Ultra-high pressure LC for astaxanthin determination in shrimp by-products and active food packaging.

Nowadays, there is increasing interest in natural antioxidants from food by-products. Astaxanthin is a potent antioxidant and one of the major carotenoids in crustaceans and salmonids. An ultra-high pressure liquid chromatographic method was developed and validated for the determination of astaxanthin in shrimp by-products, and its migration from new packaging materials to food simulants was also studied. The method uses an UPLC® BEH guard-column (2.1 × 5 mm, 1.7 µm particle size) and an UPLC® BEH analytical column (2.1 × 50 mm, 1.7 µm particle size). Chromatographic separation was achieved using a programmed gradient mobile phase consisting of (A) acetonitrile-methanol (containing 0.05 m ammonium acetate)-dichloromethane (75:20:5, v/v/v) and (B) ultrapure water. This method was evaluated with respect to validation parameters such as linearity, precision, limit of detection, limit of quantification and recovery. Low-density polyethylene films were prepared with different amounts of the lipid fraction of fermented shrimp waste by extrusion, and migration was evaluated into food simulants (isooctane and ethanol 95%, v/v). Migration was not detected under the tested conditions.

Release of butylated hydroxytoluene from an active film packaging to Asadero cheese and its effect on oxidation and odor stability.

Antioxidant active packaging consisting of coextruded films made of low density polyethylene (LDPE) added with 0, 8, and 14 mg/g of butylated hydroxytoluene (BHT) and polyamide 6/66 were fabricated. The release of BHT from the films to Asadero cheese was determined. Most of the BHT was diffused from the LDPE layer to the cheese during the first 20 d of storage at 5 degrees C. Diffusion coefficient for the diffusion of BHT from the films 8 and 14 to the cheese was calculated as 6.24E-12 and 6.26E-12 cm2/s, respectively. The release of BHT from the film added with 8 mg/g of the antioxidant in the LDPE layer complied with the legal limit established for food products. However, the film added with 14 mg/g of the antioxidant exceeded that limit. The film added with 8 mg/g of BHT maintained the same levels of oxidized odor from 20 to 100 d of storage.

Migration of bisphenol A (BPA) from can coatings into a fatty-food simulant and tuna fish.

The effect of heat processing, storage time and temperature on the migration of bisphenol A (BPA) from organosol and epoxy can coatings to a fatty-food simulant and tuna was determined. Analyses of BPA were performed by RP-HPLC with fluorescence detection. Four migration experiments, performed between 2000 and 2003, using cans with organosol, epoxy and a combination of both types of coatings were performed under different processing conditions and storage times. Migration levels as high as 646.5 microg kg(-1) BPA from an organosol coating of tuna fish cans were found using a fatty-food simulant following the heat processing of the simulant-filled cans. Levels ranging from 11.3 to 138.4 microg kg(-1) BPA from tuna cans coated with an epoxy resin migrated to the fatty-food simulant during 1 year at 25 degrees C. Levels of BPA migration into a fatty-food simulant from thermally processed and stored tuna cans coated with a combination of organosol and epoxy resins and from vegetable cans coated with an epoxy resin were below the limit of quantitation of 10.0 microg kg(-1). Migration of BPA to tuna ranged from <7.1 to 105.4 microg kg(-1) during long-term storage at 25 degrees C. BPA levels in tuna cans purchased from three local supermarkets ranged from <7.1 to 102.7 microg kg(-1). The highest migration levels were found following heat processing at temperatures as high as 121 degrees C and at times as long as 90 min. Coatings from different can batches can give different levels of BPA migration. The migration levels of BPA found in this work are below the present European Union migration limit, except the 646.5 microg kg(-1) found after the commercial heating process was applied to the simulant-filled cans coated with the organosol resin.

Effect of heat processing and storage time on migration of bisphenol A (BPA) and bisphenol A-diglycidyl ether (BADGE) to aqueous food simulant from Mexican can coatings.

Effects of heat processing and storage time (up to 70 days) on migration of bisphenol A (BPA) and bisphenol A-diglycidyl ether (BADGE) from can coatings into an aqueous food simulant were determined. Distilled water was canned in two types of Mexican cans: for tuna and for jalapeño peppers. Results showed that there is an effect of heat treatment on migration of both compounds. Storage time did not show any effect in BPA migration from tuna cans. There was an effect of storage time on BPA migration from jalapeño pepper cans. Results for BADGE migration were affected by its susceptibility to hydrolyze in aqueous simulants. BADGE concentration decreased, or was not detected, during storage in both types of cans. Migration levels for BPA and BADGE were within 0.6-83.4 and <0.25-4.3 microg/kg, respectively. Both were below European and Mercosur legislation limits. Other migrating compounds were detected, although no identification was performed.

Migration from polyamide 'microwave and roasting bags' into roast chicken.

Migration of non-volatile and volatile compounds from 'microwave and roasting bags' (MRB), made of Nylon 6,6 (and some Nylon 6), into chicken meat, skin, and juices during roasting (200 degrees C/2 h) in a conventional oven was determined. For measurement of migration of non-volatile compounds, cooked chicken was freeze-dried, extracted with methanol after addition of 2-azacyclononane (internal standard) and the extract cleaned-up using liquid-solid adsorption chromatography (silica gel). High performance liquid chromatography (HPLC) in the reverse phase mode using a linear gradient of methanol in water was used to quantify seven Nylon 6 and Nylon 6,6 cyclic monomers and oligomers of molecular mass up to 678 daltons. Migration into chicken was 7.48 micrograms/g (8.26 mg/bag; 3.94 micrograms/cm2), 16% of the total non-volatile compounds contained in the MRB material. Individual migrants were also quantified. Migration of one volatile compound, 2-cyclopentyl cyclopentanone, into the roast chicken parts was measured. Extraction with diethyl ether, using a modified Likens-Nickerson system of concurrent steam distillation-solvent extraction with an internal standard (cyclohexanone) was performed for 10 h. Gas chromatography/mass spectrometry (GC/MS) in the selected ion mode (SIM) was used for quantification. An average of 14.0 (+/- 4.36) micrograms/bag (or micrograms/chicken) migrated, being 0.08% of the total 2-cyclopentyl cyclopentanone present in MRB. Loss of volatile compounds to the atmosphere is believed to have occurred since there was another, more volatile compound (cyclopentanone), present in MRB, at levels higher than 2-cyclopentyl cyclopentanone, but this was not detected in roast chicken. In general, the transference of MRB components into roast chicken can be considered not to present a hazard.

Determination of potential migrants present in Nylon 'microwave and roasting bags' and migration into olive oil.

Two groups of potential migrants were found in Nylon "microwave and roasting bags' (MRBs): volatile compounds were released at cooking temperatures and non-volatile compounds were extracted with methanol and/or water. A dynamic headspace system at 200 degrees C followed by gas chromatography (GC) coupled to mass spectrometry (MS) was used for determination of volatile compounds. Cyclopentanone (31.7 mg/bag), 2-cyclopentyl cyclopentanone (17.4 mg/bag), hexadecane (2.6 micrograms/bag), heptadecane (3.2 micrograms/bag), octadecane (3.0 micrograms/bag) and epsilon-caprolactam (5.0-35.5 mg/ bag) were the main volatile compounds present in the MRBs. High performance liquid chromatography (HPLC) and mass spectrometry were combined for identification and quantification of non-volatile compounds extracted with methanol (46.0 mg/bag). Nylon 6,6 cyclic monomer and cyclic oligomers up to the tetramer and Nylon 6 monomer and cyclic oligomers up to the octamer were identified and quantified, confirming that the plastic was made of Nylon 6,6 and Nylon 6 polymers. The same non-volatile compounds (except Nylon 6 heptamer and octamer) were found to migrate into olive oil at 175 degrees C for 1 h. A total of 0.916 mg/dm2 (19.2 mg/bag) of non-volatile compounds migrated into olive oil (41.8% of those quantified in the plastic material).

[Isolation and partial characterization of phenoloxidase from apples (Malus domestica, var. Anna)]. / Aislamiento y caracterización parcial de la enzima fenoloxidasa de manzana (Malus domestica, var. Anna).

This study pursued the isolation and partial characterization of the enzyme polyphenoloxidase from apple (Malus domestica Anna variety), grown in the Hermosillo Coast (State of Sonora, Mexico). The effects of pH and temperature as well as its specificity towards substrates, and its behavior under conditions of hydrophobic chromatography, were studied. The enzyme was isolated from a residual powder obtained from ripe apples homogenized with cold acetone. The extract thus prepared was used to characterize the enzyme, and it showed an optimum pH of 5.36 and an optimum temperature of 35 degrees C. The substrate specificity proved to decrease from 4-methyl catechol, chlorogenic acid, catechol, and caffeic acid, to 3,4-dihydroxiphenyl alanine (DOPA). The enzyme resulted to be more thermostable (temperature range: 35 degrees C to 60 degrees C) than the rest of oxidases of plant origin. When the extract was eluted under conditions of hydrophobic chromatography separation, it appeared as a single peak resulting in a 300 fold purification. The phenolase activity characteristics found in the present study were similar to those observed in other apples from temperate climates; however, this particular polyphenoloxidase is more thermostable under natural conditions. This explains why apples of the Anna variety, at the high harvesting temperature, show a very fast formation of brown spots even when there is a minor damage. The content of compounds with phenolic group was high (1.16 g/100 g fresh weight). Further increase of the velocity of fruit enzymatic browning was due to this reason.