Special Issue: Bioactive Compounds, Nutritional Quality, and Oxidative Stability of Edible Oils and By-Products of Their Extraction.

Edible oils (refined, virgin, and cold-pressed oils) are one of the most important components of the daily human diet and have a considerable influence on the proper functioning of our body [...].

Evaluation of Selected Medicinal, Timber and Ornamental Legume Species' Seed Oils as Sources of Bioactive Lipophilic Compounds.

Bioactive lipophilic compounds were investigated in 14 leguminous tree species of timber, agroforestry, medicinal or ornamental use but little industrial significance to elucidate their potential in food additive and supplement production. The tree species investigated were: Acacia auriculiformis, Acacia concinna, Albizia lebbeck, Albizia odoratissima, Bauhinia racemosa, Cassia fistula, Dalbergia latifolia, Delonix regia, Entada phaseoloides, Hardwickia binata, Peltophorum pterocarpum, Senegalia catechu, Sesbania sesban and Vachellia nilotica. The hexane-extracted oils of ripe seeds were chromatographically analysed for their fatty acid composition (GC-MS), tocochromanol (RP-HPLC/FLD), squalene and sterol (GC-FID) content. A spectrophotometrical method was used to determine total carotenoid content. The results showed generally low oil yield (1.75-17.53%); the highest was from H. binata. Linoleic acid constituted the largest proportion in all samples (40.78 to 62.28% of total fatty acids), followed by oleic (14.57-34.30%) and palmitic (5.14-23.04%) acid. The total tocochromanol content ranged from 100.3 to 367.6 mg 100 g-1 oil. D. regia was the richest and the only to contain significant amount of tocotrienols while other oils contained almost exclusively tocopherols, dominated by either α-tocopherol or γ-tocopherol. The total carotenoid content was highest in A. auriculiformis (23.77 mg 100 g-1), S. sesban (23.57 mg 100 g-1) and A. odoratissima (20.37 mg 100 g-1), and ranged from 0.7 to 23.7 mg 100 g-1 oil. The total sterol content ranged from 240.84 to 2543 mg 100 g-1; A. concinna seed oil was the richest by a wide margin; however, its oil yield was very low (1.75%). Either ß-sitosterol or Δ5-stigmasterol dominated the sterol fraction. Only C. fistula oil contained a significant amount of squalene (303.1 mg 100 g-1) but was limited by the low oil yield as an industrial source of squalene. In conclusion, A. auriculiformis seeds may hold potential for the production of carotenoid-rich oil, and H. binata seed oil has relatively high yield and tocopherol content, marking it as a potential source of these compounds.

Effect of the Addition of Selected Herbal Extracts on the Quality Characteristics of Flavored Cream and Butter.

Herbs have been used for centuries in order to enrich food as preservatives, flavorings, and medicinal agents. The aim of this work was to study the effect of the addition of selected herbal extracts (dried leaves of Thymus vulgaris L., Origanum vulgare L., Satureja hortensis L., Rosmarinus officinalis L., and Ocimum basilicum L.) on selected parameters of fermented flavored cream (counts of starter culture bacteria and pH value) and the resulting flavored butter (water content, water distribution, butter plasma pH, butter fat acidity, and oxidative stability), preceded by a study of the activity of the herbal extracts against starter lactic acid bacteria determined using the well diffusion method. The extracts did not inhibit the starter lactic acid bacteria at a fixed level. The presence of the herbal extracts contributed to a shorter fermentation course and influenced the counts of starter culture bacteria during fermentation and refrigerated storage (at 5 °C) for 21 days. The extract additives did not affect the water content or the degree of its dispersion, the butter plasma pH, or the butter fat acidity. The positive effect of the rosemary and thyme extract addition was only noted when analyzing the oxidative stability of the milk fat of the butter.

Oxidative Stability and Antioxidant Activity of Selected Cold-Pressed Oils and Oils Mixtures.

The aim of the study was to analyse the chemical composition and oxidation stability of selected cold-pressed oils and oil mixtures. The oils were tested for their initial quality, fatty acid composition, total phenolic compounds, DPPH, and ABTS free radical scavenging activity. The Rancimat method was used to assess oxidative stability. The obtained results were subjected to principal component analysis (PCA) to determine the influence of selected chemical properties on the oxidative stability of the oil. It has been found that different factors of oil quality influence the stability of cold-pressed oils. The highest correlation coefficient was noted between the induction time, peroxide value, and TOTOX indicator (r = 0.89). Fatty acid composition, including the percentage of SFA, MUFA, PUFA, and the ability to scavenge ABTS captions radicals, did not significantly affect the oxidative stability of the oils. Black cumin seed oil was the most resistant to the oxidation processes in the Rancimat apparatus, mainly due to the high content of phenolic compounds (384.66 mg GAE/100 g). On the other hand, linseed oil and its mixtures were the least stable. Their fatty acid composition was dominated by a polyunsaturated α-linolenic fatty acid, significantly reducing the antioxidant resistance.

Enzymatic Synthesis of Lipophilic Esters of Phenolic Compounds, Evaluation of Their Antioxidant Activity and Effect on the Oxidative Stability of Selected Oils.

The aim of the study was to compare the effect of the substituent and its position in the aromatic ring on the antioxidant activity of hexanoic acid esters obtained in reactions catalyzed by immobilized lipase B from Candida antarctica. 4-Hydroxybenzyl hexanoate, 2-hydroxybenzyl hexanoate, 4-methoxybenzyl hexanoate, and vanillyl hexanoate were obtained with conversion yields of 50 to 80%. The antioxidant activity of synthesized esters, their alcohol precursors and BHT (Butylated HydroxyToluene) was compared with DPPH (2,2-diphenyl-1-picrylhydrazyl), CUPRAC (cupric ion reducing antioxidant capacity), and CBA (crocin bleaching assay) methods. Furthermore, it was investigated whether the presence of vanillyl hexanoate in a concentration of 0.01 and 0.1% affected the oxidative stability of sunflower and rapeseed oils in the Rancimat test. It was observed that the antioxidant activity of hexanoic acid esters depends on the presence and position of the hydroxyl group in the aromatic ring. The highest activities were found for vanillyl alcohol, vanillyl hexanoate, and BHT. The addition of the ester and BHT significantly extended the induction times of the tested oils, and these compounds exhibited similar activity. Vanillyl hexanoate increased the induction time from 4.49 to 5.28 h and from 2.73 to 3.12 h in the case of rapeseed and sunflower oils, respectively.

Roasting pumpkin seeds and changes in the composition and oxidative stability of cold-pressed oils.

BACKGROUND: Pumpkin seed oil is valuable oil for its distinctive taste and aroma, as well as supposed health- promoting properties. The aim of this study was to investigate how roasting pumpkin seeds influences the physicochemical properties of cold-pressed oils. METHODS: The fatty acid composition, content of phytosterols, carotenoids and tocopherols, oxidative stability and colour were determined in oils after cold pressing and storage for 3 months using GC-FID, GCxGC-ToFMS, HPLC, Rancimat and spectrophotometric methods. RESULTS: The results of this study indicate that the seed-roasting and storage process have no effect on the fatty acid composition of pumpkin seed oils, but does affect phytosterols and tocopherols. The carotenoid content decreased after storage. The colour of the roasted oil was darker and changed significantly during storage. CONCLUSIONS: Pumpkin oil obtained from roasted seeds shows better physicochemical properties and oxidative stability than oil from unroasted seeds.

Comparison of the oxidative stability of linseed (Linum usitatissimum L.) oil by pressure differential scanning calorimetry and Rancimat measurements.

The aim of this study was to compare the oxidative stability of linseed oil using the pressure differential scanning calorimetry (PDSC) and Rancimat methods, and to determine the kinetic parameters of linseed oil oxidation. Five cold pressed linseed oils were oxidized at different temperatures under PDSC (90-140 °C) and Rancimat (70-140 °C) test conditions. The oxidative stability of the linseed oils was calculated based on induction times (PDSCτmax, Rancimat τon), the Arrhenius equation and activated complex theory, frequency factors (Z), the reaction rate coefficient (k) for all temperatures, activation energies (Ea), Q10 numbers, activation enthalpies (∆H++), and activation entropies (∆S++). The PDSC method was more convenient for the determination of the induction time of linseed oils than the Rancimat method. During oxidation measurement by Rancimat method, the linseed oil polymerized, which affected the measurements. The reaction rate coefficient increased with rising temperature during measurement by both methods. The activation energy values of linseed oil oxidation using the PDSC and Rancimat methods ranged from 93.14 to 94.53 and 74.03 to 77.76 kJ mol-1, respectively. The Q10 , ∆H++, and ∆S++ values for the analyzed linseed oils were between 2.11-2.13, 90.54-91.30 kJ mol-1, -33.20 to -30.90 J mol K-1 calculated by PDSC measurements, and 2.23-2.32, 71.03-74.76, -59.42 to -49.08 J mol K-1 by Rancimat measurements, respectively.

Blends of rapeseed oil with black cumin and rice bran oils for increasing the oxidative stability.

For the increase of oxidative stability and phytonutrient contents of rapeseed oil 5, 10 and 20 % blends with rice bran oil and black cumin oil were prepared. Profiles of different bioactive lipid components of blends including tocopherols, tocotrienols, phytosterols and phytostanols as well as fatty acid composition were carried out using HPLC and GLC. Rancimat was used for detecting oxidative stability of the fatty material. The blends with black cumin seed oil characterized higher level of α- and γ-tocopherols as well as all isomers of tocotrienols. Presence of rice bran oil in blends leads to increased tocotrienols amounts, ß-sitosterol and squalene. Blending resulted in lowering ratio of PUFA/SFA and improves stability of these oils. The ratio of omega-6/omega-3 raises from 2.1 in rapeseed oil to 3.7 and 3.0 in blends with black cumin and rice bran oils, respectively. Addition of 10 and 20 % of black cumin and rice bran oils to rapeseed oil were influenced on the oxidative stability of prepared blends. The results appear that blending of rapeseed oil with black cumin seed oil or rice bran oil enhanced nutritional and functional properties via higher oxidative stability as well as improved phytonutrient contents.

Influence of impurities in raw material on sensory and physicochemical properties of cold-pressed rapeseedoil produced from conventionally and ecologically grown seeds.

BACKGROUND: The main problem of cold-pressed technology is its low yield and the varying quality of the end product, which is dependent on the quality of the raw material, technological process applied and also on conditions of packaging and storage. The effects of different contents of impurities in rapeseed on the sensory, physicochemical properties and oxidative stability of rapeseed oil produced by cold-pressing were investigated. METHODS: Cold-pressed oil produced from conventionally grown rapeseeds (individual cultivars and industrial seeds) and certified ecological rapeseeds. Quantified quality parameters included the following: the content of impurities, acid value, peroxide value, spectrophotometric indices (K232, K268), oxidative stability determined by the Rancimat test, pheophytin a content, and sensory assessment. RESULTS: The seeds which were homogenous in terms of cultivar contained the lowest level of impurities (up to 1.3%) and differed significantly in this regard from ecological and industrial seeds. It was found that the presence of impurities exerts an adverse effect on the sensory and physicochemical characteristics of the oil. Impurity content exceeding 5% resulted in the appearance of off -flavours, such as woody, strawy and fusty/musty. Furthermore, a positive correlation was found between impurity content and acid value (r = 0.781), peroxide value (r = 0.656), anisidine value (r = 0.645), K232 (r = 0.625), while in the case of oxidative stability, no such correlation was observed. CONCLUSIONS: The type and percentage of seed impurities in the rape crop determines the sensory and physicochemical properties of the cold-pressed oil. It seems advisable, therefore, to minimize the amount of impurities, in order to obtain high-quality cold-pressed rapeseed oil.