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- Melanin: production from cheese bacteria, chemical characterization, and biological activitiesPublication . Ferraz, Ana Rita Simões; Pacheco, Rita; Vaz, Pedro D.; Pintado, Cristina Santos; Ascensão, Lia; Serralheiro, Maria LuísaPigments are compounds of importance to several industries, for instance, the food industry, where they can be used as additives, color intensifiers, and antioxidants. As the current trend around the world is shifting to the use of eco-friendly commodities, demand for natural dyes is increasing. Melanins are pigments that are produced by several microorganisms. Pseudomonas putida ESACB 191, isolated from goat cheese rind, was described as a brown pigment producer. This strain produces a brown pigment via the synthetic Müeller-Hinton Broth. This brown compound was extracted, purified, analyzed by FTIR and mass spectrometry, and identified as eumelanin. The maximum productivity was 1.57 mg/L/h. The bioactivity of eumelanin was evaluated as the capacity for scavenging free radicals (antioxidant activity), EC50 74.0 ± 0.2 µg/mL, and as an acetylcholinesterase inhibitor, with IC50 575 ± 4 µg/mL. This bacterial eumelanin did not show cytotoxicity towards A375, HeLa Kyoto, HepG2, or Caco2 cell lines. The effect of melanin on cholesterol absorption and drug interaction was evaluated in order to understand the interaction of melanin present in the cheese rind when ingested by consumers. However, it had no effect either on cholesterol absorption through an intestinal simulated barrier formed by the Caco2 cell line or with the drug ezetimibe.
- WPI active edible coatings to prevent cheese color defectsPublication . Ferraz, Ana Rita Simões; Anjos, O.; Serralheiro, Maria Luísa; Pintado, Cristina SantosCheese is a type of food that has been used over time as a way of preserving milk. It is a popular food because of its excellent versability and palatability. All around the world a huge variety of cheeses, flavors, and shapes can be found. This food product depends on the culture and available resources of each region. In 2021, global cheese production amounted to about 21.86 million metric tons 1. The European Union was by far the top producer of cheese worldwide, with a production volume of around 10.35 million metric tons of cheese that year.
- Novel, edible melanin-protein-based bioactive films for cheeses: antimicrobial, mechanical and chemical characteristicsPublication . Ferraz, Ana Rita Simões; Goulão, Manuela; Espírito Santo, Christophe; Anjos, O.; Serralheiro, Maria Luísa; Pintado, Cristina SantosThe cheese rind is the natural food packaging of cheese and is subject to a wide range of external factors that compromise the appearance of the cheese, including color defects caused by spoilage microorganisms. First, eight films based on whey protein isolate (WPI) coatings were studied, of which IS3CA (WPI 5% + sorbitol 3% + citric acid 3%) was selected for presenting better properties. From the IS3CA film, novel films containing melanin M1 (74 g/mL) and M2 (500 g/mL) were developed and applied to cheese under proof-of-concept and industrial conditions. After 40 days of maturation, M2 presented the lowest microorganism count for all the microbial parameters analyzed. The cheese with M2 showed the lowest lightness, which indicates that it is the darkest cheese due to the melanin concentration. It was found that the mechanical and colorimetric properties are the ones that contribute the most to the distinction of the M2 film in cheese from the others. Using FTIR-ATR, it was possible to distinguish the rinds of M2 cheeses because they contained the highest concentrations of melanin. Thus, this study shows that the film with M2 showed the best mechanical, chemical and antimicrobial properties for application in cheese.
- A global review of cheese colour: microbial discolouration and innovation opportunitiesPublication . Ferraz, Ana Rita Simões; Pintado, Cristina Santos; Serralheiro, Maria LuísaCheese is a biologically active food product, characterised by its colour, texture, and taste. Due to its rich matrix of fats and proteins, as well as the fact that the cheese’s surface acts as its own packaging, the cheese becomes more susceptible to contamination by microorganisms during the ripening process, particularly bacteria and fungi. The ripening of cheese involves several biochemical reactions, with the proteolytic activity of the cheese microbiota being particularly significant. Proteolysis results in the presence of free amino acids, which are precursors to various metabolic mechanisms that can cause discolouration (blue, pink, and brown) on the cheese rind. Surface defects in cheese have been documented in the literature for many years. Sporadic inconsistencies in cheese appearance can lead to product degradation and economic losses for producers. Over the past few decades, various defects have been reported in different types of cheese worldwide. This issue also presents opportunities for innovation and development in edible and bioactive coatings to prevent the appearance of colour defects. Therefore, this review provides a comprehensive analysis of cheese colour globally, identifying defects caused by microorganisms. It also explores strategies and innovation opportunities in the cheese industry to enhance the value of the final product.
- Spectroscopic insights into prodigiosin pigment production by Serratia marcescensPublication . Ferraz, Ana Rita Simões; Fernandes, Mariana; Goulão, Manuela; Pintado, Cristina Santos; Anjos, O.The appearance of cheese can be influenced by the intentional use of dyes such as paprika that color its rind, particularly in smear-ripened cheeses. In addition to this intentional addition, some microorganisms naturally present in cheeses can produce pigments that lead to color defects that negatively impact consumer acceptance and economic profitability. Serratia marcescens can produce a red pigment known as prodigiosin (Di Salvo, 2023). Prodigiosin is the most prominent secondary metabolite in the group of prodiginin compounds, with cycloprodigiosine, metacycloprodigiosine, undecylprodigiosin, prodigiosin R1, and streptorubin B (Stankovic et al., 2014). It was evaluated the prodigiosin production in two bacterial cultures Serratia marcescens ESACB 596 and Serratia marcescens ESACB 734, sourced from the Microbial Culture Collection of the Microbiology Laboratory of Polytechnic Institute of Castelo Branco, Portugal, with the aim to determine the optimal conditions to produce pink pigment. To achieve this, experiments were performed in three culture media (Luria Broth (LB), Nutritive Broth (NB) and Peptone Glycerol Phosphate (PGP), at two pH levels (7.5 and 8.0) and two different temperatures (22 °C and 28 °C).