The Presence of Bioactive Compounds in European Eel (Anguilla anguilla) Skin: A Comparative Study with Edible Tissue.

The presence of bioactive compounds in European eel (Anguilla anguilla) skin was studied. Proximate and lipid class compositions and analysis of the fatty acid (FA) profile (individual FAs; FA groups, i.e., saturated, monounsaturated, and polyunsaturated; FA ratios, i.e., polyunsaturated/saturated, ω3/ω6) were determined and compared to the composition of the eel muscle. As a result, higher (p < 0.05) levels of proteins (271.6 g·kg-1), lipids (38.0 g·kg-1), ash (27.7 g·kg-1), and ω6 FAs were observed in the skin tissue. Contrary, the muscle tissue showed higher (p < 0.05) moisture, ω3 FA, and ω3/ω6 ratio values. Regarding lipid classes, a higher (p < 0.05) proportion of phospholipids (111.1 g·kg-1 lipids), free sterols (104.7 g·kg-1 lipids), α-tocopherol (274.0 mg·kg-1 lipids), and free FAs (43.6 g·kg-1 lipids) was observed in the skin tissue. No differences (p > 0.05) between both tissues could be detected for triacylglycerol and FA group (saturated, monounsaturated, and polyunsaturated) values and for the polyunsaturated/saturated FA ratio. It is concluded that European eel skin, a by-product resulting from commercial processing, can be considered a valuable source for the food and pharmaceutical industries by providing value-added constituents such as proteins, lipids, ω3 FAs, phospholipids, and α-tocopherol.

Physicochemical, Sensory, and Nutritional Properties of Foods Affected by Processing and Storage Series II.

Food processing has several different purposes [...].

Antioxidant Activity, Total Phenolic Content and Total Flavonoid Content in Sweet Chestnut (Castanea sativa Mill.) Cultivars Grown in Northwest Spain under Different Environmental Conditions.

The sweet chestnut fruit has always had great importance in the southern European countries. Chestnut production is an important source of income and a crop of high environmental value thanks to its role in soil protection. It is also a good food with enormous potential for various aspects of health because of its nutritional qualities. The quality of sweet chestnuts is affected by various factors, such as climatic conditions and cultivation inputs. It is very important to recognize the impacts of climate on chestnut fruits, to improve our current understanding of climate-chestnut interconnections. The current study investigated and compared the antioxidant activity and the total phenolic and flavonoid contents of different cultivars of chestnuts grown in different geographic areas of northwest Spain. The results obtained with three antioxidant capability assays (DPPH, ABTS and FRAP assays) were highly correlated. All the samples had high antioxidant capacity and high total phenolic and total flavonoid contents, which depended both on cultivar and growth region. Ventura variety, harvested in the coldest environments, presented the highest values of antioxidant activity (IC50DPPH = 34.5 g/L), total phenolic content (131.84 mg equivalent of gallic acid/100 g FW) and total flavonoids (7.77 mg eq. catechin/100 g). The variations in the antioxidant capacity, total phenolic and total flavonoid contents of different cultivars, and their associations with climatic environmental factors, revealed the significant impacts of these factors on the synthesis of specialized metabolites and on the nutraceutical potential of chestnuts. The results can provide valuable information for selection of the cultivar and the cultivation conditions of the chestnut, in order to obtain chestnuts with high-quality bioactive characteristics.

Deep Eutectic Solvents as a Green Tool for the Extraction of Bioactive Phenolic Compounds from Avocado Peels.

Avocado peels are the main agro-industrial residue generated during the avocado processing, being a rich source of bioactive compounds like phenolic compounds. The growing demand for more sustainable processes requires the development of new and effective methods for extracting bioactive compounds from industrial waste. Deep eutectic solvents (DESs) are a new sustainable alternative to toxic organic solvents due to their non-toxicity and biocompatibility. In this study, five selected DESs were applied for the extraction of bioactive phenolic compounds from avocado peels. The extraction efficiency was evaluated by measuring the total phenolics and flavonoids content. The best extraction results were obtained with choline chloride-acetic acid and -lactic acid (92.03 ± 2.11 mg GAE/g DAP in TPC and 186.01 ± 3.27 mg RE/g DAP); however, all tested DESs show better extraction efficiency than ethanol. All the obtained NADES extracts have high antioxidant activity (FRAP: 72.5-121.1 mg TE/g; TAC: 90.0-126.1 mg AAE/g). The synthesized DESs and avocado peels DES extracts had activity against all tested bacteria (Staphylococcus aureus, Streptococcus dysgalactiae, Escherichia coli and Pseudomonas putida), and the extracts prepared with choline chloride-acetic acid and -lactic acid have the highest antibacterial activity against all microorganisms. These results, coupled with the non-toxic, biodegradable, low-cost, and environmentally friendly characteristics of DESs, provide strong evidence that DESs represent an effective alternative to organic solvents for the recovery of phenolic bioactive compounds from agro-industrial wastes.

Impact of the Filling Medium on the Colour and Sensory Characteristics of Canned European Eels (Anguilla anguilla L.).

The different vegetable oils used in canned fish as a filling medium have a preserving effect and contribute to the palatability of the product. In this study, the colour of European eels and the filling medium (sunflower oil, olive oil or spicy olive oil) was measured at different steps of the canning process. The sensorial characteristics of canned eels packed in the different oils were also evaluated. Colour scores (CieLab values) were higher in canned eels packed in sunflower and spicy olive oil than in canned eels packed in olive oil. The changes in colour parameters depended on the type of oil, the stage of the process and the storage time. Colour changes in canned eels packed in olive oil were highest during the sterilization process. Spicy olive oil was the filling medium in which the colour change was greatest, probably due to the migration of some of the spice components into the oil. Organoleptic properties were directly related to the type of oil used as the filling medium. The canned eels packed in sunflower oil were those awarded the highest scores in consumer tests, although the preferences varied depending on the age and gender of the consumers.

Physicochemical, Sensory and Nutritional Properties of Foods Affected by Processing and Storage.

Due to their chemical composition and physicochemical characteristics, most foods are very perishable and are easily altered by physical, chemical and biological agents [...].

Oxidative Stability and Antioxidant Activity in Canned Eels: Effect of Processing and Filling Medium.

The effect of canning and the use of different filling media (sunflower oil, olive oil, and spiced olive oil) on oxidation parameters (acidity, peroxide value (PV), and thiobarbituric acid reactive substances (TBARS) index), antioxidant capacity, and total phenol and vitamin E contents in eels was studied. A preliminary frying treatment caused a decrease in titratable acidity and an increase in TBARS, antioxidant capacity, and vitamin E in the eel muscle. During sterilization, TBARS also increased significantly. The magnitude of the changes depended on the filling medium. Storage also had a significant effect on oxidation parameters in eel muscle and in filling media. After one year of storage, the sunflower oil and canned eels packed in this oil presented higher antioxidant capacity and vitamin E content than olive oil, spiced olive oil, or canned eels packed in these oils. However, the total phenol contents were higher when olive oil or spiced olive oil were used as filling media. Despite the losses, the results show that the canning process and subsequent storage preserved a great part of the antioxidant capacity and vitamin E content of the filling medium, which is of interest to the consumer. Both sunflower oil and olive oil as filling media are of great nutritional interest.

Free Amino Acids and Biogenic Amines in Canned European Eels: Influence of Processing Step, Filling Medium and Storage Time.

This study evaluated the effects of the canning process and different filling media on the free amino acid and biogenic amine contents of eels. The main free amino acids were histidine, taurine and arginine, which constituted 72% of the free amino acids in raw eels. All steps in the canning process significantly altered the free amino acid content of eels, relative to raw samples. The changes were influenced by the step, the composition of the frying or filling medium and the storage time. The biogenic amine contents were very low in all samples. Histamine was not detected in either raw eels or canned eels. The highest values were obtained for 2-phenylethylamine. The step of the canning process, the composition of the frying or filling medium and storage time also determined the changes in the biogenic amine contents. The biogenic amines indices were low, indicating the good quality of canned eels.

Impact of processing and storage on the nutritional and sensory properties and bioactive components of Brassica spp. A review.

Brassica spp. are excellent sources of bioactive compounds. These vegetables are usually processed in the home, or by catering and food service industries, on the basis of convenience and taste preference. Shelf-life of these seasonal, perishable vegetables can be extended by preservation methods (e.g. freezing and canning), which usually involve blanching. Cooking, blanching, freezing and canning alter the physical and chemical characteristics of Brassica, and only some of the changes are desirable. We have reviewed the results of a large number of studies that assessed the effects of different treatments and storage conditions on various quality parameters in Brassica. These effects are important in relation to nutritional value, health benefits and attractiveness of the vegetables. The findings vary considerably for each bioactive component, depending on the treatments, conditions and matrices. Optimization of processing and storage conditions is, therefore, important to maximize the intake of beneficial compounds contained in Brassica spp.

Effects of different cooking methods on the antioxidant capacity and flavonoid, organic acid and mineral contents of Galega Kale (Brassica oleracea var. acephala cv. Galega).

Brassica spp. are good sources of bioactive substances, which are known to have beneficial health effects. The objective of this work was to evaluate the effect of different cooking methods (boiling, steaming, microwaving, pressure cooking and vacuum cooking) on the antioxidant capacity and on the flavonoid, organic acid and mineral contents of Galega kale. Results indicate that this vegetable has a high antioxidant capacity and high contents of total flavonoids, organic acids, and minerals such as potassium and calcium. All of the cooking methods yielded losses of antioxidant capacity and of total flavonoids, organic acids and minerals, relative to the contents in fresh kale. Steaming proved to be the best method of preserving the antioxidant capacity and bioactive compounds. Although cooking did not cause large losses of oxalic acid, the resulting oxalate:calcium ratio was rather low (<2). The present data demonstrate that the different cooking methods have different effects on the bioactive compounds in kale, and that it is important the optimisation of such methods in order to minimise losses of the nutritional properties.

Oxidation of edible animal fats. Comparison of the performance of different quantification methods and of a proposed new semi-objective colour scale-based method.

The agreement among the results determined for the main parameters used in the evaluation of the fat auto-oxidation was investigated in animal fats (butter fat, subcutaneous pig back-fat and subcutaneous ham fat). Also, graduated colour scales representing the colour change during storage/ripening were developed for the three types of fat, and the values read in these scales were correlated with the values observed for the different parameters indicating fat oxidation. In general good correlation among the values of the different parameters was observed (e.g. TBA value correlated with the peroxide value: r=0.466 for butter and r=0.898 for back-fat). A reasonable correlation was observed between the values read in the developed colour scales and the values for the other parameters determined (e.g. values of r=0.320 and r=0.793 with peroxide value for butter and back-fat, respectively, and of r=0.767 and r=0.498 with TBA value for back-fat and ham fat, respectively).

Antioxidant activity of sugar molasses, including protective effect against DNA oxidative damage.

Extracts were obtained from molasses, a byproduct of the sugar industry, via a number of chromatographic steps. Their antioxidant capacity was studied, including the inhibitory effect upon DNA oxidative damage; the phenolic compound profile thereof was ascertained as well. Two extracts exhibited significant antioxidant features, expressed by their capacity to decolorize ABTS radical cation and to scavenge hydroxyl free radicals (via deoxyribose assay). Those 2 extracts also brought about protection against induced DNA oxidative damage (via decreasing DNA scission, as assessed by electrophoresis). The phenolic compounds syringic acid, p-hydroxybenzoic acid, vanillic acid, p-hydroxybenzaldehyde, and ferulic acid were positively identified and quantified.

The composition of Arnoia peppers (Capsicum annuum L.) at different stages of maturity.

'Arnoia' peppers (Capsicum annuum L. var. annuum cv. Arnoia) are cultivated in areas surrounding the Arnoia River, in Galicia (northwest Spain). Some physical and chemical changes associated with maturation and storage conditions have been reported. Changes in gross composition, the main physico-chemical parameters and mineral composition were evaluated in peppers collected directly from plants and at two different states of maturity (green and red fruits), and in commercially available peppers (green fruits). The total soluble solid content and titratable acidity increased significantly during ripening. The fat, ash and protein contents were generally significantly higher in the red pepper than in the green peppers. The total ascorbic acid in red peppers was 27% higher than that of green peppers. The vitamin C content of commercially available green peppers was up to 39% lower than in the freshly picked peppers. Potassium was the most abundant mineral in green and red peppers. Green peppers purchased in the supermarket contained higher amounts of calcium and sodium than the freshly picked peppers. The levels of zinc, manganese and copper were similar in all of the different samples.

Effect of environmental parameters on growth kinetics of Bacillus cereus (ATCC 7004) after mild heat treatment.

The influence of temperature (10 to 50 degrees C), initial pH (4.0 to 6.0) and sodium chloride concentration (0.5 to 3.0%) on the growth in nutrient broth and in meat extract of Bacillus cereus after mild heat treatment (90 degrees C--10 min) was determined. B. cereus spores survived after heating and they were able to germinate and grow in both media when post-treatment conditions were favourable. Heated B. cereus did not grow at 10 and 50 degrees C or in a medium with pH 4.0. Decreasing pH values and increasing levels of sodium chloride decreased growth rate and increased the lag phase of B. cereus. pH 4.5 was unable to prevent the growth of heated spores in a meat substrate with 0.5% NaCl at 12 degrees C. The combination of pH /=1.0% and temperatures /=60 degrees C could control heated B. cereus ATCC 7004 growth.

Biogenic amine content during the manufacture of dry-cured lacón, a Spanish traditional meat product: Effect of some additives.

The content of nine biogenic amines (agmatine, tryptamine, 2-phenylethylamine, putrescine, cadaverine, histamine, tyramine, spermidine and spermine) was determined throughout the manufacture of dry-cured lacón, a traditional dry-salted and ripened meat product made in the north-west of Spain from the fore leg of the pig following a similar process to that of dry-cured ham. The effect of the use of additives (glucose, sodium nitrite, sodium nitrate, sodium ascorbate and sodium citrate) on the biogenic amine content during manufacture was also studied. Tryptamine and spermine were the main biogenic amines in fresh meat, while tryptamine and cadaverine were the most abundant at the end of the manufacturing process. During ripening the total amine content increased significantly (P<0.05) in the batches made both without and with additives. The use of additives significantly (P<0.05) increased the total amine content and the content of tryptamine, tyramine and histamine. The total biogenic amine content at the end of the manufacturing process was low as expected for a product in which there is little active microbial metabolism during manufacture.

The effects of ripening stage and processing systems on vitamin C content in sweet peppers (Capsicum annuum L.).

Morrón pepper of 'Fresno de la Vega' (Capsicum annuum L.) is a big sweet variety cultivated in the province of León (northwestern Spain). Changes in vitamin C content of this variety of pepper as a function of ripeness, storage and different preservation systems were studied. The ascorbic acid content increases in peppers as they ripen. For green mature, breaker and red peppers values of 107.3+/-1.84, 129.6+/-3.11 and 154.3+/-7.56 mg/100 g edible portion were found. The vitamin C content for green mature and breaker peppers stored at room temperature (20 degrees C) increased up to 10 days of storage, reaching similar values as those obtained for red peppers direct from the plant. However, stored red ripe peppers showed a significant loss in vitamin C content, around 25%. Refrigeration at 4 degrees C for up to 20 days did not change the ascorbic acid content, except for red peppers, which showed losses around 15%. The ascorbic acid content was altered in response to the preservation procedures assayed. Reductions of 12% and 20-25% during the water blanching and canning process, respectively, were observed. Ascorbic acid retention during freezing was 60%, increasing when the product was previously blanched (87%). Dehydration of peppers resulted in an 88% decrease in ascorbic acid content, whereas freeze-drying did not cause significant losses.