Effect of different colored filters on photooxidation in pasteurized milk

The effect of different colored filters and atmospheres on photooxidation and quality in milk was studied. Pasteurized bovine milk (3.9% fat) was packed in 2 different atmospheres (air and N₂) and exposed to light for 20 h at 4°C under 8 transparent filters with different light transmission properties. The following transparent, noncolored, and colored filters based on polyethylene terephthalate (PET) were used: noncolored (PET), noncolored with 2 different UV-block regions, yellow, green, amber, orange, and red. Control samples were stored in darkness and in a carton. Sensory evaluation showed off flavors significantly increased in milk stored under all filters compared with the control samples. Variation in atmosphere resulted in significant differences in formation of rancid flavor in milk stored under different filters. Milk samples stored in N₂ underwent the most sensory deterioration under orange and red filters, whereas milk samples stored in air were most deteriorated under noncolored filters. According to the oxidation compounds measured by gas chromatography, milk samples stored under noncolored and orange filters were highly oxidized, whereas red, green, and amber filters offered better protection against photooxidation. Fluorescence spectroscopy was used to examine the degradation of photosensitizers (riboflavin, protoporphyrin, and chlorophyllic compounds) in the milk samples. Degradation of protoporphyrin and chlorophyllic compounds in N₂ correlated well with sensory properties related to photooxidation (R² = 0.75-0.95). The study indicates that protoporphyrin and chlorophyllic compounds were effective photosensitizers in milk. To avoid photooxidation in milk, it is therefore important to protect it against light from the UV spectrum as well as light from the entire visible region.     

Effects of UV-B irradiation on the levels of anthocyanin,rutin and radical scavenging activity of buckwheat sprouts

The effects of various light compositions on the levels of anthocyanin, rutin and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity in buckwheat (Fagopyrum esculentum Moench) sprouts were evaluated. Dark-grown 6-day-old buckwheat sprouts were irradiated with different sources of visible and ultraviolet (UV) light. Particularly, we examined the effect of UV-B at wavelengths of 260–320 nm, 280–320 nm, and 300–320 nm on the production of flavonoid compounds, using multiple fluorescent lights and cylinders that filter out certain portions of the UV-B. The results showed that irradiation with UV-B > 300 nm increased the levels of anthocyanin and rutin, as well as the DPPH radical scavenging activity. When sprouts were irradiated with UV-B light at wavelengths of 260–300 nm, yellowing or withering occurred within 24 h of irradiation, indicating that wavelengths in this range are detrimental to the growth of buckwheat sprouts.     

An optoelectronic instrument for the determination of sulphite in beverages

The paper describes an optoelectronic device that has been designed and developed to measure the sulphite concentration in beverages for quality evaluation. A selective and sensitive method for determination of sulphite is based on the reaction with pararosaniline acid bleached dye and formaldehyde solution, which gives violet colored complex having absorption maxima at 560 nm. Lambert–Beer’s law is obeyed in the concentration range up to 25 μg/ml (25 ppm) of test solution within an accuracy of ±0.05μg/ml (0.05 ppm). The instrument involves the use of high intensity green light emitting diode (LED) of wavelength 565 nm as light source. BPW21 photodiode having the relative spectral sensitivity above 90% in the range of 500–600 nm has been used as a detector, for the determination of sulphite concentration.     

Effect of light on growth,intracellular and extracellular pigment production by five pigment-producing filamentous fungi in synthetic medium

The competence of the living creatures to sense and respond to light is well known. The effect of darkness and different color light quality on biomass, extracellular and intracellular pigment yield of five potent pigment producers Monascus purpureus, Isaria farinosa, Emericella nidulans, Fusarium verticillioides and Penicillium purpurogenum, with different color shades such as red, pink, reddish brown and yellow, were investigated. Incubation in total darkness increased the biomass, extracellular and intracellular pigment production in all the fungi. Extracellular red pigment produced by M. purpureus resulted maximum in darkness 36.75 ± 2.1 OD and minimum in white unscreened light 5.90 ± 1.1 OD. Similarly, intracellular red pigment produced by M. purpureus resulted maximum in darkness 18.27 ± 0.9 OD/g and minimum in yellow light 8.03 ± 0.6 OD/g of substrate. The maximum biomass production was also noticed in darkness 2.51 g/L and minimum in yellow light 0.5 g/L of dry weight. In contrast, growth of fungi in green and yellow wavelengths resulted in low biomass and pigment yield. It was found that darkness, (red 780–622 nm, blue 492–455 nm) and white light influenced pigment and biomass yield.     

Properties of a protein-based film from round scad (Decapterus maruadsi) as affected by muscle types and washing

The effects of muscle types and washing on the properties of a protein-based film from round scad (Decapterus maruadsi) mince were investigated. Washing resulted in an increase in the protein content with a coincidental decrease in the fat content of mince, especially from whole muscle and dark muscle. Among all types of muscle (ordinary, dark and whole muscle), the ordinary muscle rendered the film with the highest tensile strength (TS) (p < 0.05). TS of films from washed mince was greater than that of films prepared from unwashed mince for the same type of muscle used (p < 0.05). Nevertheless, the water vapour permeability (WVP) of films from unwashed mince was higher than that of films prepared from washed mince (p < 0.05). Films from washed mince had higher solubility but lower protein solubility than those from unwashed mince (p < 0.05). Regardless of washing, films from ordinary muscle showed the highest L^∗-value (p < 0.05). However, films prepared from dark muscle were more yellowish than those prepared from other muscles, as evidenced by the greater b^∗-value. Films from round scad mince and washed mince had excellent barrier properties to UV light at the wavelength of 200–280 nm. Generally, films from round scad mince had a lower preventive effect on visible light transmission than had those from unwashed mince. Among films from all muscles, those prepared from dark muscle exhibited the highest barrier to visible light transmission (p < 0.05). Therefore, the properties of films from round scad meat were governed by muscle type as well as by washing.     

Effects of partial hydrolysis and plasticizer content on the properties of film from cuttlefish (Sepia pharaonis) skin gelatin

Properties of film from cuttlefish (Sepia pharaonis) ventral skin gelatin with different degree of hydrolysis (DH: 0.40, 0.80 and 1.20%) added with glycerol as plasticizer at various levels (10, 15 and 20%, based on protein) were investigated. Films prepared from gelatin with all DH had the lower tensile strength (TS) and elongation at break (EAB) but higher water vapor permeability (WVP), compared with the control film (without hydrolysis) (p < 0.05). At the same glycerol content, both TS and EAB decreased, while WVP increased (p < 0.05) with increasing %DH. At the same DH, TS generally decreased as glycerol content increased (p < 0.05), however glycerol content had no effect on EAB when gelatins with 0.80 and 1.20% DH were used (p > 0.05). DH and glycerol content had no marked impact on color and the difference in color (ΔE^∗) of resulting films. Electrophoretic study revealed that degradation of gelatin and their corresponding films was more pronounced with increased %DH, resulting in the lower mechanical properties of films. Based on FTIR spectra, with the increasing %DH as well as glycerol content, higher amplitudes for amide-A and amide-B peaks were observed, compared with film from gelatin without hydrolysis (control film) due to the increased –NH₂ group caused by hydrolysis and the lower interaction of –NH₂ group in the presence of higher glycerol. Thermo-gravimetric analysis indicated that film prepared from gelatin with 1.20% DH exhibited the higher heat susceptibility and weight loss in the temperature range of 50–600 °C, compared with control film. Thus, both chain length of gelatin and glycerol content directly affected the properties of cuttlefish skin gelatin films.     

The use of front face fluorescence spectroscopy to classify the botanical origin of honey samples produced in Switzerland

This study reports the use of front face fluorescence spectroscopy as a tool for the classification of honey samples from Switzerland according to their botanical origins. Honey (n = 62) fluorescence spectra from seven floral origins, namely, acacia, alpine rose, chestnut, rape, honeydew, alpine polyfloral and lowland polyfloral were scanned after excitation set at 250 nm (emission: 280–480 nm), 290 nm (emission: 305–500 nm) and 373 nm (emission: 380–600 nm) and emission set at 450 nm (excitation: 290–440 nm). The first 10 principal components (PCs) of the principal component analysis (PCA) extracted from each data set were gathered together into one matrix and analysed by factorial discriminant analysis (FDA). Correct classification of 100% and 90% was observed for the calibration and the validation samples, respectively. The seven honey types were well discriminated indicating that the molecular environment and, for consequent, the physico-chemical properties of the investigated honeys were different. The obtained results showed that front face fluorescence spectroscopy might be a suitable and alternative technique to classify honey samples according to their botanical origins.     

Short communication: Suitability of fluorescence spectroscopy for characterization of commercial milk of different composition and origin

Thirteen milk brands comprising 76 pasteurized and UHT milk samples of various compositions (whole, reduced fat, skimmed, low lactose, and high protein) were obtained from local supermarkets, and milk samples manufactured in various countries were discriminated using front-face fluorescence spectroscopy (FFFS) coupled with chemometric tools. The emission spectra of Maillard reaction products and riboflavin (MRP/RF; 400 to 600 nm) and tryptophan (300 to 400 nm) were recorded using FFFS, and the excitation wavelengths were set at 360 nm for MRP/RF and 290 nm for tryptophan. Principal component analysis (PCA) was applied to analyze the normalized spectra. The PCA of spectral information from MRP/RF discriminated the milk samples originating in different countries, and PCA of spectral information from tryptophan discriminated the samples according to composition. The fluorescence spectral data were compared with liquid chromatography-mass spectrometry results for the glycation extent of the milk samples, and a positive association (R² = 0.84) was found between the degree of glycation of α-lactalbumin and the MRP/RF spectral data. This study demonstrates the ability and sensitivity of FFFS to rapidly discriminate and classify commercial milk with various compositions and processing conditions.     

不同波段的光照对无菌牛奶中光敏剂降解的影响

在油脂光照氧化过程中起催化作用的光敏剂在不同可见光照波段下有着不同的吸收特性。光敏剂对光照的吸收量越大,光敏剂降解得越迅速。研究不同可见光光照波段对无菌牛奶中光敏剂核黄素与原卟啉降解的影响,确定出这两种光敏剂降解最为迅速的光照波段。实验结果表明核黄素在400~500nm、原卟啉在500~600nm光照波段下降解迅速。因此,牛奶在这两个光照波段下氧化变质可能更为迅速。      

Properties of film from cuttlefish (Sepia pharaonis) skin gelatin incorporated with cinnamon,clove and star anise extracts

Properties of film from cuttlefish (Sepia pharaonis) ventral skin gelatin without and with partial hydrolysis (1.2% degree of hydrolysis) incorporated with 1% ethanolic extract of cinnamon (CME), clove (CLE) and star anise (SAE) were determined. Films with different herb extracts (without and with oxidation) had higher tensile strength (TS) but lower elongation at break (EAB), compared with the control film (without addition of herb extracts) (p < 0.05). Lower water vapor permeability (WVP) and L^∗-value but higher b^∗- and ΔE^∗-values were observed when the extracts were incorporated (p < 0.05). Electrophoretic study revealed that cross-linking was pronounced in films containing different herb extracts. Oxidized extracts yielded films with higher TS and WVP than those without oxidized herb extracts (p < 0.05). Generally, similar properties were noticeable for films from gelatin with and without partial hydrolysis. Nevertheless, higher mechanical properties were obtained for the latter. FTIR spectra indicated that protein–polyphenol interactions were involved in the film. Thermo-gravimetric analysis revealed that films incorporated with SAE or SAE with oxidation (OSAE) exhibited lower heat susceptibility and weight loss in the temperature range of 50–600 °C, compared with control film. Films with SAE and OSAE had smoother surface for gelatin without hydrolysis; however, coarser surface was observed in film from gelatin with partial hydrolysis. Thus, the incorporation of different herb extracts directly affected the properties of film from cuttlefish skin gelatin with and without hydrolysis.     

Comparison of the properties of multi-composite fish gelatin films with that of mammalian gelatin films

Four types of films viz. gelatin, gelatin–MMT, gelatin–chitosan and gelatin–MMT–chitosan prepared from redsnapper and grouper bone gelatin were compared with the mammalian gelatin films, for their mechanical and barrier properties. Grouper gelatin films had higher tensile strength (TS) and Young’s modulus (YM), but lower elongation at break (EAB) than redsnapper films. Incorporation of MMT and chitosan improved the TS (p < 0.05) of the films. Water solubilities were lower (p < 0.05) in films incorporated with chitosan compared to simple gelatin film. Protein solubilities were lower in gelatin–MMT films, irrespective of the type of solvent used. The water vapour transmission rates (WVTR) of fish and mammalian gelatin films were similar, but addition of MMT had reduced WVTR (p < 0.05). SEM micrographs depicted smoother surface for gelatin–MMT and gelatin–MMT–chitosan films. Thus, composite fish gelatin films made with MMT and chitosan could be the good natural biodegradable films due to their better mechanical and barrier properties.     

Microstructure and optical properties of sodium caseinate films containing oleic acid–beeswax mixtures

The effect of internal and surface structure of films obtained from sodium caseinate (NaCas), containing glycerol and lipid mixtures of oleic acid (OA) and beeswax (BW) (1:0.3:0.5 protein:glycerol:lipid ratio) on optical properties (gloss and transparency) was studied. Gloss was measured at different angles of the incident light (20, 60 and 85°) using a gloss meter, and transparency was evaluated through Kubelka–Munt coefficients obtained from the film reflection spectra (400–700 nm). Film structure was analyzed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Control films (without lipid) exhibited the greatest transparency and gloss whereas lipid imparts opacity and loss of gloss to the film, especially as beeswax increased in the lipid mixture, due to the formation of greatest lipid aggregates in the internal and surface parts of the film. Good correlation was established among gloss, transparency and surface roughness parameters of the films.     

Properties and antioxidant activity of fish skin gelatin film incorporated with citrus essential oils

Properties of protein-based film from fish skin gelatin incorporated with different citrus essential oils, including bergamot, kaffir lime, lemon and lime (50% based on protein) in the presence of 20% and 30% glycerol were investigated. Films containing 20% glycerol had higher tensile strength (TS) but lower elongation at break (EAB), compared with those prepared with 30% glycerol, regardless of essential oils incorporated (p < 0.05). Films incorporated with essential oils, especially from lime, at both glycerol levels showed the lower TS but higher EAB than the control films (without incorporated essential oil) (p < 0.05). Water vapour permeability (WVP) of films containing essential oils was lower than that of control films for both glycerol levels (p < 0.05). Films with essential oils had varying ΔE^* (total colour difference), where the highest value was observed in that added with bergamot essential oil (p < 0.05). Higher glycerol content increased EAB and WVP but decreased TS of films. Fourier transforms infrared (FTIR) spectra indicated that films added with essential oils exhibited higher hydrophobicity with higher amplitude at wavenumber of 2874–2926 cm⁻¹ and 1731–1742 cm⁻¹ than control film. Film incorporated with essential oils exhibited slightly lower thermal degradation resistance, compared to the control film. Varying effect of essential oil on thermal degradation temperature and weight loss was noticeable, but all films prepared using 20% glycerol had higher thermal degradation temperature with lower weight loss, compared with those containing 30% glycerol. Films added with all types of essential oils had rough cross-section, compared with control films, irrespective of glycerol levels. However, smooth surface was observed in all film samples. Film incorporated with lemon essential oil showed the highest ABTS radical scavenging activity and ferric reducing antioxidant power (FRAP) (p < 0.05), while the other films had lower activity. Thus, the incorporation of different essential oils and glycerol levels directly affected the properties of gelatin-based film from fish skin.     

Effect of high pressure processing on rheological and structural properties of milk–gelatin mixtures

There is an increasing demand to tailor the functional properties of mixed biopolymer systems that find application in dairy food products. The effect of static high pressure processing (HPP), up to 600 MPa for 15 min at room temperature, on milk–gelatin mixtures with different solid concentrations (5%, 10%, 15% and 20% w/w milk solid and 0.6% w/w gelatin) was investigated. The viscosity remarkably increased in mixtures prepared with high milk solid concentration (15% and 20% w/w) following HPP at 300 MPa, whereas HPP at 600 MPa caused a decline in viscosity. This was due to ruptured aggregates and phase separation as confirmed by confocal laser scanning microscopy. Molecular bonding of the milk–gelatin mixtures due to HPP was shown by Fourier-transform infrared spectra, particularly within the regions of 1610–1690 and 1480–1575 cm⁻¹, which reflect the vibrational bands of amide I and amide II, respectively.     

Development and characterization of composite edible films based on sodium alginate and pectin

The objective of this study was to characterize physical properties including thickness, colour, water vapour sorption kinetics and isotherms, water vapour permeability, tensile strength, elongation at break, and microstructure of composite films prepared by casting sodium alginate and low methoxy pectin at proportions of: 100–0%, 75–25%, 50–50%, 25–75%, and 0–100%. Combination of both polysaccharides gave continuous, homogenous and transparent films. All of analyzed films reached their state of equilibrium within the 24 h of adsorption time. Water sorption isotherms for all films had a sigmoidal shape and were not influenced by the film composition. Sorption kinetics and isotherms indicated hydrophilic character of investigated films. Statistically significant (p < 0.001) correlations were found between colour, water vapour permeability, tensile strength, elongation at break, and chemical composition (alginate and pectin) of composite films. A different internal arrangement was observed as a function of film composition.     

Preparation and properties of dialdehyde carboxymethyl cellulose crosslinked gelatin edible films

Glycerol-plasticized gelatin edible films with a new kind of dialdehyde polysaccharide, dialdehyde carboxymethyl cellulose (DCMC) as crosslinking agent are successful prepared using casting techniques. The mechanical properties, thermal stability, light barrier properties, swelling behavior as well as water vapor permeability (WVP) of the gelatin-DCMC films are investigated. The results indicate that the addition of DCMC causes tensile strength (TS) and thermal stability to increase and elongation at break (EB) to decrease, suggesting the occurrence of crosslinking between gelatin and DCMC. The light barrier measurements present high values of transparency at 280 nm and low values of transparency at 600 nm of the gelatin-DCMC films, indicating that gelatin-DCMC films are very transparent (lower in transparency value) while they have excellent barrier properties against UV light. Moreover, the values of transparency at 280 nm increase with the increased DCMC and glycerol content, suggesting the potential preventive effect of gelatin-DCMC films on the retardation of product oxidation induced by UV light. Furthermore, the addition of DCMC can greatly decrease the water vapor permeability (WVP) and equilibrium swelling ratio (ESR) down to values about 1.5 × 10⁻¹⁰ g m/m² s Pa and 150%, revealing the potential of DCMC in reducing the water sensitivity of gelatin-based films. In common for hygroscopic plasticizer in edible films, the addition of glycerol gives increase of EB and WVP and decrease of thermal stabilities and ESR of the gelatin-DCMC films.     

Influences of degree of hydrolysis and molecular weight of poly(vinyl alcohol) (PVA) on properties of fish myofibrillar protein/PVA blend films

Biodegradable blend films based on fish myofibrillar protein (FMP) and poly(vinyl alcohol) (PVA) were prepared and characterized. PVA with different degrees of hydrolysis (DH) and molecular weights (MW) had the impact on properties of FMP/PVA (1:1, w/w) blend film. The blend films with higher MW of PVA were more tensile resistant, as indicated by the greater tensile strength (TS) and elongation at break (EAB), while the films with PVA of lower DH were more flexible. The blend film with PVA-BP26 (DH: 86–98% mol; MW: 124,000–130,000 g/mol) exhibited the greatest tensile performance and the lowest water vapor permeability (p < 0.05), compared with other films. SEM and FTIR results revealed that FMP and PVA were compatible and their intermolecular interaction was enhanced, providing the blend film with desirable properties. Therefore, incorporation of PVA with appropriated DH and MW could improve the properties of the FMP-based film.     

Effect of heat treatment of film-forming solution on the properties of film from cuttlefish (Sepia pharaonis) skin gelatin

Effects of heat treatment at different temperatures (40–90 °C) of film-forming solution (FFS) containing 3% gelatin from cuttlefish (Sepia pharaonis) ventral skin and 25% glycerol (based on protein) on properties and molecular characteristics of resulting films were investigated. The film prepared from FFS heated at 60 and 70 °C showed the highest tensile strength (TS) with the highest melting transition temperature (T_max) (p < 0.05). Nevertheless, film from FFS heated at 90 °C had the highest elongation at break (EAB) with the highest glass transition temperature (T_g) (p < 0.05). With increasing heating temperatures, water vapor permeability (WVP) of films decreased (p < 0.05), but no differences in L*-value and transparency value were observed (p > 0.05). Based on FTIR spectra, the lower formation of hydrogen bonding was found in film prepared from FFS with heat treatment. Electrophoretic study revealed that degradation of gelatin was more pronounced in FFS and resulting film when heat treatment was conducted at temperature above 70 °C. Thus, heat treatment of FFS directly affected the properties of resulting films.     

Thermodynamic analysis of the thermal stability of sulphonamides in milk using liquid chromatography tandem mass spectrometry detection

The present study investigates the kinetics of the degradation of eight sulphonamides in skimmed milk when heated at 60, 70, 80, 90 and 100 °C using an LC–MS/MS methodology. To determine the thermal stability of these compounds, the first-order kinetic model was applied and the activation energies, half-lives and degradation percentages were calculated. Application of kinetic equations to the different heat treatments used in dairy processing indicates that sulphonamides are very stable during pasteurisation (63 °C; 30 min and 72 °C; 15 s) as well as UHT sterilisation (140 °C; 4 s). In contrast, the calculations performed with the kinetic model estimated losses in concentrations between 6.5% (sulfadimethoxine) and 85.1% (sulfamethazine) for the sterilisation at 120 °C for 20 min. The existence of thermodynamic compensation was also tested for sulphonamide degradation. Results show that enthalpy and entropy values displayed a good linear relationship, and thermodynamically we can establish that the thermal degradation of sulphonamides in skimmed milk exhibits enthalpy–entropy compensation.     

Feasibility of Vis/NIR spectroscopy for detection of flaws in hazelnut kernels

The feasibility of Vis/NIR spectroscopy for detection of flaws in hazelnut kernels (Corylus avellana L. cv. Tonda Gentile Romana) is demonstrated. Feature datasets comprising raw absorbance values, raw absorbance ratios (Abs[λ₁]:Abs[λ₂]) and differences (Abs[λ₁] − Abs[λ₂]) for all possible pairs of wavelengths from 306.5 nm to 1710.9 nm were extracted from the spectra for use in an iterative LDA routine. For each dataset, several spectral pretreatments were tested. Each group of features selected was subjected to Partial Least Squares Discriminant Analysis (PLS-DA), Receiver Operating Characteristics (ROCs) analysis, and evaluation of performance through the Area Under ROC Curve. The best result (5.4% false negative, 5.0% false positive, 5.2% total error) was obtained using a Savitzky–Golay second derivative on the dataset of raw absorbance differences. The optimal features were Abs[564 nm]–Abs[600 nm], Abs[1223 nm]–Abs[1338 nm] and Abs[1283 nm]–Abs[1338 nm]. The results indicate the feasibility of a rapid, online detection system.