J.P.H. Linssen

Antioxidant activity of extracts obtained by different isolation procedures from some aromatic herbs grown in Lithuania.

An increasing demand for natural additives has shifted the attention from synthetic to natural antioxidants. The present work examines the potential of some aromatic herbs grown in Lithuania as a source of natural antioxidants: marjoram (Majorana hortensis Moench), catnip (Nepeta cataria L), oregano (Origanum vulgare L), lavender (Lavandula angustifolia Mill), thyme (Thymus vulgaris L), hyssop (Hyssopus officinalis L), anise hyssop (Lophantus anisatus Benth), and sage (Salvia officinalis L). Dried herb samples were submitted to extraction with supercritical CO2, acetone or methanol/water and hydrodistillation. Deodorised herb samples (after removal of essential oil) were also extracted with acetone. The antioxidant activity of these extracts, essential oils and dried deodorised aqueous extracts was assessed by the β-carotene bleaching test (diffusion and spectrophotometric methods). The highest yields of extracts were obtained using polar solvents. Thyme and sage acetone oleoresins showed high antioxidant activity in the tests performed and were regarded as the most promising sources.

Lipid oxidation in n − 3 fatty acid enriched Dutch style fermented sausages

Dutch style fermented sausages were manufactured with a substitution of 10%, 15% and 20% of pork backfat by flaxseed oil and canola oil, pre-emulsified with soy protein isolate. The 15% and 20% substitution were also reached by adding encapsulated flaxseed oil and encapsulated fish oil and by adding flaxseed oil, pre-emulsified with sodium caseinate, respectively. The products were sliced, packaged in an oxygen-enriched atmosphere and stored in the dark for 12 weeks at 7°C. No differences were detected in moisture, protein and fat content between control and modified sausages, with the exception of the formulation with sodium caseinate. The PUFA/SFA ratio increased from 0.30 in the control to 0.42-0.48 in the sausages with canola oil and to 0.49-0.71 in the sausages with flaxseed oil. The n-6/n-3 ratio decreased from 11.20 in the control to 6.94-5.12 in the sausages with canola oil and to 1.93-1.05 in the sausages with flaxseed oil. The addition of canola oil and encapsulated flaxseed oil resulted in a comparable shelf life as the control in terms of lipid oxidation. In the samples with addition of pre-emulsified flaxseed oil, especially with sodium caseinate, lipid oxidation clearly increased during storage. Physical and sensory analysis showed that the sausages with encapsulated fish oil and flaxseed oil resembled the control most.

Phenolic Compounds in Virgin Olive Oils: Fractionation by Solid Phase Extraction and Antioxidant Activity Assessment

The polar fraction of virgin olive oil was separated into two main parts (A and B) using solid phase extraction. Analysis of individual components by RP-HPLC indicated that the part (A) contained only simple phenols and phenolic acids. Part (B) had a complex nature. The two parts tested for their antioxidant activity showed relatively high protection factors in safflower oil stored at 80°C. Part B was found to contribute more than part A to the stability of the oil. The antioxidant activity of both fractions was related to their content of total polyphenols and o-diphenols. Acidic and alkaline hydrolysis showed significant quantitative changes in the HPLC profiles indicating the presence of ether and ester bonds while high-performance anion exchange chromatography of sugars after hydrolysis gave evidence for the presence of only traces of glycosides. A first attempt to identify a characteristic chromatographic peak of part B by HPLC fractionation and mass spectrometry showed the presence of an ester of tyrosol most probably with a dicarboxylic acid.

Methods of analysis for cell-wall Polysacharides of Fruit and vegetables

ZusammenfassungSaure and neutrale Zuckerbausteine der Pplysaccharide wurden im Ethanol unlöslichen Rückstand verschiedener Frucht- and Gemüsearten bestimmt, sowie in der Pectin-, Hemicellulose- and Cellulose-Fraktion dieser Rückstände. Für die Uronsäure-Bestimmung mittels molekularer Absorptionsspektrometrie wurden die Resultate aus enzymatischer, saurer und alkalischer Extraktion verglichen. Die Gehalte an Neutralzuckern wurden gaschromatographisch bestimmt sowohl nach Hydrolyse mit Enzymen and Trifluoressigsäure (Konzentration 2 mol/1) als auch nach Saeman-Hydrolyse (Schwefelsäure, H+-Konzentration 0,8 mol/1 oder 2 mol/1). Uronsäuregehalte, mit der m-Hydroxydiphenyl-Reaktion und mittels Kupferionenbindung bestimmt, liegen in der gleichen Größen-ordnung. Die Zuckerzusammensetzung der Muster und Fraktionen weisen große Unterschiede auf.SummaryUronides and saccharides were determined in the ethanol-insoluble residue of some fruits and vegetables, and in the pectin, hemicellulose and cellulose fractions of that residue. For molecular absorption spectrometry of uronides, enzymic, acidic and alkaline extraction were compared. The sugar composition was determined by gas chromatography after enzymic hydrolysis and trifluoroacetic acid (concn. 2 mol/1) or Saeman hydrolysis [sulphuric acid (concn. of H+ 0.8 mol/1 or 2 mol/1)]. Uronide contents found by molecular absorption with m-hydroxydiphenyl and copper binding were of the same order of magnitude. Saccharide composition of samples and fractions varied widely.

Combined gas chromatography and sniffing port analysis of volatile compounds of mineral water packed in polyethylene laminated packages

Abstract Commercial mineral waters packed in polyethylene-lined aluminium/cardboard packages were incubated at 40°C and sensorially evaluated for intensities of the descriptors: synthetic, musty, sickly, metallic, astringent and dry. Tasting of these samples with the use of nose clips diminishes the intensities of the descriptors significantly, except for dry. Volatile compounds of this mineral water were analysed by sniffing the effluent of a gas chromatographic column, which provided similar descriptors as above. The components detected by sniffing were tentatively identified by combined gas chromatography and mass spectrometry as being mainly aromatic hydrocarbons and carbonyls. Semiquantitative analysis showed that the concentrations of the compounds which migrated into the mineral water ranged between 10 and 15 ppb. Storage at elevated temperatures seems to involve flavour deterioration, because no taint was observed in mineral water samples, which were incubated at 20°C.

Quality characteristics of Dutch-style fermented sausages manufactured with partial replacement of pork back-fat with pure, pre-emulsified or encapsulated fish oil

Dutch-style fermented sausages were manufactured with 15% and 30% pork back-fat substitution by pure or commercial encapsulated fish oil, either added as such or as pre-emulsified mixture with soy protein isolate. Adding commercial encapsulated fish oil was the most important factor influencing the chemical composition. The fat content was not significantly different between products (p>0.05). The n-6/n-3 ratio decreased from 8.49 in controls to 0.90-2.47 in modified products. Lipid oxidation parameters (propanal and hexanal) showed much higher values for sausages with pure fish oil than for products with encapsulated oil. For the latter, lipid oxidation was similar to controls. Products with encapsulated or pre-emulsified oil were significantly firmer than products from other treatments in physical and sensory analysis (p<0.05). Overall, it is technologically feasible to enrich dry fermented sausages with n-3 fatty acids from fish oil and the application of commercial encapsulated fish oil seems to be the best in retaining overall quality.

Influence of flavour absorption on oxygen permeation through LDPE, PP, PC and PET plastics food packaging

The effect of flavour absorption on the oxygen permeability of low-density polyethylene (LDPE), polypropylene (PP), polycarbonate (PC) and polyethylene terephthalate (PET) was studied using an isostatic continuous flow system. Polymer samples were exposed to a model solution containing limonene, hexyl acetate, nonanone and decanal at 40°C. After exposure, one part of each sample was analysed for absorbed flavour compounds using a Large Volume Injection GC Ultrasonic ‘in vial’ extraction method, and from the other part, oxygen permeability was measured in a permeation cell at 25°C. After 8h of exposure, LDPE and PP samples showed a significant linear (R2 = 0.82 and 0.99) increase in oxygen permeability of 21 and 130%, respectively. Owing to swelling of the polymer samples resulting from flavour absorption, the structure of the polymeric network changed (i.e. opened) and consequently increased oxygen permeability. The oxygen permeability of exposed PC showed a significant linear (R2 = 0.78) decrease of 11% after 21 days. PC obviously did not swell like LDPE or PP. Therefore, it was suggested that absorbed flavour compounds occupied or blocked ‘microcavities’ through which normally oxygen is transported. Absorption of flavour compounds by PET did not affect the oxygen permeability of PET significantly.

Influence of food matrix on absorption of flavour compounds by linear low-density polyethylene: proteins and carbohydrates

The influence of oil and food components in real food products on the absorption of four flavour compounds (limonene, decanal, linalool and ethyl 2-methyl butyrate) into linear low-density polyethylene (LLDPE) was studied using a large volume injection GC in vial extraction method. Model food systems and real food products investigated included oil/water emulsions, oil/casein models, oil/pectin models, skim milk and whole milk. A small amount of oil (50 g l-1) had a major influence on the amount of flavour absorption. Because of solubilization of the more apolar flavour compounds limonene, decanal and linalool into the oily phase, only the remaining flavour compounds in the aqueous phase were available for absorption by LLDPE. After 14 days of exposure, absorption of limonene and decanal decreased by 97°and that of linalool by 86ÐDue to a salting out effect, absorption of the less apolar ethyl 2-methylbutyrate (E2MB) first increased with increasing oil concentration, but decreased at higher oil concentrations (>2.5 g l-1). Oil/casein and oil/pectin models showed that the more apolar flavour compounds were mainly dissolved in the oily phase and that the compounds present in the aqueous phase could interact with casein or pectin. Oil influenced the level of flavour absorption by LLDPE to a much greater extent than pectin or casein. However, the low amount of fat (1.11 g l-1) in skim milk had no influence on the absorption of flavour compounds. Only the proteins in skim milk (especially casein) decreased the absorption of limonene and decanal, because the fat was probably entrapped. Whole milk, which contained a higher concentration of (free) fat, suppressed the absorption of all flavour compounds by LLDPE to the same extent as was found for the oil model solutions. In general, absorption results from skim milk and whole milk were in good agreement with the results of the investigated model solutions containing individual food components.

Influence of flavour absorption by food-packaging materials (low-density polyethylene, polycarbonate and polyethylene terephthalate) on taste perception of a model solution and orange juice

The influence of flavour absorption by low-density polyethylene (LDPE), polycarbonate (PC) and polyethylene terephthalate (PET) on taste perception of a model solution containing seven flavour compounds and orange juice in glass bottles was studied with and without pieces of the respective plastic films after dark storage at 20°C. Owing to absorption, the amount of flavour compounds in the model solution exposed to LDPE decreased substantially. From the model flavour solution valencene was almost completely absorbed by LDPE, followed to a lesser extent by decanal, hexyl acetate, octanal and nonanone. Less flavour compounds were absorbed from the model solution by PC and PET. In contrast to LDPE, valencene was absorbed in the lowest amounts and decanal in the highest. Limonene was readily absorbed from orange juice by LDPE, while myrcene, valencene, pinene and decanal were absorbed in smaller quantities. Only three flavour compounds were absorbed from orange juice by PC and PET in very small amounts: limonene, myrcene and decanal. Although the flavour content between controls and polymer-treated samples differed substantially, the loss of flavour compounds due to absorption by LDPE, PC and PET did not influence taste perception of a model solution and orange juice significantly up to 29 days of dark storage at 20°C as determined by triangular taste panel tests.

Antioxidant activity of horehound (Marrubium vulgare L.) grown in Lithuania

Acetone extracts (AE), deodorised acetone extracts (DAE), and deodorised water extracts (DWE) from leaves of horehound (Marrubium vulgare L. ) were tested for their antioxidant activity in rapeseed ( Brassica napus L.) oil at 80 °C. Well investigated antioxidants containing extracts (AE and DAE) of sage (Salvia officinalis L.) were used for comparison purposes. The effect of the extracts on the edible oil stability was assessed by measuring weight gain, peroxide value, and the UV absorption. The antioxidant activity of AE and DAE of horehound were comparable to the antioxidant activity of AE and DAE of sage. For both plants AE was shown to have better antioxidant properties than DAE. The volatile components of horehound were hydrodistilled and analysed by GC and GC/MS. Totally, 47 components were identified in the essential oil (EO), the main ones being (Z)- β-farnesene, βcaryophyllene, (E)-hex-2-enal, α-humulene, and germacrene D. Thirtynine constituents are reported in M. vulgare for the first time.