Effect of various salts and pH condition on rheological properties of Salvia macrosiphon hydrocolloid solutions

The extraction of Salvia macrosiphon seed hydrocolloid was performed successfully and the optimum hydration time and temperature were found to be 30 min and 25 °C for 12% extraction yield. The effect of solution pH (3–9) and addition of NaCl (0.5–3%), CaCl₂ (0.5–3%) and Na₂HPO₄ (0.2–0.6%) on rheological properties of the hydrocolloid solutions were investigated. Rheologcal data were fitted with the Power law model with regression coefficient of greater than 0.95. Strong shear thinning behavior with the n value of less than 0.53 was recorded. All variables had significant impacts on rheological parameters. The minimum and maximum consistencies were found at pH 3 and the 9, respectively. This was explained with the presence of carboxylic groups on the biopolymer backbone as indicated by FTIR. NaCl, CaCl₂ and Na₂HPO₄ had significant effects on rheological properties. Moreover, at similar salt concentration of 0.5%, Na₂HPO₄ had the greatest and NaCl had the lowest effect.     

The influence of latitude on the concentration of vitamin D3 and 25-hydroxy-vitamin D3 in Australian red meat

There is little information on the vitamin D content of Australian red meat or on the possible influence of latitude on this content. To determine the content of vitamin D₃ and 25-hydroxy-vitamin D₃ (25OHD₃), lamb and beef were analysed from 34° S with LC–IT-MS. To investigate the possible influence of latitude on vitamin D in meat, the lean meat and fat from five cuts of beef were analysed from 17° S and 41° S. Lamb contained 0.10 μg vitamin D₃/100 g and 0.20 μg 25OHD₃/100 g lean meat, while beef contained 0.12 μg vitamin D₃ and 0.27 μg 25OHD₃/100 g (lean meat). Latitude had no effect on the vitamin D₃ (P = 0.21) or 25OHD₃ (P = 0.29) content of lean beef, but fat from cattle in the 17° S latitude group contained significantly higher (P < 0.01) concentrations of vitamin D₃ than fat from the 41° S group of cattle.     

Pasteurization of grapefruit juice using a centrifugal ultraviolet light irradiator

Studies are lacking on the nonthermal pasteurization of liquid foods using UV irradiators that centrifugally form very thin films to overcome the problem of limited penetration depth of UV. Grapefruit juice inoculated with Escherichia coli or Saccharomyces cerevisiae was processed at the following conditions: UV dose 4.8–24 mJ/cm²; treatment time 3.2 s, cylinder rotational speed 450–750 rpm, cylinder inclination angle 15–45°, outlet temperature 11 °C, and flow rate 300 ml/min, and was stored for 35 days. Appropriate dilutions of the samples were pour plated with TSA and TSA + 3% NaCl for E. coli and Sabouraud dextrose agar (SDA) and SDA + 5% NaCl for S. cerevisiae. Nonthermal UV processing at 19 mJ/cm², 450 rpm and 15° reduced E. coli in grapefruit juice by 5.1 log₁₀. A dose of 14 mJ/cm² reduced S. cerevisiae by 6.0 log₁₀. Inactivation increased linearly with increasing UV dose. The inactivations at 600 and 750 rpm were similar, and were better than at 450 rpm. The results at 30° and 45° were similar, and were better than at 15°. The occurrence of sublethal injury in either microorganism was not detected. Storing UV processed grapefruit juice at 4 and 10 °C reduced the surviving E. coli to below 1 log₁₀ cfu/ml in 14 days. Processing UV juice reduced the population of S. cerevisiae to less than 1 log₁₀ cfu/ml where it remained for 35 days during refrigerated storage. These results suggest that grapefruit juice may be pasteurized using a nonthermal UV irradiator that centrifugally forms a thin film.     

Triglycerides constituted of short and medium chain fatty acids and dicarboxylic acids in Momordica charantia, as well as capric acid,inhibit PGE2 production in RAW264.7 macrophages

This study was aimed to identify compounds in bitter gourd (Momordica charantia) ethyl acetate extract (EAE), which inhibit lipopolysaccharide-induced prostaglandin E₂ (PGE₂) production in RAW264.7 cells. Bitter gourd EAE was partitioned between n-hexane and methanol/H₂O (90/10). The hexane fraction was further separated by repeated silica gel chromatographies, and a reverse phase (RP) C18 chromatography. Fraction RP-10 showed the highest inhibition effect on PGE₂ production (Max inhibition = 96%, IC₅₀ = 2.3 μg/ml) and was identified to be triglycerides constituted of short and medium chain fatty acids by ¹H NMR, IR and H–HCOSY, and dicarboxylic acids by GC/MS. Fatty acids with 3–20 carbons were tested for the inhibitory activity, and capric acid exhibited the highest effect (Max inhibition = 99%, IC₅₀ = 6.5 μM). In conclusion, triglycerides composed of short and medium chain fatty acids and dicarboxylic acids in bitter gourd inhibit PGE₂ production, and capric acid is the most potent inhibitor among the fatty acids.     

Thermal inactivation of Yersinia enterocolitica in pork slaughter plant scald tank water

The objective of this study was to establish the time–temperature combinations required to ensure the thermal inactivation of Yersinia enterocolitica during scalding of pork carcasses. A 2 strain cocktail of Y. enterocolitica (bioserotypes 2/O:5,27 and 1A/O:6,30) was heat treated at 50, 55 and 60 °C in samples of scald tank water obtained from a commercial pork slaughter plant. Samples were removed at regular intervals and surviving cells enumerated using (i) Cefsulodin–Irgasan–Novobiocin Agar (CIN) supplemented with ampicillin and arabinose and (ii) Tryptone Soya Agar (TSA), overlaid with CIN agar with ampicillin and arabinose. The data generated was used to estimate D- and z-values and the formula D_x = log^− 1(log D₆₀ − ((t₂ − t₁)/z)) was applied to calculate thermal death time–temperature combinations from 55 to 65 °C. D₅₀, D₅₅ and D₆₀-values of 45.9, 10.6 and 2.7 min were calculated from the cell counts obtained on CIN agar, respectively. The corresponding D-values calculated from the TSA/CIN counts were 45.1, 11 and 2.5 min, respectively. The z-value was 7.8. It was concluded that a time–temperature combination of 2.7 min at 60 °C is required to achieve a 1 log reduction in Y. enterocolitica in pork scald tank water. The predicted equivalent at 65 °C was 0.6 min. This study provides data and a model to enable pork processors to identify and apply parameters to limit the risk of carcass cross-contamination with Y. enterocolitica in pork carcass scald tanks.     

Isolation and characterisation of acid-solubilised collagen from the skin of Nile tilapia (Oreochromis niloticus)

Acid-solubilised collagen (ASC) was extracted from the skin of Nile tilapia (Oreochromis niloticus) and characterisation was studied. The results indicated that the yield of ASC was 39.4% on the basis of dry weight. This ASC was rich in glycine (35.6%). The amount of imino acids, proline and hydroxyproline, in ASC was 210 residues per 1000 residues. The ultraviolet (UV) absorption spectrum of ASC showed that the distinct absorption was at 220 nm. ASC showed transition curve at maximum temperature (T_max) of 32.0 °C in 0.05 M acetic acid, about 12 °C lower than that of calf skin collagen. Maximum solubility (0.75 mg/ml) in 0.5 M acetic acid was observed at pH 3. Solubility reached the minimum at pH 7. A sharp decrease in solubility was observed in 2% (w/v) NaCl or above. Biochemical studies indicated that ASC was composed of the α1α2α3 heterotrimers.     

Effects of hydrogen peroxide and Fenton’s reagent on the properties of film from cuttlefish (Sepia pharaonis) skin gelatin

Properties of film from cuttlefish (Sepia pharaonis) ventral skin gelatin without and with partial hydrolysis (1.2% degree of hydrolysis), as influenced by H₂O₂ and Fenton’s reagent at different levels, were investigated. Films treated with H₂O₂ (0.01–0.04 M) and Fenton’s reagent [H₂O₂ (0.01–0.04 M) + FeSO₄ (0.001–0.004 M)] had higher tensile strengths (TS) but similar or lower elongations at break (EAB), compared with the control film (p < 0.05). Slight differences in water vapour permeability (WVP) were observed for all films. Films treated with Fenton’s reagent had a lower L^∗-value but higher a^∗-, b^∗- and ΔE^∗-values, while films treated with H₂O₂ had lower b^∗-values (p < 0.05), than had the control film. Cross-linking was pronounced in films treated with H₂O₂ or Fenton’s reagent and was associated with increased heat stability. Films treated with Fenton’s reagent had the lowest solubility in water (p < 0.05). However, fragmentation more likely took place when Fenton’s reagent (at a higher level) was used. Generally, similar results were noticeable between films from gelatin with and without partial hydrolysis. Thus, H₂O₂ and Fenton’s reagent directly affected the properties of film from cuttlefish skin gelatin, regardless of hydrolysis.     

Effects of light,temperature and water activity on the kinetics of lipoxidation in almond-based products

Lipoxidation in almond-derived products was investigated using the chemiluminescence (CL) and thiobarbituric acid-reactive substances (TBARS) methods to detect the first and later reaction products, respectively. The effects of light during storage at 5 °C, 22 °C and 40 °C were studied, as well as the effects of combined heat/water activity treatments in the 60–120 °C and 0.38–0.72 range. During storage, light was found to enhance the CL and TBARS values, and specific responses were observed in almond paste and the final Calisson product. During the heating of almond paste, as the initial water activity (a_w) increased, the CL rate constants increased during heating to 60 °C and 80 °C, but interestingly, these values decreased during further heating to 120 °C, whereas the maximum TBARS rate constants occurred at a_w 0.57 at all the heating temperatures tested. The activation energies, based on the CL and TBARS values, decreased specifically when the a_w increased from 0.38 to 0.72, giving overall values ranging from110 kJ mol⁻¹ to 60 kJ mol⁻¹. Likewise, in the same water activity range, the temperature-dependent rate constant enhancing factor (Q₁₀) decreased from 3.3 to 1.6.     

Cultured C2C12 cell lines as a model for assessment of bacterial attachment to bovine primary muscle cells

The mechanisms of bacterial attachment to meat tissues need to be understood to enhance meat safety interventions. However, little is known about attachment of foodborne pathogens to meat muscle cells. In this study, attachment of six Escherichia coli and two Salmonella strains to primary bovine muscle cells and a cultured muscle cell line, C₂C₁₂, was measured, including the effect of temperature. At 37 °C, all but one strain (EC623) attached to C₂C₁₂ cells, whereas only five of eight strains (M23Sr, H10407, EC473, Sal1729a and Sal691) attached to primary cells. At 10 °C, two strains (H10407 and EC473) attached to C₂C₁₂ cells, compared to four strains (M23Sr, EC614, H10407 and Sal1729a) of primary cells. Comparing all strains at both temperatures, EC614 displayed the highest CFU per C₂C₁₂ cell (4.60 ± 2.02 CFU/muscle cell at 37 °C), whereas greater numbers of M23Sr attached per primary cell (51.88 ± 39.43 CFU/muscle cell at 37 °C). This study indicates that primary bovine muscle cells may provide a more relevant model system to study bacterial attachment to beef carcasses compared to cell lines such as C₂C₁₂.     

Quality assessment of wild European eel (Anguilla anguilla) stored in ice

The quality assessment of wild European eel (Anguilla anguilla) stored in ice and in boxes without ice (3 ± 1 °C) was investigated by the sensory analysis, levels of nucleotide breakdown products and biogenic amines for up to 19 days. Sensory analysis was assessed using the Tasmanian Food Research Unit Scheme. K and related values (K_i, G, P, H and F_r) were used as freshness indicators. Linear regressions (r²) obtained from K, K_i, G, P, H and F_r were 0.95, 0.96, 0.83, 0.96, 0.99 and 0.96, respectively, for eel stored in ice whereas, for eel kept in boxes without ice, the values were 0.86, 0.86, 0.96, 0.91, 0.98 and 0.86, respectively. When eel stored in ice and in boxes without ice were considered at the limit of acceptability by assessors at ∼12–14 days and ∼5–7 days, respectively, the average K, K_i and P values were ∼70–85%, H values were ∼60% and F_r values were ∼10% for both storage conditions. The level of histamine exceeded the legal limit (5 mg/100 g fish) in eel stored without ice after 6–7 days and, in ice, after 13–14 days of storage, at which time eels were rejected by the sensory panel. The concentrations of biogenic amines were higher in eel stored in boxes without ice than in eel kept in ice. The levels of histamine in the muscle of eel kept in boxes without ice and in ice increased to the maximum levels of 17.9 mg/100 g on day 12 and 12.6 mg/100 g on day 19, respectively.     

Ultraviolet irradiation: The generator of Vitamin D2 in edible mushrooms

Fresh Shiitake mushrooms (Lentinula edodes), Oyster mushrooms (Pleurotus ostreatus), Button mushrooms (Agaricus bisporus), and Abalone mushrooms (Pleurotus cystidus) were irradiated with Ultraviolet-A (UV-A; wavelength 315–400 nm), Ultraviolet-B (UV-B; wavelength 290–315 nm), and Ultraviolet-C (UV-C; wavelength 190–290 nm). Irradiation of each side of the mushrooms for 1 h, was found to be the optimum period of irradiation in this conversion. The conversions of ergosterol to vitamin D₂ under UV-A, UV-B, and UV-C were shown to be significantly different (p < 0.01). The highest vitamin D₂ content (184 ± 5.71 μg/g DM) was observed in Oyster mushrooms irradiated with UV-B at 35 °C and around 80% moisture. On the other hand, under the same conditions of irradiation, the lowest vitamin D₂ content (22.9 ± 2.68 μg/g DM) was observed in Button mushrooms.     

Oxidation promotes cross-linking but impairs film-forming properties of whey proteins

The objective of the study was to investigate the impact of oxidation on the film-forming properties of whey protein isolate (WPI). Sequential heating (70–90 °C) then oxidation (0.1 mM FeCl₃/1 mM ascorbate/0–20 mM H₂O₂) (H → O) or vice versa (O → H) were conducted to oxidize/unfold WPI at pH 6.8 and 8.0 before casting. The resulting films were characterized through mechanical, microstructural, and protein electrophoretic analyses. Oxidation promoted protein cross-linking mainly through disulfide bonds. Tensile strength (TS) and elongation at break (EAB) of films decreased for WPI oxidized by higher concentrations of H₂O₂. Film solubility (protein leachability) at pH 3–7, ranging from 20 to 40%, was unaffected by H₂O₂ up to 5 mM but reached almost 100% at above 5 mM H₂O₂ except at pH 4–5. β-Lactoglobulin dimers and its complex with α-lactalbumin were abundant in O → H WPI films and polymers of WPI dominated in H → O films. Microstructural images confirmed that oxidation promoted crumbly structures thereby explaining the reduced film-forming capability.     

Influence of salt and pH on the solubility and structural characteristics of transglutaminase-treated wheat gluten hydrolysate

Hydrolyzed wheat gluten (GH, 77–85% protein) was prepared by limited chymotrypsin digestion at 37 °C for 4 h (degree of hydrolysis = 6.4%) and 15 h (degree of hydrolysis = 10.3%). Microbial transglutaminase (MTGase) treatment (55 °C for 1 h, or 5 °C for 18 h) effect on the solubility and structural characteristics of GH was examined under selected food processing conditions (pH 4.0–7.0, 0–0.6 M NaCl). The MTGase treatment increased solubility of GH by 3–29-fold (P < 0.05) within pH 4.0–7.0. Addition of 0.6 M NaCl or changing the conditions of MTGase incubation did not significantly alter solubility characteristics of GH. The MTGase treatment decreased surface hydrophobicity, and increased carboxyl groups in GH, suggesting cross-linking and deamidation. Fluorescence and UV spectra attributed the improved GH solubility to MTGase-induced polar environment, and partial masking of some nonpolar aromatic amino acids possibly due to high-molecular-weight polypeptides formed.     

Optimisation of the solvent extraction of bioactive compounds from Parkia speciosa pod using response surface methodology

Central composite design was employed to optimise the buffer-to-solids ratio (X₁: 20–50 ml/g), incubation temperature (X₂: 35–55 °C) and time (X₃: 100–200 min), obtaining extracts from Parkia speciosa pod with high total phenolic and flavonoid contents and high antioxidant activities. Analysis of variance showed that the contribution of a quadratic model was significant for the responses. An optimisation study using response surface methodology was performed and 3D response surfaces were plotted from the mathematical models. The optimal conditions based on combination responses were: X₁ = 20 ml/g, X₂ = 35–36 °C and X₃ = 100–102 min. These optimum conditions yielded total phenolic contents of 664–668 mg gallic acid equivalents/100 g, total flavonoid contents of 47.4–49.6 mg pyrocatechol equivalents/100 g, %DPPH_sc of 81.2–82.1%, %ABTS_sc of 78.2–79.8% and FRAP values of 3.2–3.3 mM. Close agreement between experimental and predicted values was found. This methodology could be applied in the extraction of bioactive compounds in the natural product industry.     

Effect of sodium chloride, sodium nitrite and temperature on desorption isotherms of previously frozen beef

Moisture desorption isotherms of beef were determined in the relative humidity range of 23 to 90% at 5, 15 and 25 °C and at 2.5% NaCl and 2.5% NaCl + 150 ppm NaNO₂ content. Desorption isotherms were found to be typical type II sigmoid. The water content at equilibrium was higher in beef with NaCl and NaCl + NaNO₂ than control samples. Experimental data were fitted to various mathematical models and it was found that the Peleg model was best in describing the equilibrium moisture content relationship for beef samples over the entire range of temperatures. The net isosteric heat of sorption was estimated from equilibrium desorption data, using the Clausius-Clapeyron equation. Isosteric heats of desorption were found to increase with decreasing moisture content.     

Extraction, thermal stability and kinetic behavior of pectinmethylesterase from hawthorn (Crataegus pubescens) fruit

Pectinmethylesterase (PME) extracted from hawthorn (Crataegus pubescens) fruit was evaluated for its thermal stability and kinetic behavior. The enzyme extraction process was established after studying different NaCl concentrations (0.5-3.0 moles/L). A maximum PME extraction of 51.61 units/mg protein was obtained using 2 moles/L NaCl. Kinetic parameters (K_m and V_max) were determined using a commercial citrus pectin and C. pubescens pectin as substrates. The effects of NaCl concentration, pH and temperature on PME activity were investigated. PME showed higher affinity for C. pubescens pectin (K_m and V_max of 2.84 mg/mL protein, and 64.10 units/mg protein, respectively) than for citrus pectin. C. pubescens PME extract showed maximum activity at 0.4 moles/L NaCl, pH 7.5, and 55 °C. The E_a and Q₁₀ for thermal activation were 36.27 kJ/mol and 2.01 (20-30 °C), respectively. About 50% of the activity still remained after heating for 25 min at 60 °C, and it was completely inactivated by incubation at 80 °C for 10 min. The Q₁₀ and E_a values for thermal inactivation reaction were 20.06 (70-80 °C) and 146.16 kJ/mol, respectively. These results provide useful information about the factors that affect the activity of C. pubescens PME, and might be used as a starting point for texture control during post-harvest handling and processing of this fruit.     

Artificial intelligence in predicting extraction of anti-cancer compounds

Saponins from the particulate Saponaria vaccaria L. seeds (0.29–0.84 mm, 15.35–61.40 g H₂O/100 g dry mass) were extracted for methanol concentrations (MeOH) of 30, 50, 70, and 90 mL/100 mL H₂O and temperatures (T) of, 30, 45, and 60 °C at ten extraction intervals (t) between 1 and 180 min. A calibration equation was developed from the liquid-chromatogram–mass spectroscopy peaks to quantify the extract yields (mg mL⁻¹) for various types of saponins. An artificial neural network (ANN) with three inputs, MeOH, T, and t predicted the extraction kinetics and the yields with less than ca. 12% error. The ANN model not only slightly outperformed the numerical diffusional model, but it also made the prediction simple and faster eliminating the use of the partition coefficient and the effective diffusivity. Therefore an ANN model can be a right approach to predict the yields of saponins and similar products.     

Breaking the spores of the fungus Ganoderma lucidum by supercritical CO2

The hard sporoderm of Ganoderma lucidum spores prevents the release of bioactive components such as polysaccharides which have significant anti-tumour activity. In the present study, supercritical carbon dioxide (SC–CO₂) was used for the sporoderm breaking of G. lucidum spores, and polysaccharides were subsequently extracted and determined for evaluating the performances of SC–CO₂. The operating parameters were optimized by orthogonal array design (OAD), and the morphological status of sporoderm was observed by scanning electron microscope (SEM). The optimum operating conditions for SC–CO₂ breaking of sporoderm were as follows: pressure 35 MPa, temperature 25 °C, time 4 h, and CO₂ flow rate 10 kg/h. After SC–CO₂ processing, the extraction yield of polysaccharides reached 2.98%, which was 3-fold to that of the intact ones (0.94%). This method is fast, efficient and advanced enough to break the hard sporoderm of G. lucidum, which may provide a scientific reference for the large-scale processing of spores in the pharmaceutical and food industries.     

Extraction of β-carotenes from palm oil mesocarp using sub-critical R134a

Sub-critical extraction of palm oil from palm mesocarp using R134a solvent was conducted via the dynamic mode to investigate the ability of R134a to extract β-carotene. The yield of palm oil and the solubility of β-carotene were investigated at 40, 60 and 80 °C and pressure range from 45–100 bar. The extracted oil was analysed for β-carotene content using UV–Vis spectrophotometry. The results showed that palm oil yield increased with pressure and temperature. The maximum solubility of β-carotene was obtained at 100 bar and 60 °C while the lowest solubility occurred at 80 bar and 40 °C. The higher concentration of extracted β-carotene ranging from 330–780 ppm as compared to that achieved through conventional palm oil processing indicates that extraction of β-carotene using R134a is viable.