent need for sustainable management within the dairy industry. In line with current sustainable development policies, this thesis aimed to identify innovative methods and technologies to valorize by-products and waste generated from buffalo milk processing. The main challenge has been demonstrating the potential of dairy processing waste materials by identifying substances that can be used to produce innovative, high-quality dairy products with enhanced nutraceutical profiles. In Chapter 1, the phospholipid (PL) profile of buffalo milk and dairy by-products from the production of buffalo mozzarella (whey) and butter (buttermilk) was analyzed. The study evaluated the effects of technological processes (e.g., coagulation, homogenization, churning) and thermal treatments (low and high pasteurization). The results demonstrated that processes conducted at lower temperatures tend to better preserve PLs. Additionally, the processing methods were shown to influence the composition of phospholipids in the milk fat globule membrane (MFGM), leading to its reorganization and an increase in the PL concentration in buttermilk. Based on these findings, the study provided the foundation for developing a PL extraction protocol using selective extraction with supercritical carbon dioxide and ethanol as a co-solvent. These results provide valuable insights into the dairy industry and related applications, contributing to the valorization of buffalo dairy products. Chapter 2 explored the antimicrobial properties of cell-free supernatants (CFS) produced by selected LAB strains isolated from buffalo milk and whey. The strains were selected based on their antibiotic susceptibility and haemolytic activity. Antimicrobial activity was evaluated against reference strains of Listeria monocytogenes, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella Enteritidis and Salmonella Typhimurium. The results revealed that the CFS demonstrated antimicrobial activity against all tested bacteria, with L. monocytogenes being the most sensitive. This suggested that the antimicrobial activity is mainly due to the presence of organic acids and, in the case of seven lactic acid bacteria (LAB) strains (four isolated from buffalo milk and three isolated from buffalo whey), a possible bacteriocin-like compound. Furthermore, the genome sequencing analysis of Lactiplantibacillus plantarum (strain isolated from buffalo milk) yielded interesting results, revealing the presence of genes encoding two bacteriocin precursor peptides. These findings highlight the potential of LAB as a natural bio-preservatives, offering safe and effective solutions for improving food safety and shelf life, particularly in dairy products. To this purpose, the goal of Chapter 3 was examining the antioxidant activity of selected LAB strains isolated from buffalo whey and milk through assays including hydroxyl radical scavenging, DPPH radical scavenging, total antioxidant capacity (TAC), and ferric reducing antioxidant power (FRAP). The results indicated strain-specific antioxidative responses. LAB strains from buffalo milk displayed varying levels of resistance to oxidative stress induced by hydrogen peroxide, with certain strains maintaining survival rates above 80% at 0.7 mM H₂O₂. Additionally, CFS from strains such as Lacticaseibacillus rhamnosus and Lactiplantibacillus plantarum demonstrated superior TAC and FRAP values, highlighting their ability to chelate Cu²⁺ and Fe²⁺ ions. As for LAB strains isolated from buffalo whey, they showed enhanced ferric-reducing power compared to those from buffalo milk. These findings underscore the significance of LABs in developing functional foods, providing a natural alternative to synthetic preservatives. The selected LAB strains were identified as the most promising candidates for use as bio-preservative cultures with both antimicrobial and antioxidant properties, aimed at enhancing shelf life and health benefits. In Chapter 4, a functional homogenized buffalo ricotta was developed by incorporating three bio-protective lactic acid bacteria (LAB) strains isolated from buffalo milk and whey selected based on their safety and functional characteristics. The viable counts of LAB strains, physicochemical characteristics, and consumer acceptance of the newly formulated buffalo ricotta were evaluated to optimize the technological process in dairy industries and enhance the quality of the final product. The results showed that the buffalo ricotta maintained potential probiotic viability above the recommended threshold (10⁶ CFU/g). However, excessive acidity and bitterness developed after 15 days, reducing sensory acceptability and overall quality. Despite these challenges, this preliminary study highlights the potential of buffalo ricotta as a carrier for probiotics and underscores the need for further optimization of sensory attributes to enhance consumer acceptance. Additionally, further research is needed to evaluate the effect of LAB on oxidation indices and microbial populations. Overall, this thesis highlights the significant potential of buffalo milk and its by-products as valuable resources for both economic opportunities and sustainable practices in the dairy industry. The comprehensive analysis of buffalo milk’s phospholipid profile, the antimicrobial properties of lactic acid bacteria (LAB), and antioxidant activity demonstrates promising avenues for valorizing dairy waste and enhancing dairy product quality. Moreover, the thesis provides valuable insights for developing new functional foods to improve the microbial quality and health value of products, such as buffalo ricotta, by using natural functional compounds. The results of this thesis pave the way for further studies on the exploitation and optimization of new functional foods, with potential market applications. These findings address the needs of various industrial sectors and offer specific solutions for the sustainable transition.

Downloads

Actions (login required)

Modifica documento