Novel, Edible Melanin-Protein-Based Bioactive Films for Cheeses: Antimicrobial, Mechanical and Chemical Characteristics

The 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 µg/mL) and M2 (500 µg/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.

Labdanum Resin from Cistus ladanifer L.: A Natural and Sustainable Ingredient for Skin Care Cosmetics with Relevant Cosmeceutical Bioactivities

Labdanum resin from Cistus ladanifer L. (Cistaceae) is an abundant natural resource in the Iberian Peninsula worth being explored in a sustainable manner. It is already used in the cosmetic industry; mainly by the fragrances/perfumery sector. However, given the highest market share and traditional uses, labdanum resin also has the potential to be used and valued as a cosmetic ingredient for skincare. Aiming to evaluate this potential, labdanum methanolic absolute and fractions purified by column chromatography were characterized by UPLC-DAD-ESI-MS and then evaluated for UV-protection, antioxidant, anti-elastase, anti-inflammatory, and antimicrobial activities. Labdanum absolute represented ~70% of the resin; diterpenoid and flavonoid fractions represented ~75% and 15% of the absolute, respectively. Labdane-type diterpenoids and methylated flavonoids were the main compounds in labdanum absolute and in diterpenoid and flavonoid fractions, respectively. Labdanum absolute showed a spectrophotometric sun protection factor (SPF) near 5, which is mainly due to flavonoids, as the flavonoids’ SPF was 13. Low antioxidant activity was observed, with ABTS radical scavenging being the most significant (0.142 ± 0.017, 0.379 ± 0.039 and 0.010 ± 0.003 mgTE/mgExt, for the absolute and flavonoid and terpene fractions, respectively). Anti-aging and anti-inflammatory activity are reported here for the first time, by the inhibition of elastase activity (22% and 13%, by absolute and flavonoid extract at 1 mg/mL), and by the inhibition of nitric oxide production in LPS-induced RAW 264.7 cells (84% to 98%, at 15 µg/mL extracts, flavonoid fraction the most active), respectively. Antimicrobial activity, against relevant skin and cosmetic product microorganisms, Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, and Escherichia coli, revealed that only S. aureus was susceptible to labdanum absolute (MIC: 1.2 mg/mL) and its fractions (MIC: <0.3 mg/mL). In conclusion, labdanum resin showed potential to be used in sunscreen cosmetics, anti-inflammatory skincare cosmeceuticals or medicines but has low potential as a cosmetic product preservative given the low antioxidant and low-spectrum antimicrobial activities.

Association between a case study of asymptomatic ovine listerial mastitis and the contamination of soft cheese and cheese processing environment with Listeria monocytogenes in Portugal

For 5 months, the udders of milking ewes, raw ewe's milk, cheese, and the plant and environment of a cheese manufacturer in Portugal were investigated using standard methods for the presence of Listeria spp. An association between subclinical mastitis and Listeria monocytogenes in a single lactating sheep was investigated by visual inspection of udders for signs of inflammation, application of somatic cell counts, the California mastitis test, pH measurement to milk, and culture of L. monocytogenes and Staphylococcus spp. To track the routes of contamination by L. monocytogenes, 103 isolates were characterized by molecular serotyping and amplified fragment length polymorphism, and a selection was further tested by pulsed-field gel electrophoresis. This study provides molecular and epidemiological evidence tracking the persistence of a single L. monocytogenes strain causing a subclinical udder infection without obvious inflammation in a single ewe. This infection was the likely source of contamination of raw milk that was subsequently used to produce unpasteurised milk cheese and resulted in a single strain of this bacterium colonizing the processing environment and the final cheese product.

Properties of whey protein-based films containing organic acids and nisin to control Listeria monocytogenes

Whey protein isolate and glycerol were mixed to form a matrix to incorporate antimicrobial agents and produce edible films with antimicrobial activity against Listeria monocytogenes strains isolated from cheeses. Various organic acids were used to decrease pH down to approximately 3. In a preliminary assay without nisin, the effect of each organic acid was evaluated with respect to the rheological properties of the film solutions and the inhibitory and mechanical properties of the films. Lactic, malic, and citric acids (3%, wt/vol), which were used in a subsequent study of their combined inhibitory effect with nisin (50 IU/ml), had significantly higher antilisterial activity (P < 0.05) compared with the control (2 N HCl, 3% [wt/vol], with nisin). The largest mean zone of inhibition was 4.00 +/- 0.92 mm for malic acid with nisin. Under small-amplitude oscillatory stress, the protein-glycerol-acid film solutions exhibited a predominantly viscous behavior or a weak gel behavior, with the storage modulus (G') slightly higher than the loss modulus (G"). The malic acid-based solution was the only one whose viscosity was not influenced by the addition of nisin. The addition of nisin resulted in a nonsignificant (P > 0.05) increase in the percentage of elongation at break. Results from tensile and puncture stress were variable, but in general no significant differences were found after the incorporation of nisin. The overall results support the use of malic acid with nisin to produce effective antimicrobial films to control L. monocytogenes growth.