This study addressed the effects of chitosan-based nanoparticles on microbiological quality, colour, polyphenol oxidase (PPO) and peroxidase (POD) and firmness of fresh-cut 'Gala' apple slices during storage at 5°C for 10 days. The treatments carried out were as follows: (i) slices pulverised with 110-nm chitosan nanoparticles, (ii) slices pulverised with 300-nm chitosan nanoparticles, (iii) 2 g L À1 chitosan dissolved in 2% citric acid and (iv) noncoated samples. There was an increase in chroma and a proportional decrease in hue angle and lightness. Browning of the slices coated with conventional chitosan and control was slightly intense than those coated with chitosan nanoparticles of 110 and 300 nm. The PPO and PDO activities increased with time for all samples, with irrelevant difference among the treatments. Flesh firmness did not change for any treatment and period. Coatings with chitosan nanoparticles of 110 nm showed higher antimicrobial activity against moulds and yeasts, and mesophilic and psychrotrophic bacteria than the other treatments. No Salmonella, and total and faecal coliforms were detected. This investigation supports the potential use of chitosan nanoparticles as edible coatings in controlling microbial activity in fresh-cut apples.

This paper reports the antibacterial effect and physico-chemical characterization of films containing silver nanoparticles for use as food packaging. Two masterbatches (named PEN and PEC) con- taining silver nanoparticles embedded in distinct carriers (silica and titanium dioxide) were mixed with low-density polyethylene (LDPE) in different compositions and extruded to produce plain films. These films were characterized by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Differential Scanning Calorimetry (DSC), Thermogravimetric analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR). The morphology of the films showed the formation of agglomerates of nanoparticles in both PEN and PEC composites. X-ray analyses confirmed the presence of SiO2 in PEN samples and TiO2 in PEC samples. Thermal analyses indicated an increase in thermal stability of the PEC compositions. The antimicrobial efficacy was determined by applying the test strain for Escherichia coli and Staphylococcus aureus, according to the Japanese Industrial Standard Method (JIS Z 2801:2000). The films analyzed showed antimicrobial properties against the tested microorganisms, presenting better activity against the S. aureus than E. Coli. These findings suggest that LDPE films with silver nanoparticles are promising to provide a significant contribution to the quality and safety of packaged food.

No abstract

The ever-growing environmental concern arising from the unrestricted exploitation of fossil sources for the massive production of non-biodegradable materials encourages research on alternative renewable resources. We herein pave the route for the production of biodegradable biocomposites made up of carrot minimal processing waste (CMPW) by optimizing its combination with hydroxypropyl methylcellulose (HPMC) and high-pressure microfluidized cellulose fibers, which played ligand and mechanical reinforcement roles, respectively. Ternary mixture designs established mathematical models aimed at structure-composition-property correlations, allowing their mechanical performances to be innovatively predicted without the need for further experiments. The optimized formulation comprised 33 wt.% CPMW and led to biodegradable biocomposites featuring ca. 30 MPa of tensile strength, ca. 3% elongation at break, and ca. 2 GPa of Young's modulus, properties which are suitable for food packaging applications. Finally, the film-forming protocol was successfully scaled-up through a continuous casting approach, allowing the production of 1.56 m 2 of biodegradable biocomposite in each hour. While scaling up did not affect film's barrier to moisture, it did impair its mechanical behavior.

No abstract

No abstract

Coatings are generally applied to fruit as microemulsions, but nanoemulsions are still experimental. ‘Nova’ mandarins (Citrus reticulata) were coated with shellac or carnauba (Copernica cerifera) microemulsions or an experimental carnauba nanoemulsion; these were compared with an uncoated control during storage for 7 days at 20 °C. Coatings were also tested on ‘Unique’ tangors (C. reticulata × C. sinensis) stored for 14 days at 10 °C followed by a simulated marketing period of 7 days at 20 °C. Fruit quality evaluations included weight loss, gloss, soluble solids (SS), titratable acidity (TA), pH, SS/TA ratio, internal CO2, O2, fruit juice ethanol, and other aroma volatile content. Sensory visual shine and tangerine (C. reticulata) flavor rank tests after storage were conducted, followed by an off-flavor rating. The carnauba waxes resulted in less weight loss compared with the uncoated control and shellac coating during both experiments. There were no differences in gloss measurements of ‘Nova’ mandarins; however, shellac-coated fruit ranked highest for shine in a sensory test. For ‘Unique’ tangors, initially, shellac showed the highest gloss (shine) measurement; however, at the end of storage, the nanoemulsion exhibited the highest gloss, although it was not different from that of the microemulsion. Similarly, after storage, the nanoemulsion ranked highest for visual shine, although it was not different from that of the microemulsion. There were only minor differences in SS, TA, pH, and SS/TA among treatments. The internal CO2 gas concentration and juice ethanol content generally increased and internal O2 decreased during storage. The highest levels of CO2 and ethanol were found for the shellac treatment, as was the lowest O2, indicating anaerobic respiration. There were only minor differences among the other coating treatments; however, they were only sometimes different from those of the control, which generally had the highest O2, lowest CO2, and lowest ethanol. Shellac and the carnauba microemulsion also altered the volatile profile more than the control and the nanoemulsion did, especially for ‘Unique’ tangors. For ‘Unique’ tangors, the control and nanoemulsion ranked highest for tangerine flavor and had the least off-flavor at the end of storage. Among the coatings tested, the carnauba emulsions demonstrated less water loss, imparted more sustainable gloss, and caused less ethanol production than shellac, with the nanoemulsion exhibiting higher gloss measurements, less modifications of the atmosphere and volatile profile, and, consequently, better flavor compared with the microemulsion.

In this study, dehydrated strawberries have been proposed as probiotic carriers.Strawberries were cut into halves, incorporated with probiotic Bacillus coagulans BC4 by two alternative methods (impregnation and alginate coating) and submitted to two alternative drying methods (freeze drying -FD -and oven drying -OD). Six treatments were carried out, namely: FD and OD (no probiotic), I-FD, I-OD, C-FD, and C-OD (Iand C-meaning impregnation and coating respectively). While the probiotic incorporation method affected a few properties of the resulting products (mainly the probiotic viability on processing), the drying methods resulted in remarkable differences. The freeze-dried strawberry halves presented higher retention of chemical (ascorbic acid and anthocyanin contents) and physical properties (shape, color, and firmness) as well as a better acceptance and higher probiotic viability, resulting in higher probiotic release into the small intestine. The I-FD treatment resulted in the highest probiotic viability after processing and through a 6-month storage (neat 8 log cfu.g -1 ).