Ana Belen Martin-Diana

Characterization of Phenolic Composition in Lamiaceae Spices by LC-ESI-MS/MS

A total of 38 phenolic compounds in the solid/liquid extracts of five Lamiaceae spices, rosemary, oregano, sage, basil, and thyme, were identified in the present study using LC-ESI-MS/MS. These compounds were distributed in four major categories, namely, hydroxycinnamic acid derivatives, hydroxybenzoic acid derivatives, flavonoids, and phenolic terpenes. Among them, the category of flavonoids was the largest, with 17 compounds. Identification of the phenolic compounds was carried out by comparing retention times and mass spectra with those of authentic standards. If standards were unavailable, phenolic compounds were identified on the basis of accurate mass of pseudomolecular [M - H](-) ions and tandem mass spectrometry (MS/MS) data. The results of accurate mass measurements fit well with the elemental composition of the compounds. The diagnostic fragmentation patterns of the compounds during collision-induced dissociation (CID) elucidated the structural information of the compounds analyzed.

Optimization of Ultrasound Assisted Extraction of Antioxidant Compounds from Marjoram (Origanum majorana L.) Using Response Surface Methodology

The present study optimized the ultrasound assisted extraction (UAE) conditions to maximize the antioxidant activity [Ferric ion Reducing Antioxidant Power (FRAP)], total phenol content (TP) and content of individual polyphenols of extracts from marjoram. Optimal conditions with regard to amplitude of sonication (24.4-61.0 μm) and extraction temperature (15-35 °C) and extraction time (5-15 min) were identified using response surface methodology (RSM). The results showed that the combined treatment conditions of 61 μm, 35 °C and 15 min were optimal for maximizing TP, FRAP, rosmarinic acid, luteolin-7-O-glucoside, apigenin-7-O-glucoside, caffeic acid, carnosic acid and carnosol values of the extracts. The predicted values from the developed quadratic polynomial equation were in close agreement with the actual experimental values with low average mean deviations (E%) ranging from 0.45% to 1.55%. The extraction yields of the optimal UAE were significantly (p < 0.05) higher than solid/liquid extracts. Predicted models were highly significant (p < 0.05) for all the parameters studied with high regression coefficients (R(2)) ranging from 0.58 to 0.989.

Effect of Heat Shock on Browning-Related Enzymes in Minimally Processed Iceberg Lettuce and Crude Extracts

The effects of heat shock on PPO and POD activity in minimally processed Iceberg lettuce was examined during storage (10 days). The results were compared with the effect of temperature on crude extracts of these enzymes (in vitro analysis). Fresh-cut lettuce washed at 50 °C showed significantly lower PPO and POD activity throughout storage than lettuce washed at 4 °C and 25 °C. These results were consistent with a sensory analysis in which the panellists found the lowest browning scores in those samples treated at 50 °C. When PPO and POD were analysed in vitro, the samples treated at 50 °C showed a rapid loss of POD activity and a similar but slower loss of PPO activity in all tissues, while incubation at 4 °C and 25 °C showed no significant loss of activity. While heat shock did not lead to significant loss of activity it did repress the synthesis of PPO and POD during storage.

Comparison between gelatines extracted from mackerel and blue whiting bones after different pre-treatments.

Gelatines were extracted from mackerel and blue whiting bones after chemical or enzymatic pre-treatments and their functional properties (solubility, foaming and emulsifying properties) were analysed. The pre-treatment significantly (p<0.05) affected the composition and the functional properties of the extracted gelatines. The amino acid analyses showed that chemically pre-treated bone gelatines had higher imino acids (proline and hydroxyproline) contents compared to those extracted after the enzymatic pre-treatment, for both fish species. It was observed that all gelatines had higher solubility at low pH with a maximum value observed at pH 2. A significant effect of ionic strength was observed. Increasing the NaCl concentration to more than 1% resulted in a significant decrease of the solubility. Mackerel bone gelatines showed lower foaming capacity (FC) and higher foaming stability (FS) than blue whiting bone gelatines. Increasing the concentration of gelatine decreased the emulsifying activity index (EAI) but increased the stability index (ESI). The use of enzymes in the pre-treatment process gave gelatines with significantly (p<0.05) higher EAI and ESI.

Structure elucidation of ACE-inhibitory and antithrombotic peptides isolated from mackerel skin gelatine hydrolysates

BACKGROUND The fish-processing industry generates significant amounts of waste and by-products that are usually discarded. This study investigated the preparation of bioactive gelatine peptides from fish skin. Gelatine was extracted from mackerel (Scomber scombrus) skin and hydrolysed by pepsin for 1, 2, 6 and 24 h. All hydrolysates were screened for antioxidant, ACE-inhibitory and antithrombotic activities. RESULTS Gelatine peptides obtained after 24 h of hydrolysis exhibited the highest antioxidant activity (DPPH reduction ∼80%, FRAP ∼130 µmol Trolox equivalent L(-1) ). These hydrolysates had high ACE-inhibitory activity (>70%) and were able to significantly (P < 0.05) inhibit platelet aggregation by about 30%, corresponding to moderate antithrombotic activity. CONCLUSION The bioactive properties were mainly due to the presence of low-molecular-weight peptides of 337 and 423 Da.

Application of response surface methodology to optimize pressurized liquid extraction of antioxidant compounds from sage (Salvia officinalis L.), basil (Ocimum basilicum L.) and thyme (Thymus vulgaris L.)

The present study optimized pressurized liquid extraction (PLE) conditions using Dionex ASE® 200, USA to maximize the antioxidant activity [Ferric ion Reducing Antioxidant Power (FRAP)] and total polyphenol content (TP) of the extracts from three spices of Lamiaceae family (sage, basil and thyme). Optimal conditions with regard to extraction temperature (66-129 °C) and solvent concentration (32-88% methanol) were identified using response surface methodology (RSM). For all three spices, results showed that 129 °C was the optimum temperature with regard to antioxidant activity. Optimal methanol concentrations with respect to the antioxidant activity of sage and basil extracts were 58% and 60% respectively. Thyme showed a different trend with regard to methanol concentration and was optimally extracted at 33%. Antioxidant activity yields of the optimal PLE were significantly (p < 0.05) higher than solid/liquid extracts. Predicted models were highly significant (p < 0.05) for both total phenol (TP) and FRAP values in all the spices with high regression coefficients (R(2)) ranging from 0.651 to 0.999.

Optimization of Application of Delactosed Whey Permeate Treatment To Extend the Shelf Life of Fresh-Cut Tomato Using Response Surface Methodology

Optimization of delactosed whey permeate (DWP) treatment for fresh-cut tomato was accomplished by evaluating different quality, nutritional and microbial markers. Response surface methodology was applied to obtain polynomial model equations. DWP concentration (0-5%) and storage (0-10 days) were used as independent factors in order to optimize the process. The analyses showed that increases in DWP concentration extended the quality of the fresh-cut tomato significantly (p<0.05) by maintaining texture and antioxidant activity (FRAP) and controlling the spoilage during the storage. The total aerobic counts and yeast and molds were reduced by ∼1.5 log cfu/g and ∼1.0 log cfu/g respectively after 10 days of storage treated with 3% DWP. Ascorbic acid and lycopene were retained best within the range of 3 to 5% of DWP treatment. However, concentrations>3% were scored unacceptable by the sensory panel due to perceived off-odors. Predicted models were highly significant (p<0.05) for all the markers studied in fresh-cut tomato with high regression coefficients (R2) ranging from 0.79 to 0.99. The study recommends the use of DWP at a concentration of 3% to extend the shelf life of fresh-cut tomato by preserving its quality and antioxidant properties during storage.

Simultaneous Modelling of the Thermal Degradation Kinetics of Pectin Methylesterase in Lettuce (Lactuca sativa L.) and Carrot (Daucus carota L.) Extracts: Analysis of Seasonal Variation and Tissue Type

The thermal degradation kinetics of pectin methylesterase (PME) from carrot and lettuce were studied. Fresh extracts were exposed to temperatures from 55 to 70 °C until the enzyme was inactivated. A model based on the presence of two forms of the enzyme, one active and one non-active, is proposed. The natural variability of the PME activity was taken into the model in the form of normally distributed random effects. The common model parameters obtained (cleavage constant (0.0395±0.0062 s−1), degradation constant (0.556±0.112 s−1), cleavage energy of activation (469±23 kJ mol−1) and degradation energy of activation (488±18 kJ mol−1)) show that the PME degradation kinetics of the two vegetables can be explained with a single set of parameters.

The effect of delactosed whey permeate on phytochemical content of canned tomatoes

The effect of delactosed whey permeate (DWP) treatment on antioxidant and phyto-chemical components of canned Irish plum tomatoes were investigated. Tomatoes were sterilised for 5 min (F(0)) at 120 °C and stored for 6 months. The DWP treatment retained significantly (p<0.05) higher levels of ascorbic acid and lycopene of tomatoes. The antioxidant activity of DWP treated tomatoes was higher (7%) than the control at the end of storage. The firmness in DWP-treated fruits was around 40% higher than that in control. All the parameters decreased significantly (p<0.05) during storage except lycopene and total phenols. Lycopene content showed no significant change and total phenols increased during storage. The changes in ascorbic acid, antioxidant activity and texture were fitted well to Weibull kinetic models with high coefficients of determination (R(2)) and low RMSE (root mean sum of squared error). The results clearly indicate that DWP enhanced the retention of antioxidant compounds in tomatoes during storage.

Characterization of Blue Whiting Skin Gelatines Extracted After Pretreatment with Different Organic Acids

Gelatines were extracted from blue whiting (Micromesistius poutassou) skins after pretreatment with different organic acids (acetic, citric, lactic, malic, and tartaric acids). The effect of the pretreatment on the chemical composition and the rheological properties of extracted gelatines were analyzed. It was observed that acetic acid pretreatment resulted in significantly (p < 0.05) higher extraction yield compared to the rest of the gelatines. All gelatines, regardless of the organic acid used in the pretreatment, had similar chemical composition (p > 0.05). The amino acid analysis showed that acetic acid pretreated skins resulted in gelatines with higher imino acid levels with respect to the other pretreatments. Acetic and tartaric acid derived gelatine gels showed highly interconnected protein networks and better viscoelastic properties, in terms of storage modulus, compared to the other pretreatments.