Solubility determination as an alternative to migration measurements

Solubility values for six UV stabilisers (Cyasorb UV-1164, Tinuvin P, Tinuvin 234, Tinuvin 326, Tinuvin 327 and Tinuvin 1577) and five antioxidants (Irgafos 168, Irganox 1010, Irganox 3114, Irganox 3790 and Irganox 565) were determined in all the liquid food simulants (3% (m/V) acetic acid–water mixture, 10% (V/V), 20% (V/V), 50% (V/V) ethanol–water mixture and vegetable oil) proposed in European Union Regulation No. 10/2011/EC, as well as in fruit juice and cola drink. The applied method was obtained by modification of the method for the determination of water solubility as described in OECD guideline Test No. 105. By using ultrasonication and shorter equilibration time, the time demand of the solubility determinations were decreased notably. Solubility values proved to be lower than the specific migration limits (as specified in 10/2011/EC) at 25°C for almost all target compounds in food simulants A, B, C and D1 as well as in fruit juice and cola drink. The exceptions were Tinuvin P and Irganox 3790 in simulant D1. The solubility in food simulant D2 was higher than 1000 µg ml^–1 for all target compounds. These results show that the solubility of some additives in food simulants can be so low that it makes migration studies for certain additive–food simulant pairs dispensable.     

Influence of postharvest UV‐C treatment on refrigerated storage of minimally processed broccoli (Brassica oleracea var. Italica)

Minimally processed broccoli was treated with UV‐C light (8 kJ m^?2) and subsequently stored for 21 days at 4 °C. The UV‐C treatment delayed yellowing and chlorophyll degradation during storage. Treated broccoli florets displayed lower electrolyte leakage and respiratory activity, indicating higher tissue integrity. Treated samples showed higher phenolic and ascorbic acid contents as well as higher antioxidant activity than controls. Treated samples also had a higher content of soluble sugars, but no differences in the content of soluble proteins between control and treated samples were detected. The UV‐C treatment also affected bacterial and mould populations. After 21 days at 4 °C the number of colony‐forming units of both populations was lower in treated than in control broccoli florets. The results suggest that UV‐C treatment reduces tissue damage of minimally processed broccoli during storage at 4 °C, thus maintaining nutritional quality and reducing microbial growth. Copyright © 2007 Society of Chemical Industry     

Effect of gelatin/agar bilayer film incorporated with TiO2 nanoparticles as a UV absorbent on fish oil photooxidation

This research evaluated the effect of gelatin/agar bilayer film and nanocomposites containing different concentrations of TiO₂ nanoparticles (0.5%, 1% and 2%) as ultraviolet (UV) and oxygen barriers on the oxidative stability of fish oil. Samples of fish oil covered with the bilayer films were stored under UV light or in darkness and with or without lids at 18 °C for 12 days. Oil quality in terms of peroxide values (PV), thiobarbituric acid (TBA), conjugated diene (CD), fatty acids profile and colour change (?E) was monitored during storage. Fish oil photooxidation was hindered by increasing TiO₂ concentration, so that nanocomposite containing 2% of the nanoparticles could control photooxidation, similar to the samples stored in darkness. Furthermore, upon studying both photooxidation and autoxidation, the highest amounts of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), as well as the lowest amount of changes in PV, TBA, CD and ?E, were observed in oils covered with the nanocomposites.     

The effect of intermittent shaking, headspace and temperature on the growth of Alicyclobacillus acidoterrestris in stored apple juice

The presence of Alicyclobacillus acidoterrestris in stored juices can be difficult to detect. In this study the effects of storage temperature, headspace and agitation of juice containers was investigated. The results indicate that the amount of headspace has a significant effect on growth of vegetative cells and spores of A. acidoterrestris at 35 °C. Intermittent shaking before sampling increased growth and therefore probable detection rates at 30 °C, Agitating containers and sampling from several areas within containers is therefore recommended for determining whether A. acidoterrestris is present or absent from stored juice, especially in large containers.     

Ascorbyl Palmitate Efficacy in Enhancing the Accelerated Storage Stability of Canola Oil

The effect of various levels of ascorbyl palmitate (AP) and of butylated hydroxyanisole/toluene (BHA/BHT) on the accelerated storage stability of canola oils was determined by sensory, gas liquid chromatographic (GLC) and chemical evaluations. In Schaal oven tests (65°C, 0–16 days), chemical, GLC and trained sensory panel data indicated that 200 ppm AP retarded autoxidation in stored canola oils. Monoglyceride citrate (MGC) addition to oils containing 200 ppm AP did not enhance oil stability. Fluorescent light tests (7500 lux, 24°C, 0–24 hr) showed that 200 ppm AP, with or without MGC, had a limited effect in protecting canola oil from photooxidation. BHA/ BHT, at 100 ppm each, with MGC, did not improve canola oil stability.     

Physical Properties and Oxidation Rates of Unrefined Menhaden Oil (Brevoortia patronus)

ABSTRACT: Unrefined menhaden oil was evaluated for thermal and rheological properties and its temperature-dependent viscosity and lipid oxidation rate were determined. Peroxide value, free fatty acids, density, specific gravity, water activity, moisture content, and enthalpy of the unrefined menhaden oil were 5.70 meq/kg, 3.80%, 0.93 g/mL, 0.93%, 0.52%, 0.15%, and 20.2 kJ/kg, respectively. The melting point range of unrefined menhaden oil was found to be −69.5 to 27.21 °C. The menhaden oil exhibited non-Newtonian fluid behavior at lower temperatures (5 to 25 °C), while it behaved like a Newtonian fluid at 30 °C. The oil apparent viscosity at 5 °C (0.22 Pa.s) was significantly higher (P < 0.05) than that at 30 °C (0.033 Pa.s). The average magnitude of activation energy for viscosity of the unrefined menhaden oil was 50.37 kJ/mol. The predicted apparent viscosity agreed (R²= 0.9837) satisfactorily with the experimental apparent viscosity. The minimal lipid oxidation rate of the oil was found at 25 and 35 °C for 6 h, higher lipid oxidation rates were observed when the oil was heated for 6 h at 45 to 85 °C. The rate of lipid oxidation for unrefined menhaden oil was temperature dependent (R²= 0.9425). This study showed that the magnitude of the apparent viscosity and oxidation rate of the unrefined menhaden oil was greatly influenced by temperature.     

Superoxide dismutase from hen’s egg yolk can protect fatty acids from peroxidative damage

Superoxide dismutase (SOD, EC1.15.1.1) is a family of enzymes, which remove superoxide anion (O ₂ ^·? ) from the cells of living organisms. The aim of this study was to describe antioxidative properties of SOD with regard to the protection of unsaturated fatty acids (UFA) from peroxidative damage and to compare this effect with butylated hydroxytoluene (BHT). In this experiment, Cu, Zn-SOD from hen’s egg yolk with a mass of 15.59 ± 0.38 kDa and pI 6.58 ± 0.10, 6.41 ± 0.08 and 6.30 ± 0.15 was used to protect fatty acids from peroxidative damage in vegetable oil (sunflower oil and olive oil) during 200 days of storage at different temperatures—4, 20 and 35 °C. Antioxidative properties of SOD and BHT were expressed as the ratio of unsaturated to saturated fatty acids (SFA) in samples after 50, 100 and 200 days of storage as well as the percentage content of selected fatty acids in the examined oils. SOD from egg yolk showed the same or better antioxidant properties with regard to the concentration of linoleic acid (C18:2) contained in sunflower oil and olive oil than the corresponding concentrations of BHT during 200-day storage at 4, 20 and 35 °C. The concentration of linoleic acid (C18:2) in the sample with SOD was significantly higher during storage at 35 °C on day 200. At all storage temperatures, the ratio of SFA to UFA in samples with the addition of SOD was statistically higher than in oils stored without the antioxidant. With regard to linoleic acid (C18:2), SOD proved to be a better antioxidant than BHT. The results demonstrated better antioxidant properties of SOD from hen’s eggs compared with the same concentrations of BHT at elevated temperatures (at 20 and 35 °C) in oil with a high content of UFA. No negative antioxidative effect (worse than that of BHT at a corresponding concentration) of the addition of SOD from egg yolk on fatty acid composition of the tested samples was observed. Though further research is necessary, SOD from hen’s egg yolk seems to be a promising natural antioxidant of vegetable oils.     

Effects of monoacylglycerols on the oil oxidation of acidic water/perilla oil emulsion under light in the presence of chlorophyll

Monoacylglycerol (MAG) effects on the oil photooxidation of an emulsion containing chlorophyll were studied. The emulsion consisted of equal weights of hexaneextracted perilla oil and 0.5% acetic acid, and 4 ppm chlorophyll b and MAG at 0, 1, or 1.5% were added. The oxidation was performed under 1,700 lx light at 25°C for 48 h. Singlet oxygen was involved in the oil oxidation of the emulsion containing chlorophyll under light. MAG protected chlorophyll and polyphenol compounds from degradation during the oxidation of the emulsion under light. MAG significantly decreased and decelerated headspace oxygen consumption and hydroperoxide production in the emulsion, and thus acted as antioxidant in photooxidation of the acidic water/perilla oil emulsion containing chlorophyll. Antioxidant activity of MAG in the photooxidation of the emulsion could be due to combined results of increased retention of polyphenols and decreased oxygen diffusion by forming a physical barrier.     

Attachment of Listeria monocytogenes to Stainless Steel Surfaces at Various Temperatures and pH Values

The attachment of Listeria monocytogenes isolates Scott A and Jalisco Cheese to stainless steel surfaces at 35°, 21°, and 10°C was investigated using scanning electron microscopy (SEM). Cells were found to adhere at all three temperatures, but cells with fibrils were observed only at 21°C. When grown at pH 8, the attachment matrix was more prevalent at 21°C than at 35°C and may also be related to the length of incubation time at 21°C. It appears that adherence may be related to the flagella and any exopolymer surrounding the cells.     

Effect of heating oils and fats in containers of different materials on their trans fatty acid content

BACKGROUND: The nature of the container material and temperature employed for deep‐frying can have an influence on the development of trans fatty acids (TFAs) in the fat used. The present study was undertaken to determine the effect of heating vegetable oils and partially hydrogenated vegetable fats with different initial TFA content in stainless steel, Hindalium (an aluminium alloy), cast iron and glass containers. Ground nut oil (oil 1), refined, bleached and deodorised (RBD) palmolein (oil 2) and two partially hydrogenated vegetable oils with low (fat 1) and high (fat 2) TFA content were uniformly heated at 175–185 °C over a period of 12 h. RESULTS: An increase in TFA content to 20 g kg^?1 was observed in oil 2 in the cast iron container, while a decrease in TFA content of 20–30 g kg^?1 was observed in fat 2 in all containers. The heating process of fats and oils also led to an increase in Butyro refractometer reading and colour values. CONCLUSION: This study showed that the TFA 18:1t content of oil 1, oil 2 and fat 1 increased with repeated or prolonged heating. The cast iron container showed the highest increase in TFA 18:1t for RBD palmolein (oil 2). The amount of linoleic acid trans isomers formed in the heating process was negligible. Fat 2 with high initial TFA content showed a decrease in TFA 18:1 and 18:2 on heating in all containers. Oils heated in glass and stainless steel containers showed less TFA 18:1t formation. Copyright © 2012 Society of Chemical Industry     

Alleviation of chilling injury in postharvest tomato fruit by preconditioning with ultraviolet irradiation

BACKGROUND: Tomato fruit is usually stored at low temperatures for delayed ripening and extended shelf life. However, tomato fruit is susceptible to chilling injury when exposed to low temperatures. In this study, the potential effects of preconditioning with UV‐C or UV‐B irradiation on chilling injury of postharvest tomato fruit were investigated. RESULTS: Mature–green tomato fruit were exposed to 4 kJ m^?2 UV‐C or 20 kJ m^?2 UV‐B irradiation and stored for 20 days at 2 °C and subsequently 10 days at 20 °C. UV irradiation was effective in reducing chilling injury index and delaying ethylene peak. Furthermore, UV irradiation preserved storage quality as manifested by reduced weight loss, better retention of firmness, and higher contents of total soluble solids, soluble protein and soluble sugar during subsequent storage at 20 °C. UV‐C irradiation significantly delayed the development of the red colour after 10 days of storage at 20 °C. On the other hand, UV irradiation decreased total phenolics content and antioxidant capacity, suggesting possibly reduced stress response to low temperature resulted from enhanced physiological adaptation by UV preconditioning. CONCLUSION: Our results suggest that preconditioning with UV‐C or UV‐B irradiation in appropriate doses had a positive effect on alleviating chilling injury in postharvest tomato fruit. Copyright © 2012 Society of Chemical Industry     

UV‐C irradiation reduces breakdown and chilling injury of peaches during cold storage

Pre‐storage exposure of peaches (Prunus persica cv Jefferson) with UV‐C irradiation for 3, 5 or 10 min significantly reduced chilling injury after 14 and 21 days of storage at 5 °C plus 7 days of shelf‐life at 20 °C. Similar reduction in fungal decay was also found by these treatments. Skin browning and UV damage were found to be moderate to severe in peaches after the 15 or 20 min of UV‐C treatments. The 20 min of exposure accelerated deterioration. Fruit treated with UV‐C for 3, 5 or 10 min remained firmer and softened more slowly than the control and those treated with longer durations of exposure. No differences were found in weight loss or respiration rates among the treatments. However, ethylene production was stimulated by all of the UV‐C treatments compared with the control. Putrescine levels increased initially after 3 or 5 min of exposure to UV‐C. A tendency toward higher accumulation of spermidine and spermine was found in peaches after UV exposure. These higher levels of polyamines apparently are a response to the UV‐C irradiation and might be beneficial in increasing the resistance of fruit tissue to deterioration and chilling injury. Copyright © 2004 Society of Chemical Industry     

Antioxidant activity of ginger extract in sunflower oil

The antioxidant activity of dichloromethane extract from ginger was evaluated during 6 months of storage of refined sunflower oil at 25 and 45 °C. Free fatty acid (FFA) content, peroxide value (POV) and iodine value (IV) were used as criteria to assess ginger extract as an antioxidant. After 6 months of storage at 45 °C, sunflower oil containing 1600 and 2400 ppm ginger extract showed lower FFA contents (0.083 and 0.080%) and POVs (24.5 and 24.0 meq kg^?1) than the control sample (FFA contents 0.380%, POV 198.0 meq kg^?1). Sunflower oil containing 200 ppm butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) showed FFA contents of 0.089 and 0.072% and POVs of 26.5 and 24.7 meq kg^?1 respectively after 6 months of storage at 45 °C. Similarly, after 6 months of storage at 45 °C, IVs of sunflower oil containing 1600 and 2400 ppm ginger extract were 80 and 92 respectively, higher than that of the control sample (53). However, IVs of sunflower oil treated with 200 ppm BHA and BHT were 94 and 96 respectively after 6 months of storage at 45 °C. These results illustrate that ginger extract at various concentrations exhibited very strong antioxidant activity, almost equal to that of synthetic antioxidants (BHA and BHT). Ginger extract also showed good thermal stability and exhibited 85.2% inhibition of peroxidation of linoleic acid when heated at 185 °C for 120 min. Therefore the use of ginger extract in foods is recommended as a natural antioxidant to suppress lipid oxidation. © 2003 Society of Chemical Industry     

Development of an improved extraction and HPLC method for the measurement of ascorbic acid in cows' milk from processing plants and retail outlets

An improved extraction (2.5% HPO₃, 5 mm dithiothreitol) and HPLC quantification methodology using a C–18 column at 35 °C and 0.1 m acetic acid (98%) and acetonitrile (2%) mobile phase was developed to quantify total ascorbic acid (AA) in commercial whole/semi‐skim/skim raw/pasteurised/UHT milk packaged in opaque bags, transparent plastic, cardboard and Tetra Brik^?. AA content ranged from 0.21 to 10 and from 3.4 to 16 mg L^?1 in milk from retail outlets and processing plants, respectively, and was higher in organic milk. For same processor/lot samples, pasteurised milk showed higher AA content than UHT milk. This was not true for retail outlets samples. AA content was similar for whole/semi‐skim and semi‐skim/skim milk, but not for whole/skim comparisons. Among UHT samples, the AA content trend was whole<semi‐skim<skim and lower for UHT milk in opaque plastic and Tetra Brik^? container. After 14 days at 4 °C in the dark, AA losses ranged 35–83% depending on milk type and preservation method with a higher AA retention in unopened containers.     

Use of UV-C treatments to maintain quality and extend the shelf life of green fresh-cut bell pepper (Capsicum annuum L.)

Abstract: The objective of this work was to select a Ultraviolet‐C (UV‐C) treatment for fresh‐cut mature green bell pepper, and to evaluate the effect of its combination with refrigeration on quality maintenance. Bell pepper sticks were treated with 0, 3, 10, or 20 kJ/m² UV‐C in the outer (O), inner (I), or both sides of the pericarp (I/O) and stored for 8 d at 10 °C. During the first 5 d of storage, all UV‐C treatments reduced deterioration as compared to the control. The treatment with 20 kJ/m² I/O was the most effective to reduce deterioration, and was used for further evaluations. In a second group of experiments, mature green bell pepper sticks were treated with 20 kJ/m² I/O, stored at 5 °C for 7 or 12 d and assessed for physical and chemical analysis, and microbiological quality. UV‐C‐treated fruit showed lower exudates and shriveling than the control. UV exposure also reduced decay, tissue damage, and electrolyte leakage. After 12 d at 5 °C, UV‐C irradiated peppers remained firmer and had higher resistance to deformation than the control. The UV‐C treatments also reduced weight loss and pectin solubilization. UV‐C exposure decreased the counts of mesophile bacteria and molds, and did not affect acidity or sugars. UV‐C‐treated fruit stored for 0 or 7 d at 5 °C did not show major differences in antioxidants from the control as measured against DPPH^? or ABTS^?+ radicals. Results suggest that UV‐C exposure is useful to maintain quality of refrigerated fresh‐cut green pepper. Practical Application: Exposure to UV‐C radiation before packing and refrigeration could be a useful nonchemical alternative to maintain quality and reduce postharvest losses in the fresh‐cut industry.     

A Study on the Growth Potential of Staphylococcus aureus In Boletus edulis, A Wild Edible Mushroom, Prompted by a Food Poisoning Outbreak

A dish of Boletus edulis, a wild edible mushroom, in vinegar caused staphylococcal food poisoning in 13 of 35 diners in a restaurant. Enterotoxicosis was confirmed by detection of toxins A and D in the dish. Staphylococcus aureus growth potential in B. edulis was studied by inoculating fresh and frozen and thawed bolete with S. aureus strains VTTE 530, 757, 793 and 805 and storing for 3 days at 15 and/or 21°C. Essentially no staphylococcal growth was observed in frozen and thawed mushrooms contaminated with strains 530, 793 or 805 and stored at 15 or 21°C. In fresh B. edulis the same strains showed slight growth at 21°C. Frozen and thawed bolete inoculated with strains 530 and 757 (isolated from mushroom soup, nonenterotoxigenic) supported staphylococcal growth in 2 days at 21°C from a level of 4.8±10⁴ and 5.4±10³ to 2.0±10⁶ and 7.0±10₇ cfu/g, respectively. Enterotoxin was not detected in these samples.     

Unhydrogenated Palm Oil as a Stabilizer for Peanut Butter

Response surface methodology was used to investigate the potential of unhydrogenated palm oil (PO), with and without peanut shell flour (PSF), to prevent oil separation in peanut butter. Percent oil separation, texture and color attributes were measured after 0, 1 and 2 wk storage at 15, 25 and 35°C. Computer-generated contour plots indicated that 2.0–2.5% PO should effectively stabilize peanut butter stored at 21–24°C for ≥ 1 year without affecting color. PSF (≥ 0.8%) decreased L value of color by a 5% but did not increase firmness of experimental products containing PO. Samples stabilized with PO were softer than those containing a commercial stabilizer.     

Increased quality and functionality of kimchi when fermented in Korean earthenware (onggi)

Kimchi was fermented in onggi and other containers at 4 °C for 4 weeks. Two types of onggi were used: glazed and nonglazed onggi. Other containers such as polyethylene plastic containers, polypropylene containers for use in a kimchi refrigerator, stainless steel and glass bottles were used. During the fermentation, kimchi fermented in onggi showed relatively stable acidity change compared with those in the other containers. Also it showed higher lactic acid bacteria multiplication (10⁸–10⁹ cfu g^?1 at 4th week) but slower general aerobic bacteria multiplication than the others. The springiness of kimchi fermented in onggi was more than 50% at 4th week, it is higher than the others. Its carbonic acid taste and overall acceptability were excellent in sensory evaluations. The antioxidative and cancer‐cell antiproliferative activities were also greater in kimchi fermented in onggi than the others. Between the two types of onggi, nonglazed onggi showed better results in both properties and functionalities of kimchi. Onggi showed higher gas permeability than polyethylene plastic containers and glass bottles because of its porous structure, and lactic acid bacteria could have benefited from this condition. It possibly contributes to optimal ripening of kimchi resulting in better properties, especially texture and taste, and health functionalities.     

Contribution of minor compounds to the singlet oxygen-related photooxidation of olive and perilla oil blend

This study evaluated contribution of natural minor compounds including carotenoids, tocopherols, polyphenols, and phosphatidylcholine (PC) to the stability of chlorophyll sensitized oxidation of olive and perilla oil blend under 2,500 lx light at 25°C for 48 h. The oxidation of the oil blend was evaluated by headspace oxygen consumption and peroxide values (POV). Minor compounds were also monitored. The headspace oxygen consumption and POV of the oil blend were increased with oxidation time; however, fatty acid composition was not significantly changed. Carotenoids, tocopherols, polyphenols, and PC were degraded during the oil oxidation, which was closely related with their singlet oxygen quenching. Correlations of the oil oxidation were higher with contents of carotenoids and PC (r ²>0.93) than with those of tocopherols or polyphenols, suggesting high contribution of carotenoids and PC to decreasing singlet oxygen-related photooxidation of olive and perilla oil blend.     

Antioxidant activity of sage extracts in rapeseed oil irradiated with UV‐rays

The antioxidant activities of sage acetone oleoresin and its methanol‐water fractions were tested in rapeseed oil at 0.1% concentrations and 80°C temperature after irradiation with UV‐rays (exposition 0.5 h). It was determined that even little doses of UV irradiation induce oxidation process in rapeseed oil samples both with additives and without them. The antioxidant activity of a synthetic antioxidant BHT was much lower than that of the sage fractions at 80°C and forced air oven conditions. This finding proves the advantage of sage extracts in comparison with BHT at high temperatures. It was also found that methanol‐water fraction separated from acetone oleoresin had the highest antioxidant activity in terms of the formation of primary and secondary oxidation products. Oil sample with this additive had the highest protection factor (PF = 4.53) when the oil was not irradiated with UV rays. The data obtained showed that all sage extracts had very strong antioxidant activity (PF > 3).