Heavy metal, total arsenic, and inorganic arsenic contents of algae food products

The total arsenic, inorganic arsenic, lead, cadmium, and mercury contents of 18 algae food products currently on sale in Spain were determined. The suitability of the analytical methodologies for this type of matrix was confirmed by evaluating their analytical characteristics. The concentration ranges found for each contaminant, expressed in milligrams per kilogram of dry weight, were as follows: total arsenic, 2.3-141; inorganic arsenic, 0.15-88; lead, < 0.05-1.33; cadmium, 0.03-1.9; and mercury, 0.004-0.04. There is currently no legislation in Spain regarding contaminants in algae food products, but some of the samples analyzed revealed Cd and inorganic As levels higher than those permitted by legislation in other countries. Given the high concentrations of inorganic As found in Hizikia fusiforme, a daily consumption of 1.7 g of the product would reach the Provisional Tolerable Weekly Intake recommended by the WHO for an average body weight of 68 kg. A more comprehensive study of the contents and toxicological implications of the inorganic As present in the algae food products currently sold in Spain may be necessary, which might then be the basis for the introduction of specific sales restrictions.     

Free galactose concentrations in fresh and stored apples (Malus domestica) and processed apple products

Gas chromatography was used to quantitate free galactose in Braeburn, Fuji, Red Delicious, and Spartan apples during cold storage, after thermal processing of apple slices and in juice produced using clarification and/or liquifaction enzymes. Spartan had significantly higher galactose levels as compared to Red Delicious apples, but changes in galactose in all varieties during 9 months of cold storage were insignificant. Blanching and canning decreased galactose levels, but doubling the thermal processing during canning increased the free galactose concentration detected in plant tissue. An enzymatic liquefaction aid used to prepare apple juice dramatically increased the free galactose content while a clarification aid caused only a slight increase due to its selective action on soluble pectin. These findings provide useful information for dietitians to base diet recommendations for galactosemic patients.     

Total and inorganic arsenic in marketed food and associated health risks for the Catalan (Spain) population

Inorganic arsenic (iAs) is considered to be a human carcinogen. In this paper, total (As) and iAs contents of 215 food products and drinks (i.e., seafood, fruits and vegetables, meat products, oils and fats, rice and rice products, seasonings, and alcoholic drinks) marketed in Catalonia (Spain) were quantified by inductively coupled plasma-mass spectrometry. The analytical method described was used for different food products, obtaining feasible results without the need to couple LC-ICP-MS for iAs. Daily As and iAs intakes for the average adult Catalan consumer were estimated at 354 and 6.1 μg/day/person, respectively, using consumption data from the Catalan Nutrition Survey (ENCAT). The highest As content was found in seafood, contributing 96% of dietary As intake, whereas rice presented the highest iAs values, corresponding to 67% of dietary iAs intake. As cooking process may affect iAs content, boiled rice was evaluated, showing an iAs reduction (up to 86%) when using higher water volumes (30:1 water/rice ratio) than those used in previous studies. This iAs exposure was slightly below the exposure risk range stated by the European Food Safety Authority (0.3-8 μg/kg of body weight/day), although the possibility of a risk to the population with high rice consumption cannot be excluded.     

Volatile constituents in fresh and processed juices from grapefruit and new grapefruit hybrids

Forty-five volatile constituents of juices from grapefruit and grapefruit hybrids were quantified by headspace gas chromatography. The three types of grapefruit juice analyzed include pasteurized juice not from concentrate, reconstituted single strength juice from concentrate, and fresh, unpasteurized juice. Principal component and discriminant analyses were carried out using 48 grapefruit juice samples, and the samples were classified into the three types of juice based on degree of processing. Discriminant analysis was superior to principal component analysis for this purpose. Juices from two recently developed grapefruit hybrids were classified similarly to unpasteurized grapefruit juices from commercial cultivars.     

Source of arsenic in licorice confectionery products

Spanish legislation sets a maximum level for total arsenic (As) in confectionery products at 0.1 microg g(-)(1). The U.S. Food and Drug Administration limitations for glycyrrhizic acid in hard and soft candies are 160 and 31 mg g(-)(1), respectively. Arsenic and glycyrrhizic acid were determined in 22 different confectionery products: 9 throat pearls, 4 hard candies, and 9 soft candies. Arsenic and glycyrrhizic acid were quantified by atomic absorption spectrometry with hydride generation and high-performance liquid chromatography, respectively. Levels of glycyrrhizic acid were always below the maximum limits established by the U.S. FDA; however, the As concentration in seven of nine throat pearls (0.55 +/- 0.15 microg g(-)(1)) were above the Spanish maximum limit. A clear empirical relationship between the arsenic and glycyrrhizic acid concentrations was observed (R (2) = 0.9357), implying that to avoid high levels of potentially toxic arsenic in licorice confections high-quality licorice extract should be used.     

Speciation and monitoring test for inorganic arsenic in white rice flour

A monitoring test for arsenic species in white rice flour was developed and applied to flours made from 20 samples of polished rice collected from locations all over Japan. The arsenic species in white rice flour made from five samples each of four types of rice were analyzed by HPLC-ICP-MS after a heat-assisted aqueous extraction. The total arsenic and major and minor element concentrations in the white rice flours were measured by ICP-MS and ICP-OES after microwave-assisted digestion. 91 ± 1% of the arsenic in the flours was extractable. Concentrations of arsenite [As(III)], arsenate [As(V)], and dimethylarsinic acid (DMAA) were closely positively correlated with the total arsenic concentrations. The total arsenic concentration in flours made from rice collected around Japan was 0.15 ± 0.07 mg kg(-1) (highest, 0.32 mg kg(-1)), which is very low. It was thus confirmed that the white rice flour samples collected in this experiment were not suffered from noticeable As contamination.     

Determination of epsilon-N-pyrrolylnorleucine in fresh food products.

epsilon-N-Pyrrolylnorleucine was determined in different fresh food products to study its presence as a normal component of food proteins. Twenty-two different products were screened: cod, cuttlefish, salmon, sardine, trout, beef, chicken, pork, broad bean, broccoli, chickpea, garlic, green pea, lentil, mushroom, soybean, spinach, sunflower, almond, hazelnut, peanut, and walnut. Foods were homogenized, their proteins were precipitated with trichloroacetic acid and hydrolyzed with 2 N NaOH for 20 h, and the epsilon-N-pyrrolylnorleucine content was determined by capillary electrophoresis. The epsilon-N-pyrrolylnorleucine, which was identified by HPLC/MS in sardine muscle hydrolysate, ranged in the 22 foods analyzed from 0.24 to 6.36 micromol/g. This concentration was correlated with the protein content of the food (r = 0.687, p = 0.00041). In addition, the epsilon-N-pyrrolylnorleucine/lysine ratio was found to be a function of the lipid, iron, and protein contents of the food (r = 0.881, p < 0.0001) and was directly correlated with lipid and iron contents and inversely correlated with the protein content. These results are in agreement with the oxidative stress origin proposed for epsilon-N-pyrrolylnorleucine and suggest that the epsilon-N-pyrrolylnorleucine/lysine ratio is a characteristic of each food. In addition, epsilon-N-pyrrolylnorleucine seemed to be a normal component of many fresh food products, in which it may be acting as a natural antioxidant.     

Occurrence of 6-methoxymellein in fresh and processed carrots and relevant effect of storage and processing

The occurrence of 6-methoxymellein (6-MM) in fresh and conventionally processed carrot products (for a total of 176 samples) marketed in European locations and the effect of Alternaria spp. infection and storage conditions on 6-MM accumulation were investigated. 6-MM was found in 78% of tested samples with levels ranging from 0.02 to 76.00 microg/g, with only 1 of 79 fresh carrots exceeding the "just noticeable difference" level for 6-MM. Storage of carrots at 1 degree C was suitable to maintain low levels of 6-MM for a period of at least 17 weeks. No effect of Alternaria spp. infection was observed on 6-MM occurrence. The fate of 6-MM during carrot juice processing was also investigated by using different enzyme formulations for maceration and blanching procedures. Levels of 6-MM in blanched carrots obtained by boiling water or steam treatment were reduced by 69 or 33%, respectively, as compared to fresh carrots. No decrease in 6-MM levels was observed after maceration with pectinolytic enzyme preparations (Rapidase Carrot Juice and Ultrazym AFP-L). A reduction of 6-MM by 85 or 94% was obtained after the entire cycle of carrot juice processing, depending on the blanching procedure used.     

Presence of 2-furoylmethyl derivatives in hydrolysates of processed tomato products

Acid hydrolysis of Amadori compounds yields the corresponding 2-furoylmethylamino acids (2-FM-AA) that can be analyzed by ion-pair HPLC. The relative proportions of the different 2-FM-AA present in the hydrolysates of tomato products were determined to assess their usefulness as indicators of quality. In the lyophilized tomato samples stored at 50 degrees C and a(w) = 0.44 the formation of 2-FM derivatives of alanine, gamma-aminobutyric acid (GABA), asparagine, aspartic acid, glutamic acid, lysine, serine, and threonine was detected. In commercial tomato products the most abundant 2-FM-AA was 2-FM-GABA (from traces to 26.4 mg/100 g of dry matter) followed by 2-FM-lysine (furosine). Differences in 2-FM-AA contents among samples may be related to processing and storage conditions.     

Gas chromatographic determination of fenvalerate insecticide residues in processed tomato products and by-products

The results of a 5-laboratory collaborative determination of residues of the synthetic pyrethroid insecticide fenvalerate in tomato products are presented. Tomatoes from plants treated in the field at 2-4 day intervals (13 foliar applications) were processed into chopped fresh tomatoes, canned quarters, juice, paste, and the by-product skins plus seeds. Gas chromatographic analysis of the commodities for fenvalerate showed the fresh produce to contain 0.26 ppm, and the skins plus seeds contained 1.9 ppm. Residues were barely detectable in canned peeled quarters and juice, but averaged 0.12 ppm for paste, the concentration product of juice. High residues were associated with the skin content of the product. Five laboratories using modifications of the same analytical technique obtained good collaborative agreement.     

Gas chromatography-mass spectrometry determination of phosphine residues in stored products and processed foods

A gas chromatography-mass spectrometry (GC-MS) method was used for the quantitative confirmation of phosphine residues in stored products and processed foods. An established extraction technique was utilized for the preparation of headspace samples, which were analyzed by GC-MS and gas chromatography-nitrogen-phosphorus detection (GC-NPD). Wheat, oats, maize, white rice, brown rice, cornflakes, tortilla cornchips, groundnuts, and raisins were validated, showing excellent agreement between detectors when spiked at levels equivalent to 0.001 and 0.01 mg/kg phosphine and for samples containing incurred residues. The GC-MS method was reproducible and accurate when compared to the GC-NPD method and allowed five samples to be quantified in a working day. Subambient GC-MS oven temperatures were most suitable for phosphine residues ranging from 0.001 to 0.005 mg/kg, and a GC oven temperature of 100 degrees C was appropriate for residues >0.005 mg/kg. The method was sufficiently robust to be evaluated for other similar commodities as the need arises.     

Compositional characteristics and antioxidant properties of fresh and processed sea cucumber (Cucumaria frondosa)

The antioxidant activity of fresh and rehydrated sea cucumber (Cucumaria frondosa) samples with/without internal organs was evaluated for the first time. In addition, their proximate, amino acid, and fatty acid compositions were examined. Rehydrated sea cucumber samples in distilled water were prepared from oven-dried products. All samples contained 83-90% moisture, but showed a significant difference among groups in their protein and lipid contents. Glutamic acid was the predominant amino acid in sea cucumber, followed by glycine and aspartic acid. Essential amino acids such as leucine and lysine were also present at high levels. The trend for free amino acid was different from that of total amino acids and varied among groups. Lipids in sea cucumber were dominated by eicosapentaenoic acid (EPA, C20:5n-3), ranging from 43.2 to 56.7% of the total fatty acids. Docosahexaenoic acid (DHA, C22:6n-3) was present at a much lower concentration of 2.0-5.8%. All sea cucumber samples exhibited radical scavenging property against 2,2'-azobis(2-aminopropane) dihydrochloride (AAPH) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, with rehydrated samples, especially those with internal organs, possessing higher antioxidant activity than their fresh counterparts. No correlation existed between radical scavenging capacity and total phenolics content, suggesting that other components, in addition to phenolic compounds, contribute to the antioxidant activity of sea cucumber.     

Distribution of protein oxidation products in the proteome of thermally processed milk

During thermal milk processing, severe oxidation can occur, which alters the technological and physiological properties of the milk proteins. Due to differences in composition and physicochemical properties, it can be expected that the particular milk proteins are differently affected by oxidative damage. Therefore, the protein-specific distribution of oxidation products in the heated milk proteome was investigated. Raw and heated milk samples were separated by one-dimensional gel electrophoresis. Protein oxidation was visualized by Western blot after derivatization of protein carbonyls with 2,4-dinitrophenylhydrazine. Thus, α-lactalbumin displayed enhanced oxidation compared to β-lactoglobulin, despite its lower concentration in milk. Highly selective oxidation was detected for a previously unassigned minor milk protein. The protein was identified by its peptide mass fingerprint as a variant of α(S1)-casein (α(S1)-casein*). Similar oxidation patterns were observed in several commercial milk products.     

Processing and storage effects on the ellagitannin composition of processed blackberry products

Changes in blackberry ellagitannin composition in response to juicing (clarified and nonclarified), pureeing, canning (in water or syrup), and freezing as well as changes in processed products during 6 months of storage were investigated. Canning, pureeing, and freezing had little effect on ellagitannins, but processing berries into nonclarified and clarified juices resulted in total ellagitannin losses of 70 and 82%, respectively, due to removal of ellagitannin-rich seeds in the presscake. Minimal changes in total ellagitannin content were observed during storage of thermally processed products, but compositional changes indicative of ellagitannin depolymerization were apparent. The ellagitannin content and composition of frozen berries remained stable over 6 months of storage. Ellagitannins are well retained in canned, pureed, and frozen blackberries, but methods are needed to prevent losses during juice processing and/or exploit the ellagitannin-rich coproducts.     

Determination and distribution of 6-methoxymellein in fresh and processed carrot puree by a rapid spectrophotometric assay.

Isocoumarin or 6-methoxymellein (6-MM) was extracted from carrot tissue using alkali saponification to solubilize the lactone portion of its structure into an aqueous phase. Acidification and subsequent organic solvent extraction allowed isolates to be quantified and verified as 6-MM by spectrophotometric determination. 6-Methoxymellein was analyzed in carrot cross sections, as a function of depth and before and after thermal processing. A natural propensity for 6-MM accumulation was observed in root tip sections exposed to ethylene, and levels increased as a result of wounding. Consecutive layer peeling demonstrated that small-diameter roots accumulated greater amounts of 6-MM in periderm tissue compared to large roots. Processing carrots into a puree resulted in 10-25% greater extraction of 6-MM than grinding fresh carrot samples, whereas steam-cooked and thermally processed purees had 15% greater extraction than unheated purees. This analytical technique will allow carrot processors to accurately estimate raw and processed products for the bitter compound 6-MM.     

Cancer risk to Japanese population from the consumption of inorganic arsenic in cooked hijiki

The cancer risk posed by inorganic arsenic (iAs) ingestion via the consumption of hijiki seaweed, a common Japanese food item known to accumulate pentavalent arsenic, was estimated. Fourteen households were asked to supply three portions of cooked hijiki (boiled and fried with vegetables and fried bean curd, etc.), as usually cooked and served per person in each household. The monthly consumption frequency of cooked hijiki was assessed by questionnaire: it was typically two to three times a month in most households. The mean daily consumption of cooked hijiki was estimated to be 6.5 g/day (range = 1.1-14 g/day, median = 5.5 g/day) by multiplying one serving quantity (grams) by the monthly frequency of consumption. The concentration of iAs [As(III) + As(V)] in the cooked hijiki was determined after homogenization, freeze-drying, 0.07 mol/L HCl extraction, and high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICPMS). The concentration of iAs ranged from 0.4 to 2.8 mg/kg (wet weight basis) in the cooked hijiki, and iAs intake from cooked hijiki was calculated to be 0.0005-0.023 mg/day. On the basis of these data and the oral slope factor [1.5E0 (mg/kg/day) (-1)] reported by the U.S. EPA for iAs, the mean skin cancer risk through cooked hijiki consumption was calculated to be 2.4 x 10(-4) (range = 1.6 x 10(-6) -7.0 x 10(-4)), which exceeded the acceptable level of 10(-5). Taking the risk of other cancers (bladder, lung, etc.) into consideration, the contribution to cancer occurrence through the consumption of hijiki seaweed may not be negligible.     

Lipophilic toxins analyzed by liquid chromatography-mass spectrometry and comparison with mouse bioassay in fresh, frozen, and processed molluscs

The search for alternative methods to the mouse bioassay (MBA) has intensified over recent years. The present work analyzes seven different species of shellfish (clams, small scallops, small clams, mussels, oysters, cockles, and edible whelks) in fresh, frozen boiled, and canned presentations using liquid chromatography-mass spectrometry (LC-MS/MS), and the results are compared with the same samples analyzed through MBA. The toxins studied were OA, DTX1, DTX2, YTX, PTX2, and AZA1, which are legislated in the EU, and SPX1, which is not regulated yet. Consistent results between LC-MS/MS and MBA were found in 69% of the samples, whereas 26% of MBA showed "false-positive" results with respect to the toxins analyzed. No "false negatives" were observed. The possibility of LC-MS/MS as an alternative or complementary technique to MBA is discussed.     

Flavonoid content in fresh, home-processed, and light-exposed onions and in dehydrated commercial onion products

Onion plants synthesize flavonoids as protection against damage by UV radiation and by intracellular hydrogen peroxide. Because flavonoids also exhibit health-promoting effects in humans, a need exists to measure their content in onions and in processed onion products. To contribute to the knowledge about the levels of onion flavonoids, HPLC and LC-MS were used to measure levels of seven quercetin and isorhamnetin glucosides in four Korean commercial onion bulb varieties and their distribution within the onion, in scales of field-grown onions exposed to home processing or to fluorescent light and in 16 commercial dehydrated onion products sold in the United States. Small onions had higher flavonoid content per kilogram than large ones. There was a graduated decrease in the distribution of the flavonoids across an onion bulb from the first (outside) to the seventh (innermost) scale. Commercial, dehydrated onion products contained low amounts or no flavonoids. Losses of onion flavonoids subjected to "cooking" (in percent) ranged as follows: frying, 33; sauteing, 21; boiling, 14-20; steaming, 14; microwaving, 4; baking, 0. Exposure to fluorescent light for 24 and 48 h induced time-dependent increases in the flavonoid content. The results extend the knowledge about the distribution of flavonoids in fresh and processed onions.     

Determination of arsenic and selenium in whole fish by continuous-flow hydride generation atomic absorption spectrophotometry

A combined wet chemical and dry ash digestion and use of a continuous-flow hydride generator coupled with a flame-heated quartz cell enabled the simple, precise, and highly automated atomic absorption determination of arsenic and selenium in tissues of whole fish. Percent relative standard deviation averaged 4% for each element; method detection limits (micrograms/g dry wt) were about 0.06 for arsenic and 0.04 for selenium. Digestion of samples proceeded with little operator attention and without perchloric acid. Analysis for arsenic as As(V) simplified sample preparation but care had to be exercised to avoid interferences from high concentrations of selenium.