Bárbara Teixeira

Chemical composition and bioactivity of different oregano (Origanum vulgare) extracts and essential oil

BACKGROUND There is a growing interest in industry to replace synthetic chemicals by natural products with bioactive properties. Aromatic plants are excellent sources of bioactive compounds that can be extracted using several processes. As far as oregano is concerned, studies are lacking addressing the effect of extraction processes in bioactivity of extracts. This study aimed to characterise the in vitro antioxidant and antibacterial properties of oregano (Origanum vulgare) essential oil and extracts (in hot and cold water, and ethanol), and the chemical composition of its essential oil. RESULTS The major components of oregano essential oil were carvacrol, β-fenchyl alcohol, thymol, and γ-terpinene. Hot water extract had the strongest antioxidant properties and the highest phenolic content. All extracts were ineffective in inhibiting the growth of the seven tested bacteria. In contrast, the essential oil inhibited the growth of all bacteria, causing greater reductions on both Listeria strains (L. monocytogenes and L. innocua). CONCLUSION O. vulgare extracts and essential oil from Portuguese origin are strong candidates to replace synthetic chemicals used by the industry.

Antioxidant and antimicrobial activity of Satureja montana L. extracts

BACKGROUND This study aimed to evaluate the antioxidant and antimicrobial activity of extracts (aqueous, ethanolic and essential oil) from Satureja montana and to characterise the chemical composition of its essential oil. RESULTS Satureja montana L. essential oil had relatively high antimicrobial activities against the seven species of bacteria tested. In contrast, aqueous extracts did not reveal antibacterial activity, and the ethanol extract was not effective against Salmonella typhimurium. The major volatile constituents of the essential oil were carvacrol (306 g L(-1)), thymol (141 g L(-1)), and carvacrol methyl ether (63 g L(-1)). The strongest antioxidant capacity was obtained with the hot water extracts of S. montana, whereas the plant essential oil revealed the highest phenolic content. CONCLUSION The findings indicate that the bioactive extracts of S. montana have strong potential for use as natural antimicrobials and antioxidants in the preservation of processed food.

Antioxidant and antibacterial activity of essential oil and extracts of bay laurel Laurus nobilis Linnaeus (Lauraceae) from Portugal

Laurus nobilis L. is an aromatic plant frequently used as a spice in Mediterranean cookery and as a traditional medicine for the treatment of several infectious diseases. The aim of this study was to characterise the antibacterial and antioxidant activities of bay laurel essential oil (EO), ethanolic extract (EE) and hot/cold aqueous extract (AE). The major components detected in bay laurel EO were eucalyptol (27.2%), α-terpinenyl acetate (10.2%), linalool (8.4%), methyleugenol (5.4%), sabinene (4.0%) and carvacrol (3.2%). The EO exhibited strong antibacterial activity against all tested foodborne spoilage and pathogenic bacteria, whereas this activity was less pronounced or even nonexistent in the EE and AE. In contrast, EO exhibited low antioxidant activity compared to extracts (EX), and among the EX, the hot AE revealed the highest antioxidant ability. The results show that bay laurel EO and its EX have potential as natural alternatives to synthetic food preservatives, in order to enhance food safety and increase food shelf life.

Effect of Season on the Chemical Composition and Nutritional Quality of the Edible Crab Cancer pagurus

Cancer pagurus is most appreciated in southern Europe for its muscle and brown meat content. In Portugal, consumption occurs mostly in summer and at Christmas. In this study the seasonal nutritional quality of edible tissues of female and male C. pagurus was determined. Tissue composition was affected by season and sex. All tissues had a well-balanced essential amino acid composition. Muscle and gonads of females had n-3/n-6 ratios in the range of the usual recommended values, and all tissues had PUFA/SFA above the recommended level. Autumn was the season with the highest brown meat yield, total essential amino acids (muscle), taurine (all tissues), EPA (male gonads), and n-3/n-6 ratio (gonads). However, it was also the season with the highest fat content and cholesterol concentration in ovaries. Therefore, people with restricted diets should moderate the consumption of ovaries in autumn. The remaining tissues pose no risks with respect to their proximate chemical composition.

Nutritional quality of the edible tissues of European lobster Homarus gammarus and American lobster Homarus americanus.

The clawed lobsters Homarus gammarus and Homarus americanus are high-priced and appreciated food items in southern Europe. From a nutritional point of view there is still limited information on the chemical composition of edible tissues (muscle, hepatopancreas, and gonads) of both species. Therefore, the aims of the present work were to study the proximate chemical composition, energy, fatty acid and amino acid profiles, and cholesterol content in each edible tissue of both species and to evaluate their nutritional quality. Differences were observed between tissues, sexes, and species. Muscle and gonads were rich in protein, whereas hepatopancreas had high fat, cholesterol, and energy contents. All edible tissues were valuable sources of essential amino acids. Contrary to the common belief that shellfish consumption should be reduced in a low-fat and -cholesterol diet, all edible tissues of clawed lobsters have a nutritious value perfectly compatible with nutritious and healthy diets.

Changes of Enzymes Activity and Protein Profiles Caused by High-Pressure Processing in Sea Bass (Dicentrarchus labrax) Fillets

High-pressure processing (HPP) is a technology of growing interest for food preservation, due to its ability to control the activity of degradative enzymes. The effect of three variables (pressure levels of 100, 250, and 400 MPa; pressure holding times of 0, 5, 15, and 30 min; and pressurization rates of 8 and 14 MPa/s) on the activity of the enzymes acid phosphatase, cathepsins (B and D), lipase, and calpains was studied using sea bass fillets as a case study model. Additionally, the effect of HPP on sarcoplasmic proteins was studied by SDS-PAGE and isoelectric focusing electrophoreses. The increase in pressure level and holding time decreased the protein concentration in sarcoplasmic extracts, and also the activity of calpains. As compared to nontreated samples, acid phosphatase activity was lower at 400 MPa, and for cathepsin D lower activities were observed at 100 and 400 MPa. The increase in pressurization rate increased the activity of cathepsin D, lipase, and calpains, although it was not always significant. In contrast, cathepsin B and lipase activities were less affected by HPP treatments. Electrophoresis separation of sarcoplasmic proteins showed that the intensity of many protein bands changed mainly due to pressure level and holding time. The results of this study suggest that HPP causes lysosomes disruption and also denaturation, aggregation, and fragmentation of sarcoplasmic proteins, and this evidence might be related to the decrease in enzymes activity especially at 400 MPa. In conclusion, HPP can be a potential tool to control the activity of degradative enzymes, which might prevent the softening of sea bass muscle due to autolytic reactions.

Influence of Season and Sex on the Contents of Minerals and Trace Elements in Brown Crab (Cancer pagurus, Linnaeus, 1758)

Cancer pagurus is much appreciated in Southern Europe, where the muscle, hepatopancreas, and gonads are consumed regularly with peaks in summer and December. The elemental contents of C. pagurus edible tissues were analyzed in this study during the four seasons. Results indicate that the content varied with tissue, season, and sex. The hepatopancreas had more S, Cl, Ca, Br, Sr, Fe, Cu, Cd, and Pb, the gonads had a higher concentration of Na, and the muscle was richer in Zn. Autumn and winter corresponded to a high Mg, S, Cl, K, Ca, Fe, and Zn content in both the muscle and hepatopancreas. Female gonads had more Fe, Zn, As, and Se than males but less Ca, Cl, Br, and Sr. Regarding toxic elements for human consumption, the levels of As, Hg, and Pb found in all edible tissues pose minimal risks to consumers. However, Cd concentration in the hepatopancreas was always above the action limit. Therefore, we recommend moderate hepatopancreas consumption.

Control of abusive water addition to Octopus vulgaris with non‐destructive methods

BACKGROUND Abusive water addition to octopus has evidenced the need for quick non-destructive methods for product qualification in the industry and control of fresh commercial products in markets. Electric conductivity (EC)/pH and dielectric property measurements were selected to detect water uptake in octopus. RESULTS A significant EC decrease was determined after soaking octopus in freshwater for 4 h. EC reflected the water uptake of octopus and the correspondent concentration decrease of available ions in the interstitial fluid. Significant correlations were determined between octopus water uptake, EC (R = -0.940) and moisture/protein (M/P) ratio (R = 0.923) changes. Seasonal and spatial variation in proximate composition did not introduce any uncertainty in EC discrimination of freshwater tampering. Immersion in 5 g L-1 sodium tripolyphosphate (STPP) increased EC to a value similar to control octopus. EC false negatives resulting from the use of additives (STPP and citric acid) were eliminated with the additional determination of pH. Octopus soaked in freshwater, STPP and citric acid can also be clearly discriminated from untreated samples (control) and also from frozen (thawed) ones using the dielectric properties. No significant differences in the dielectric property scores were found between octopus sizes or geographical locations. CONCLUSION Simultaneous EC/pH or dielectric property measurements can be used in a handheld device for non-destructive water addition detection in octopus. M/P ratio can be used as a reference destructive method.

Phytochelatins and monothiols in salt marsh plants and their relation with metal tolerance

Phytochelatins (PCs) and monothiols and their relation with trace element concentrations were studied in three plant species from two Portuguese salt marshes. Belowground tissues showed always higher element concentrations, while enhanced values of monothiols were found in aboveground biomass. Glutathione was usually the most abundant monothiol. The concentration of total PCs was higher in leaves or stems than in roots of Halimione portulacoides and Sarcocornia perennis, while in Spartina maritima the highest concentrations were reported in large roots. PC2 was synthesized by all tissues and species and was higher in large roots of S. maritima. PC4 and PC5 were in high levels in small roots of S. maritima. PC2 was positively correlated with As, Zn and Pb. Although being the first evidence of PCs and monothiols in these species under natural conditions, our results do not point to a simple relationship with elements concentrations, suggesting a complex mechanism involved.

Bay Laurel ( Laurus nobilis ) Oils

Abstract Bay laurel (Laurus nobilis) essential oil (EO) has been recognized to possess many interesting properties (e.g., antiseptic, antidiarrheal, antimycotic, antimicrobial, antiinflammatory, antioxidant, and anticarcinogenic) that have wide potential applications in many fields, including health and food. This chapter aims to revise the information available about the composition and potential food applications of bay laurel EO. So far, the wide application of bay laurel EO in industry is mostly performed in aromatherapy, massage therapy, and cosmetics. Scientific research has assessed its potential application in the food industry as well as several limitations that still need to be overcome.