The effects of ozone,ultrasound and coating with shellac and lysozyme–chitosan on fresh egg during storage at ambient temperature – part 1: interior quality changes

The objective of this research was to investigate and compare the effect of different treatments including gaseous ozone (6-ppm/4-min), ultrasound (450 W/4 min) and coating of shellac, lysozyme–chitosan (L-C) on fresh eggs internal quality during storage for six weeks at ambient temperature. The internal quality attributes such as weight loss (WL), albumen viscosity, Haugh unit (HU), yolk index, total soluble solids, albumen and yolk's pH were monitored. Control groups had the worst HU (50.04), WL (8.35%), albumen pH (9.27) and viscosity (7.72 mPa·s) values after storage. The best interior qualities were obtained by shellac coating [HU (72.37), WL (1.37) and viscosity (30.10 mPa·s)] and sonication (albumen pH: 8.22). Thus, the shellac-coated eggs maintained all the internal quality parameters at the highest values, while the ozone and ultrasound only helped to keep the internal quality and enhance the shelf life of eggs.     

The effects of ozone,ultrasound and coating with shellac and lysozyme–chitosan on fresh egg during storage at ambient temperature. Part II: microbial quality,eggshell breaking strength and FT-NIR spectral analysis

This research aims to investigate and compare the effect of different treatments, including gaseous ozone (6-ppm/4-min), ultrasound (450 W/4-min), and coatings of shellac and lysozyme–chitosan (L–C), on fresh eggs during the storage for six weeks at ambient temperature. The internal quality analysis was performed in Part I. In Part II, the bacterial qualities, Fourier transform near-infrared (FT-NIR) spectral image and eggshell breaking strength were monitored. Ozone and ultrasound helped to maintain bacterial quality, but had an adverse effect on shell strength. Coated eggs had the highest value of strength (shellac: 3.63 ± 0.54 kgf; L–C: 3.56 ± 0.54 kgf) and ultrasound-treated eggs had the lowest strength (3.13 ± 0.78 kgf) in egg top. FT-NIR measurement showed that all treatments resulted in a decrease in absorption bands throughout storage. Overall, among the treatments investigated, the coatings were the best for enhancing shelf life with higher strength in eggshell breakage, while the ozone and ultrasound only helped to keep the microbial quality and enhance the shelf life.     

Quinoa protein–chitosan–sunflower oil edible film: Mechanical,barrier and structural properties

Quinoa protein extracts (Q) were prepared and alkalised at pH 8 and 12 (Q-8 and Q-12). Qs were mixed with chitosan (CH) to form Q/CH mixtures. The optimal proportion of the mixtures was determined by the formation of coacervates. All the films were obtained by solution casting. From the optimal Q/CH mixture and the addition of three different concentrations of sunflower oil (SO) 2.9, 3.8 and 4.7 g/100 mL, and the optimal proportion of SO g/100 mL was selected based on the mechanical and barrier properties of the films. The CH, Q/CH and Q/CH/SO optimal blend films were characterised by FTIR, X-ray diffraction, and SEM. The physicochemical properties of the films were also evaluated. The 0.1 Q-8/CH blend was selected due to its high degree of interaction between the quinoa proteins and CH. The optimum concentration of SO used in the Q-8/CH/SO film was 2.9 g/100 mL. The addition of SO to the film improved the water-vapour permeability (WVP) as a result of hydrophobic interactions and the presence of clusters of hydrophobic masses on the surfaces of these films but reduced the film’s tensile strength and oxygen permeability due to the formation of micropores and microfractures detected by SEM.     

Quality changes during storage of cooked and sliced meat products measured with PTR-MS and HS-GC–MS

The changes in the VOC composition of industrially produced saveloy were measured with Proton-Transfer-Reaction Mass-Spectrometry (PTR-MS) and HeadSpace Gas chromatography–mass spectrometry (HS-GC–MS) during a six weeks storage period. A decrease in the volatile organic compounds contributing to the fresh aroma of saveloy was the main change observed with both PTR-MS and HS-GC–MS. Samples of four other types of cooked and sliced meat product were measured with PTR-MS in the middle and at the end of the four week shelf-life period. These measurements showed an increase in m/z 69, 71, 87 and 89 for the pork loin and in m/z 61 for the herbal saveloy samples. These ions were assigned to the microbial spoilage markers: acetic acid, 2- and 3-methylbutanol, 2- and 3-methylbutanal, diacetyl and acetoin. Overall, this study shows that PTR-MS has potential for quality control of cooked and sliced meat products.     

Impact of β-glucan on debittering,bioaccessibility and storage stability of skim milk fortified with shrimp oil nanoliposomes

Shrimp oil was encapsulated in nanoliposomes and fortified into skim milk. Shrimp oil nanoliposomes (SONL) were thermodynamically stable when added into skim milk at 10 mL 100 mL⁻¹. Mild bitterness in fortified skim milk caused by the SONL was masked by adding β-glucan at various levels (0.05–0.2 g 100 mL⁻¹). With the addition of SONL, fortified skim milk appeared more reddish in colour due to the presence of astaxanthin. Addition of β-glucan resulted in the increase in viscosity of the fortified milk by forming network of junction zones. During the storage of skim milk fortified with SONL and 0.1 g 100 mL⁻¹ β-glucan at 4 °C for 15 days, no major quality changes took place. Simulated in vitro digestion studies revealed that 45.41 g 100 g⁻¹ eicosapentaenoic acid (EPA) and 48.86 g 100 g⁻¹ docosahexaenoic acid (DHA) from shrimp oil were bioaccessible for absorption in the gut after digestion.     

Use of ultrasounds in the food industry–Methods and effects on quality,safety, and organoleptic characteristics of foods: A review

The use of ultrasounds has recently gained significant interest in the food industry mainly due to the new trends of consumers toward functional foods. Offering several advantages, this form of energy can be applied for the improvement of qualitative characteristics of high-quality foods as well as for assuring safety of a vast variety of foodstuffs, and at the same time minimizing any negative effects of the sensory characteristics of foods. Furthermore, the non-destructive nature of this technology offers several opportunities for the compositional analysis of foods. However, further research is required for the improvement of related techniques and the reduction of application costs in order to render this technology efficient for industrial use. This review paper covers the main applications of ultrasounds as well as several advantages of the use of the technology in combination with conventional techniques. The effects of ultrasounds on the characteristics, microbial safety, and quality of several foods are also detailed     

Micro/nano emulsion delivery systems: Effects of potato protein/chitosan complex on the stability,oxidizability, digestibility and β - carotene release characteristics of the emulsion

The stability, antioxidant activity, digestibility and β - carotene sustained - release mechanism of Pickering emulsion stabilized by potato protein/chitosan (PP/CS) complex were investigated. The results exhibited that the isoelectric point of PP increased from 4.30 to 6.50 and 7.00 after adding 0.2% and 0.4% CS to improve its surface hydrophilicity, leading to a uniform dispersion of PP. Simultaneously, the average particle size of the emulsion stabilized by the PP showed a decrease from 5102.50 nm to 784.90 and 1268.50 nm and zeta - potential of the emulsion stabilized by the PP exhibited an increase from 40.63 to 48.50 and 53.73 mV after adding 0.2% and 0.4% CS to improve the stability of the emulsion. In addition, the emulsion stabilized by the PP/CS complex was found to have a smaller storage modulus (G′), loss modulus(G″), apparent viscosity and better physical stability, which was less affected by storage time, temperature and salt ion concentration. Moreover, the emulsion stabilized by the PP/CS complex exhibited better oxidation resistance. Furthermore, the emulsion stabilized by the PP/CS complex showed good anti-digestibility and slowed the sustained release rate of β - carotene. These results will provide a theoretical basis for the application of a novel food emulsifier PP/CS complex in nano - colloid delivery system.     

Conventional freezing plus high pressure–low temperature treatment: Physical properties,microbial quality and storage stability of beef meat

Meat high-hydrostatic pressure treatment causes severe decolouration, preventing its commercialisation due to consumer rejection. Novel procedures involving product freezing plus low-temperature pressure processing are here investigated. Room temperature (20 °C) pressurisation (650 MPa/10 min) and air blast freezing (−30 °C) are compared to air blast freezing plus high pressure at subzero temperature (−35 °C) in terms of drip loss, expressible moisture, shear force, colour, microbial quality and storage stability of fresh and salt-added beef samples (Longissimus dorsi muscle). The latter treatment induced solid water transitions among ice phases. Fresh beef high pressure treatment (650 MPa/20 °C/10 min) increased significantly expressible moisture while it decreased in pressurised (650 MPa/−35 °C/10 min) frozen beef. Salt addition reduced high pressure-induced water loss. Treatments studied did not change fresh or salt-added samples shear force. Frozen beef pressurised at low temperature showed L, a and b values after thawing close to fresh samples. However, these samples in frozen state, presented chromatic parameters similar to unfrozen beef pressurised at room temperature. Apparently, freezing protects meat against pressure colour deterioration, fresh colour being recovered after thawing. High pressure processing (20 °C or −35 °C) was very effective reducing aerobic total (2-log₁₀ cycles) and lactic acid bacteria counts (2.4-log₁₀ cycles), in fresh and salt-added samples. Frozen + pressurised beef stored at −18 °C during 45 days recovered its original colour after thawing, similarly to just-treated samples while their counts remain below detection limits during storage.     

Loadings of lycopene in emulsion and sodium alginate–K-carrageenan composite systems: Preparation,characterization, bioaccessibility,and kinetics

This research aims to prepare capsules emulsion using gallic acid (GA), dextran (DEX), bovine serum albumin (BSA), sodium alginate, and K-carrageenan (K-Car) as the biological delivery system of lycopene. The stability and bioaccessibility of lycopene were further improved through encapsulation of covalent complex of sodium alginate and K-Car. The molecular weight distribution and secondary structure of the conjugates were analyzed by sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE) and Fourier transform infrared spectroscopy (FTIR). The storage stability of the emulsion stabilized by conjugates was measured with Turbiscan stability index (TSI) and fluctuation of the particle size. The TSI value of ternary conjugates was 18.7 (37℃) with particle sizes ranging from 208 to 319 nm. Then, the changes of three-dimensional reticulate structures and physical properties of sodium alginate-K were analyzed by scanning electron microscopy (SEM) and TPA. The thermal stability of the sodium alginate–K-Car composite systems was increased compared with sodium alginate. The bioaccessibility of lycopene was significantly improved under the dual embedding of BSA–DEX–GA conjugate emulsion and sodium alginate–K-Car composite systems.     

Effect of Eryngium caeruleum essential oil on microbial and sensory quality of minced fish and fate of Listeria monocytogenes during the storage at 4°C

The present study investigated in vitro antimicrobial activity of Eryngium caeruleum essential oil (EEO) against five foodborne pathogenic bacteria based on microdilution and disk diffusion methods. Moreover, its effects on specific spoilage microorganisms, inoculated Listeria monocytogenes, and its sensory changes in minced fish were evaluated during 12 days of storage at refrigeration temperature. The results showed that Staphylococcus aureus and Escherichia coli were the most sensitive and the most resistant bacteria with a minimum inhibitory concentration of 0.125 and 1 mg/ml, as well as inhibition zones of 15.66 and 11.66 mm, respectively. Regarding the antimicrobial effect of EEO on the microbial profile and inoculated L. monocytogenes, treating with 0.4% EEO caused a significant decrease in the studied microorganisms when compared to the control group (p < 0.05). In addition, considering the sensory evaluation, the best scores were observed for the samples treated with 0.2% and 0.4% EEO. However, none of the groups obtained acceptable scores until the final day of storage except for the color attribute. In general, sensory evaluation and its correlation with microbial counting indicated that the treatment with 0.4% EEO was able to preserve the microbial quality of the minced fish at refrigeration temperature without any undesirable sensory effects.     

Study of the functionality of selected hydrocolloids and their blends with κ-carrageenan on storage quality of vanilla ice cream

In the present paper, the functionality of hydrocolloids related to the rheological, physical and sensory characteristics of ice cream mixes and frozen ice cream was studied. Carboxylmethylcellulose, guar gum, sodium alginate and xanthan gum were used as primary stabilizing agents, whereas κ-carrageenan as secondary. The hydrocolloid concentrations were 0.1 and 0.2% and the primary to secondary ratio was 9:1. The ice cream samples were stored under quiescent frozen conditions. Samples were taken after 4, 8 and 16 weeks of storage and examined for the functionality of the stabilizing systems.The addition of hydrocolloids significantly reinforced the shear thinning behavior, particularly in the case of sodium alginate, xanthan gum, and κ-carrageenan which was attributed to gelation phenomena. Sodium alginate attained the better stabilizing effect improving textural quality and acceptance of ice creams even after 16 weeks of storage, whereas the presence of κ-carrageenan found to be a crucial factor for the cryoprotection. Xanthan gum was also evaluated as an effective stabilizing agent, indicating that gelling hydrocolloids may remarkably amend ice cream shelf life.Moreover, principal components and cluster analysis of instrumental and sensory data furnished important information for the correlation of objective and sensory properties and discrimination of stabilizing systems based on quality criteria.     

Characterization and antibacterial property of Kapok fibers treated with chitosan/AgCl–TiO2 colloid

The aim of this research is to investigate the antibacterial activity of Kapok fibers modified with AgCl/TiO₂ and Chitosan colloid. A very simple, single-step (pad-dry-cure) method was used for the application of AgCl/TiO₂ and Chitosan colloid on kapok fibers, the chemicals used are easily available. Different blend ratios of chitosan and AgCl/TiO₂ colloid were applied to the bleached kapok fibers and antibacterial properties were assayed against gram positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The treated kapok fibers were characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). It was observed that the bacterial growth was significantly reduced in the samples which had a higher concentration of chitosan and AgCl/TiO₂ colloid. However, a significant reduction in bacterial growth with the use of this colloid was observed.     

Development of pectin–eugenol emulsion coatings for inhibition of Listeria on webbed-rind melons: a comparative study with fig and citrus pectins

The objective of this study was to employ pectin-based antimicrobial coatings for inhibition of Listeria on surfaces of whole webbed-rind melons that cause frequent outbreaks of listeriosis. For this purpose, emulsion-based coatings were developed using citrus pectin (CPEC) or pectin extracted from processing wastes of sun-dried figs (FPEC) and eugenol (EUG). The emulsions of FPEC and CPEC with EUG (droplet size range: 1.99–11.22 µm) were highly stable for minimum 10 days at 10 °C. The FPEC-EUG films showed higher flexibility and degree of wettability than CPEC-EUG films. In contrast, CPEC-EUG films had a higher gas barrier performance against oxygen at 50% relative humidity than FPEC-EUG films. The zone inhibition tests showed that FPEC-EUG films are more effective against Listeria innocua than CPEC-EUG films. However, FPEC and CPEC coatings with 2% EUG caused 2.2 and 2.7 decimal inactivation of Listeria on Galia melons within 1 week, respectively. The pectin coatings with EUG could reduce the risk of listeriosis from webbed-rind melons.     

Freezing-induced changes in goat cheese: Effect of freezing rate,storage and freeze–thaw cycles

This study compared the effect of various freezing set-ups [freezing in the walk-in freezer (WF), blast freezing and liquid nitrogen freezing (LNF)] on the textural properties of goat cheeses. The influences of freeze–thaw cycles (1, 3 and 5) and storage time (1, 7 and 14 days) at 4°C on the hardness and visual appearance were investigated. The results showed that freezing damaged the cheese structure, particularly for WF. Frozen samples were not suitable for 4°C storage. Freeze–thaw cycles further damaged the texture of both cheese logs and crumbles, resulting in increased dryness. The development of the dry structure was faster for the LNF-treated sample.     

Formation and characterisation of food protein–polysaccharide thermal complex particles: effects of pH,temperature and polysaccharide type

The objective of this study was to prepare and characterise the thermal complex particles (TCPs) based on heating food grade protein–polysaccharide electrostatic complexes. The soybean protein isolate (SPI), cationic polysaccharide (chitosan, CS) and anionic polysaccharide (carboxymethyl cellulose, CMC) were used. Turbidity, particle size, ζ-potential and morphology of TCPs were measured. The results showed that SPI-CS and SPI-CMC soluble complexes were obtained at specific pHs and kept at high electrostatic repulsive force. The particle size and polydispersity index of stable SPI-CS (pH 4.55/80 °C) and SPI-CMC (pH 6.15/95 °C) TCPs were 286.6 nm/0.282 and 171.5 nm/0.298, respectively. We inferred that the re-assembly of SPI after thermal denaturation resulted in the formation of TCPs. The pH and ionic strength sensitivity tests indicated that the TCPs with different properties can be controlled by pH, temperature and polysaccharide type during heating. These TCPs could be used to encapsulate food functional components which were thermal insensitive.