Biopreservatives against foodborne bacteria: combined effect of nisin and nanoncapsulated curcumin and co-encapsulation of nisin and curcumin.

Nisin, a bacteriocin widely used in the food industry, and curcumin, the yellow pigment extracted from turmeric (Curcuma longa L.) stand out among the numerous natural preservatives that have antimicrobial activity. The conversion of these compounds into nanoparticles could be interesting as an alternative to improve technological aspects (such as the low water solubility of curcumin) and to evaluate how synergism could take place in the case of co-encapsulation. The main objective of the present work was to evaluate the combination of nisin (Nis) with nanoencapsulated curcumin (NCur, nanoencapsulated to promote water solubility), as well as the co-encapsulated curcumin and nisin (NCurNis), against the foodborne bacteria Staphylococcus aureus, Escherichia coli and Salmonella Typhimurium. Minimum inhibitory concentration and the minimum bactericidal concentration were evaluated for NCur and Nis, as well as their combination with the fractional inhibitory concentration assay. High effectiveness was found against S. aureus and the combination of both compounds resulted in Nis- nisin; synergism against the same microorganism. The co-encapsulation of curcumin and nisin was carried out based on the synergism tests and the characterization analyses demonstrated that a solid dispersion of the components in the PVP matrix was formed. The inhibitory effect of the curcumin and nisin co-encapsulate was improved when compared to the curcumin nanoparticles or nisin alone. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-022-05641-8.

Antibacterial efficacy of Enterococcus microencapsulated bacteriocin on Listeria monocytogenes, Listeria innocua and Listeria ivanovi.

This study focused on the microencapsulation of enterocin from Enterococcus durans (E. durans MF5) in whey powder (WP) using a spray-drying technique followed by the evaluation of how complexation can preserve the enterocin structure and antimicrobial activity against food-borne pathogens. Crude enterocin samples (1 and 5%) were microencapsulated in 10% WP. The antimicrobial activity of unencapsulated (crude) enterocin and microencapsulated enterocin was tested against the target bacteria Salmonella Typhimurium, Escherichia coli, Listeria monocytogenes, Listeria innocua, and Listeria ivanovi. The microencapsulation yields were 31.66% and 34.16% for concentrations of 1 and 5% enterocin, respectively. There was no significant difference between these concentrations. Microencapsulated enterocin was efficient for up to 12 h of cocultivation with Listeria sp., and the concentration required to inhibit the growth of target bacteria presented values of 6400 AU/mL (arbitrary unit). Microencapsulated enterocin demonstrated enhanced efficacy against Listeria species and E. coli when compared with crude enterocin (p < 0.05). Fourier transform-infrared spectroscopy and differential scanning calorimetry results confirmed the presence of enterocin in the microparticles. Scanning electron microscopy showed cell damage of the target bacteria. The results showed that complexation with WP preserved enterocin antimicrobial activity during spray-drying, indicating its potential use as a food preservative.

Chemometric evaluation of enzymatic hydrolysis in the production of fish protein hydrolysates with acetylcholinesterase inhibitory activity.

Fish protein hydrolysates (FPH) obtained from industrial processing residues are sources of bioactive peptides. The enzymatic hydrolysis process is essential in obtaining specific bioactivities such as inhibition of the enzyme acetylcholinesterase (AChE). In this study the effect of different hydrolysis conditions on the properties of FPH to inhibit the enzyme acetylcholinesterase. A chemometric evaluation, based on a central composite rotatable design and principal component analysis, was applied to select hydrolysis conditions with best yield, degree of hydrolysis and acetylcholinesterase inhibition. Experimental design results for AChE inhibition were between 10.51 and 40.45% (20, 30 and 50 mg.mL-1 of FPH), and three hydrolysis conditions were selected based on PCA evaluation. The amino acids profile, FTIR and AChE inhibition kinetics were evaluated. Results showed a mixed type of inhibition behavior and, the docking molecular analyzes suggest that the inhibition AChE occurred due to the basic amino acids, mainly by arginine.

Bioactivity screening of pinhão (Araucaria Angustifolia (Bertol.) Kuntze) seed extracts: the inhibition of cholinesterases and α-amylases, and cytotoxic and anti-inflammatory activities.

The objective of this work was to determine the potential bioactive properties of extracts from bio-residues of pinhão (Araucaria angustifolia (Bertol.) Kuntze) seeds, namely the α-amylase and cholinesterase inhibition, cytotoxicity, and anti-inflammatory properties. The pinhão extracts evaluated were obtained from cooking water (CW) and as an ethanolic extract from residual pinhão seed shells (PS). Catechin was the major compound found in both extracts. The PS extract presented higher antioxidant levels and the better inhibition of human salivary and porcine pancreatic α-amylases when compared to the CW extract. Also, based on in vivo evaluations, the PS extract did not differ significantly from acarbose when compared to a control group. The most potent inhibitor of cholinesterases was the CW extract. No cytotoxicity toward normal cells was detected, and neither extract showed anti-inflammatory activity. The PS extract presented cytotoxic activity toward non-small-cell lung, cervical, hepatocellular and breast carcinoma cell lines. Overall, the results demonstrated the potential bioactivity of extracts obtained from pinhão bio-residues.

Use of nanoencapsulated curcumin against vegetative cells and spores of Alicyclobacillus spp. in industrialized orange juice.

Pathogenic and deteriorating bacteria are a great concern to food safety. In this sense, the present study evaluated the fight against microbial contamination through the use of nanoparticles containing curcumin, in addition to analyzing the physical properties of these nanoparticles. Efficient curcumin encapsulation was determined by Fourier transform infrared spectra evaluation and differential scanning calorimetry. Transmission electron microscopy images showed irregular shaped nanoparticles with broad size distribution (20-250 nm). The antibacterial activity was considered satisfactory, since curcumin in the form of nanoparticles demonstrated antimicrobial and antibacterial activity superior to curcumin in its free form, against both pathogenic bacteria, such as Staphylococcus aureus (MIC 125 µg/mL), and deteriorates, such as Alicyclobacillus acidoterrestris (MIC 62.5 µg/mL). Since curcumin nanoparticles may be consumed as a food additive, the bioactive properties of the nanoencapsulated curcumin were also evaluated in relation to antioxidant capacity (Thiobarbituric acid reactive substances (TBARS) and oxidative hemolysis inhibition assays) and cytotoxicity against four carcinoma cell lines, as well as two non-tumor cells. As a proof of concept, nanoparticles were incorporated in orange juice, with the juice maintaining satisfactory pH, °Brix, and color stability, during three days of storage (8 °C).

Analytical validation of an ultraviolet-visible procedure for determining vitamin D3 in vitamin D3-loaded microparticles and toxigenetic studies for incorporation into food.

Vitamin D is a water-insoluble compound presented in two main forms (D2 and D3), susceptible to environmental conditions. Microencapsulation is an alternative to supplements and preserve vitamin D properties in foods. Entrapment efficiency (EE) is the main property to evaluate the encapsulation effectiveness and therefore it is of interest the study of analytical methods for the identification and quantification of this compound within the particle. This paper describes a low cost UV-Vis methodology validation to the identification and quantification of vitamin D3 in microparticles produced by hot homogenization. The method was validated following the International Conference on Harmonization (ICH) guidelines. To guarantee safe application in foodstuff, microparticles toxigenicity was evaluated with Allium cepa L. in vivo model, showing no cytotoxic nor genotoxic potential. High entrapment efficiency was obtained, the results also demonstrated that the concentration of vitamin D3 in microparticles can be safely accessed by the validated method.

Araucaria angustifolia (Bertol.) Kuntze extract as a source of phenolic compounds in TPS/PBAT active films.

There is growing interest in the development of biodegradable packaging materials containing natural antioxidant extracts. In this sense, the use of extracts obtained from agro-industrial byproducts has proved to be a sustainable alternative. In this study, Pinhão extract, a byproduct of Pinhão (Araucaria angustifolia (Bertol.) Kuntze) seed consumption, was characterized by HPLC-DAD-ESI/MSn, demonstrating the presence of eight phenolic compounds, (+)-catechin and (-)-epicatechin being the most abundant molecules. TPS/PBAT films containing Pinhão extract were produced by blown extrusion and their properties (tensile properties, thermal characteristics and microstructure) were evaluated in order to determine the effect of the presence of extracts. Results suggested that the interaction between the phenolic compounds of the extract and the polymeric matrix caused the reduction in the crystallinity degree, and an increase in the starch glass transition temperature. The presence of Araucaria angustifolia (Bertol.) Kuntze extract significantly (p < 0.05) affected the color and opacity of the film. Regarding water vapor permeation, no significant difference (p > 0.05) was detected. However, the water solubility and the contact angle with water (polar solvent) and diiodomethane (non-polar solvent) significantly changed due to the extract addition. Moreover, the Pinhão extract conferred significant antioxidant capacity to the TPS/PBAT films as determined by DPPH, suggesting that this material can be applied as an active packaging material.