The Effect of Monoglyceride Addition on the Rheological Properties of Pistachio Spread

Pistachio nut (Pistacia vera L.) is one of the most delicious and nutritious nuts in the world. In this study, monoglycerides (0.0–1.5 %) as lipophilic emulsifiers were used to prevent oil separation in pistachio spread A (containing 50.0 % pistachio paste, 30.0 % icing sugar and 20.0 % red palm oil) and B (containing 58.3 % pistachio paste, 25.0 % icing sugar and 16.7 % red palm oil). Changes in rheological behavior of pistachio spreads were investigated. The highest work of shear (which indicates spreadability) was observed in Formulations A and B containing 1.5 % monoglycerides. Addition of emulsifier significantly (P < 0.05) influenced the consistency index (K), thixotropic area (A), yield stress (τ ₀) and coefficient correlation (R) of pistachio spreads. All the pistachio spreads that contained emulsifier exhibited a higher storage modulus (G′) than the loss modulus (G″).     

Influence of Sodium Alginate and Genipin on Stability of Chitosome Containing Perilla Oil in Model and Real Drink

The impacts of sodium alginate (SA) and genipin (GP) on low‐pH and thermal stability of chitosan‐coated liposome (chitosome), as a carrier of perilla oil, are investigated in a model drink. Oxidative stability, as well as quality parameters and sensory evaluation, are analyzed during 60 days of storage at 25 °C as well as in orange drink fortified with non‐coated and coated nanoliposome. The investigation of model drink shows that low‐pH and heating stability of nanoliposome are influenced by the type of coating biopolymer and can be improved by chitosan (CS) and GP. The coating by different biopolymers has fewer changes in quality parameters (°Brix and pH value, total acidity, and color difference), and shows higher oxidative stability than emulsified perilla seed oil and bare nanoliposome after storage at 25 °C for 60 days. The results indicate that the type of biopolymer and cross‐linkers plays a key role in the liposomal membrane structure stability. Practical applications: The present study is anticipated to promote a better understanding of the advantages of combining nanoliposomes (NLs) with the primary and secondary coatings as well as cross‐linkers to overcome the low oxidative stability of perilla oil (as a source of plant rich in n‐3 polyunsaturated fatty acids [PUFAs]) and semi‐permeability of NL membrane in like and real foods. It could also reduce the adverse effects of n‐3 PUFAs on sensory properties of orange drink and pave the way for making liposomes applicable to foods and drinks.     

Preparation and Characterization of Virgin Olive Oil‐Beeswax Oleogel Emulsion Products

Virgin olive oil and beeswax were used to prepare four oleogel emulsions (EM1–EM4) through simultaneous oleogelation emulsification, and these oleogels were compared with breakfast margarine (BM). The melting temperatures of the oleogel emulsions ranged from 52.29 to 57.52 °C, while it was 40.36 °C for the BM sample. Similarly, the solid fat content (SFC) of the oleogel emulsions was between 3.57 and 3.68 % at 20 °C, and that of BM was 7.70 %. Except the EM3 sample, all oleogel emulsions exhibited mechanical stability. The firmness and stickiness values of the oleogel emulsion samples were lower than those of the BM sample, but they remained almost constant through 90 days of storage. Furthermore, the fine water droplets and needle‐like beeswax crystals within the continuous oil phase were stable during the storage. The X‐ray diffraction patterns of the samples revealed that the oleogel emulsions contain crystals similar to β′ polymorphs, characterized by a homogenous, smooth and fine texture. The presence of inter and intramolecular hydrogen bonds was proved by Fourier Transform Infrared (FT‐IR) measurements. The developed oleogel emulsions were found to be stable in terms of texture, color and oxidation during 90 days of storage. In conclusion, these oleogel emulsion products can be used as margarine/spread stocks.     

Effect of roasting on oxidative and tocopherol stability of walnut oil during storage in the dark

The effect of roasting on the oxidative stability of oil from walnut (Juglans sinensis Dode) was investigated by observing changes in the characteristics of oils from unroasted and roasted kernels during storage in the dark at 60°C. Walnut kernels were roasted at 160°C for 15 min prior to oil extraction with the solvent, hexane. Roasting of kernels increased the peroxide value (POV) and conjugated dienoic acid (CDA) value of the oil. The rate of increase in the POV was significantly lower in roasted than in the unroasted walnut oil during storage at 60°C (1.90 vs. 1.06 and 4.45 vs. 3.55 meq/kg/day during induction period (IP) and post‐IP, respectively). Roasting of kernels significantly increased the IP of walnut oil from 0.89 to 3.39 days during storage. The total tocopherol content in roasted walnut oil was lower as compared to that in unroasted one (277.77 vs. 314.88 µg/g). However, the rate of degradation of total tocopherol during storage was lower in roasted walnut oil compared to unroasted one (1.18 vs. 2.17%/day), which showed that the tocopherol retention was higher in roasted walnut oil. These results indicate that roasting of kernels increased the oxidative and tocopherol stability of oil during storage in the dark.     

Pigments for Aquaculture of Salmonids. A Comparative Model Study of Carophyll Pink and Panaferd AX in Cod Liver Oil

As one of the key ingredients in feed for rearing salmon the stability of the synthetic feed pigment Carophyll Pink^® (CP) and the natural pigment Panaferd‐AX^® (PAN) in pure cod liver oil were investigated. As reference, pure cod liver oil without added carotenoids was used (PURE). Carotenoid content, isomerization of astaxanthin in CP and distribution of carotenoids in PAN and the antioxidant ability of CP and PAN were followed by HPLC in two model experiments (Experiment 1: 17 days, temperature 18.5–28.2 °C, and Experiment 2: 15 days, temperature 29.7 °C). Moreover, peroxide value (PV), thiobarbituric value (TBARS) and fatty acid (FA) compositions were analyzed in CP, PAN and PURE. Relative to cod liver oil with added PAN, addition of CP resulted in significantly higher stability of ∑PUFA, slower formation of peroxides, reduced oxidation and increased carotenoid stability during storage. For the isomerization of astaxanthin in CP a significantly decrease in all‐E‐astaxanthin and an increase in 13Z‐astaxanthin was observed during storage in both experiments. Highest stability of different carotenoids in PAN were found for the carotenoid β‐carotene in both experiments, followed by echinenone and astaxanthin in Experiment 1 and astaxanthin, adonirubin and adonixanthin in Experiment 2. It is concluded that the synthetic pigment feed additive CP significantly improves the stability of cod liver oil as compared to the natural pigment feed additive PAN (order of stability; CP > PAN > PURE).     

Preparation and characterization of highly stable monodisperse argan oil‐in‐water emulsions using microchannel emulsification

Argan oil is well known for its nutraceutical properties. Its specific fatty acid composition and antioxidant content contribute to the stability of the oil and to its dietetic and culinary values. There is an increasing interest to use argan oil in cosmetics, pharmaceutics, and food products. However, the formulation of highly stable emulsions with prolonged shelf life is needed. In this study, argan oil‐in‐water (O/W) emulsions were prepared using microchannel (MC) emulsification process, stabilized by different non‐ionic emulsifiers. The effects of processing temperature on droplet size and size distribution were studied. Physical stability of argan O/W emulsions was also investigated by accelerated stability testing and during storage at room temperature (25 ± 2°C). Highly monodisperse argan O/W emulsions were produced at temperatures up to 70°C. The obtained emulsions were physically stable for several months at room temperature. Furthermore, emulsifier type, concentration, and temperature were the major determinants influencing the droplet size and size distribution. The results indicated that a suitable emulsifier should be selected by experimentation, since the interfacial tension and hydrophilic–lipophilic balance values were not suitable to predict the emulsifying efficiency. Practical applications: MC emulsification produces efficiently monodisperse droplets at wide range of temperatures. The findings of this work may be of great interest for both scientific and industrial purposes since highly stable and monodisperse argan oil‐in‐water emulsions were produced which can be incorporated into food, cosmetic, or pharmaceutical formulations.     

Oxidative Stability of Microencapsulated Kenaf Seed Oil Using Co-extrusion Technology

This study investigates the effect of microencapsulation (via co‐extrusion technology using high methoxyl pectin‐enhanced alginate as a shell formulation) on the storage stability and antioxidant properties of kenaf seed oil. Microencapsulated kenaf seed oil (MKSO) and unencapsulated oil were stored at 25 °C for 28 days and at 65 °C for 24 days. The oils were then subjected to stability and quality evaluation based on peroxide, p‐anisidine, and total oxidation values, conjugated diene and triene levels, thiobarbituric acid reactive substances, free fatty acids, total phenolic content, and the radical scavenging activity assays of 2,2‐diphenyl‐1‐picrylhydrazyl and 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulphonic acid). The results showed that there was a significant increase (p < 0.05) in oxidation and a significant decrease (p < 0.05) of antioxidant activity in the unencapsulated oil while oxidation changes generally occurred more slowly in MKSO. It was demonstrated that the current microencapsulation method is a feasible approach to enhance oxidative stability of kenaf seed oil.     

Physical‐chemical characteristics and oxidative stability of oil obtained from lyophilized raspberry seed

Fresh raspberry (Rubus idaeus), cultivar Willamette, was freeze‐dried (lyophilization). A byproduct of lyophilization is “fine dust” of raspberry consisting of finely ground raspberry fruit body and seed. The seeds were separated. The seed oil was isolated and its physical and chemical characteristics were determined. Parameters that characterize the seed and quality of the oil were examined, including fatty acid composition, oxidative stability under different storage conditions, and radical‐scavenging activity. The fatty acid composition was determined by GC/FID and the contents of the dominant fatty acids were found as: oleic 16.92%, linoleic 54.95%, and α‐linolenic acid 23.97%. The oxidative stability of the oil was poor. The induction period by Rancimat test at 100 °C was 5.2 h. The radical‐scavenging activity is similar to that of resveratrol [1,3‐benzenediol 5‐(1^E‐2‐4‐hydroxy‐phenyl‐ethyl)]. Although this product is used in the candy industry, it would be far more useful if raspberry oil of satisfactory quality could be extracted. This paper demonstrates that sifted lyophilized seeds can be used for the extraction of oils. This process allows for maximal usage of the byproducts, reduces losses and it increases the development of new products.     

Bleaching augments lipid peroxidation products in pistachio oil and its cytotoxicity

Pistachio consumption is associated with reductions in serum cholesterol and oxidative stress due to their constituents of unsaturated fats, phytosterols, fiber, and antioxidants. Bleaching has been applied to whiten nut shells for antifungal and cosmetic purposes. However, the impact of bleaching on nutritional quality and safety of pistachios remains to be examined. In this study, we investigated whether bleaching would increase malondialdehyde (MDA) or 7‐keto‐sitosterol and decrease phytosterols in pistachio oil, as well as cause cytotoxicity of modeled Hepa1c1c7 cells. Bleaching increased MDA by more than 32% from 0.23 µg/g in raw oil, with the largest increase noted with the bleach containing H₂O₂ and Fe²⁺ (P ≤ 0.05). Bleached pistachio oil had larger than 12.6% decrease in β‐sitosterol and total phytosterols as compared to the raw oil (P ≤ 0.05). Bleaching with Fe²⁺ significantly increase 7‐keto‐sitosterol compared to bleaching alone. Hepatic cell viability was decreased the most by the oil of the pistachios treated with bleach containing Fe²⁺ (P ≤ 0.05), and lactate dehydrogenase activity in medium was elevated by >18‐folds (P ≤ 0.05). Compared to natural pistachios, the bleaching treatment had detrimental effects on nutritional quality and expected health benefits of pistachios by increasing lipid peroxidation, decreasing phytosterol content, and causing cytotoxicity. Practical applications: Bleaching has been applied to whiten the nut shell for antifungal and cosmetic purposes. However, the results of this study indicate that bleaching treatment has a detrimental impact on nutritional quality and expected health benefits of pistachios. Particularly, treatment with a bleach formula with hydrogen peroxide and transit metals increases formation of lipid peroxidation products and decreases phytosterol content. The resulting pistachio oil causes cell toxicity. Thus, bleaching practice for whitening pistachios is strongly discouraged.     

Stability Assessment of Virgin Coconut Oil‐Based Emulsion Products

In recent years, there has been dramatic growth in the market for virgin coconut oil (VCO). VCO, a promising functional food oil, has gained popularity and captured public attention worldwide. Two VCO‐based emulsion products were developed as a new nutritional food supplement with the aim of increasing the consumption of VCO. The stability of VCO‐based emulsion products was assessed during a storage period of 3 months to gauge the quality of the optimized VCO‐based emulsions. The particle‐size distributions of the VCO‐based emulsions remained stable throughout the 3‐month storage period at 25 and at 50°C. However, a slight increase in the particle sizes was observed in the VCO‐based emulsions samples after 2 months of storage at 4 °C. Nevertheless, phase separation did not occur in either of the VCO‐based emulsions products throughout the storage‐stability assessment period. No signs of microbial growth were detected in the emulsion products during the storage period. Furthermore, no significant changes in the free fatty acid contents of the emulsion products were observed during storage at 4 or 25°C throughout the storage period. The VCO‐based emulsion products possessed sufficient emulsion stability to withstand changes at different storage temperatures.     

Effect of Positional Distribution of Linoleic Acid on Oxidative Stability of Triacylglycerol Molecules Determined by 1H NMR

¹H nuclear magnetic resonance (¹H NMR) was used to determine the effect of positional distribution of linoleic acid (L) on the oxidative stability of triacylglycerols. For this purpose, structured soybean oil (SSO), which had a similar total fatty acid composition but a different L positional distribution than soybean oil (SO), was produced by interesterification reaction. The SO and SSO were oxidized in the dark at 40 °C. Afterwards, ¹H NMR was used to monitor the oxidation process and quantify the main polyunsaturated fatty acid, Z,E‐ and E,E‐conjugated forms, hydroperoxides, and aldehydes at different oxidation periods in a single run. After 45 days of oxidation, SSO showed lower L content than SO (9.9 ± 1.1 and 16.8 ± 0.5 %, respectively). Additionally, secondary oxidation products in SSO were shown to be more abundant than in SO (82.3 ± 4.9 and 43.6 ± 0.9 mmol/L oil, respectively). This study indicated that SO, which contains a higher distribution of L at the sn‐2 position, was more resistant to autoxidation than SSO.     

Oxidative stability of black cumin (Nigella sativa L.), coriander (Coriandrum sativum L.) and niger (Guizotia abyssinica Cass.) crude seed oils upon stripping

Information on stability of edible oils is important for predicting the quality deterioration of the oil during storage and marketing. Stripping of crude oils removes most of non‐triacylglycerol components, including polar lipids and phenolics. Oxidative stability of black cumin (Nigella sativa L.), coriander (Coriandrum sativum L.) and niger (Guizotia abyssinica Cass.) crude and stripped seed oils was investigated and compared. The factors influencing the oxidative stability of different seed oils were also discussed. Oil samples were stored under accelerated oxidation conditions for 21 d. The progress of oxidation at 60 °C was followed by recording the ultraviolet absorptivity and measuring the formation of oxidative products (peroxide and p‐anisidine values). Inverse relationships were noted between peroxide values and oxidative stabilities and also between secondary oxidation products, measured by p‐anisidine value and stabilities at termination of the storage. Absorptivity at 232 nm and 270 nm increased gradually with the increase in time, due to the formation of conjugated dienes and polyenes. In general, oxidative stabilities of crude oils were stronger than their stripped counterparts and the order of oxidative stability was as follows: coriander > black cumin > niger seed. Levels of polar lipids in crude oils correlated with oxidative stability. Thus, the major factor that may contribute to the better oxidative stability of crude oils was the carry‐over of their polar lipids.     

Physicochemical and thermal characterization of seed oil from Mexican mamey sapote <Emphasis Type="Italic">(Pouteria sapota)</Emphasis>

The aim of this research was to perform a physicochemical characterization of native mamey sapote seed oil [Pouteria sapota (Jacq.) H.E. Moore and Stearn]. Mamey sapote seed oil showed good oxidative stability as it had low peroxide, free fatty acid, and p‐anisidine values. The main fatty acids present in the oil were palmitic, stearic and oleic acid, constituting five major triacylglycerides families: PLP, POP, StOO, POSt and StOSt. Crystallization and melting points of the oil were ?37.7 and 23.84 °C, respectively. The oil had higher SFC when the temperature was lower than 10 °C. X‐ray diffraction patterns showed that prolonged storage times lead to the formation of β crystals. Micrographs showed granular crystals (91–105 μm), with needle edges similar to cocoa butter. In addition, mamey sapote seed oil can be used in confectionery products or as a possible substitute for cocoa butter to improve and obtain good‐quality products.     

Interlaboratory study on lipid oxidation during accelerated storage trials with rapeseed and sunflower oil analyzed by conjugated dienes as primary oxidation products

Accelerated storage tests are frequently used to assess the oxidative stability of foods and related systems due to its reproducibility. Various methods and experimental conditions are used to measure lipid oxidation. Differences between laboratories make it necessary to determine the repeatability and reproducibility of oxidation tests performed under the same conditions. The objective of the present interlaboratory study was to evaluate the outcome of a storage test for two different bulk oils, sunflower oil (SFO) and rapeseed oil (RSO), during a period of 9 weeks at 20°C, 30°C, 40°C, and 60°C. Sixteen laboratories were provided with bottled oils and conducted the storage tests according to a detailed protocol. Lipid oxidation was monitored by the formation of conjugated dienes (CD) and the activation energy (E_a) was determined for comparative purposes and statistically evaluated. An increase in CD formation was observed for both oils when the storage temperature was increased in all laboratories. The E_a,1 ranged from 47.9 to 73.3 kJ mol⁻¹ in RSO and from 27.8 to 62.6 kJ mol⁻¹ in SFO, with average values of 58.2 and 46.8 kJ mol⁻¹, respectively. The reproducibility coefficients were 10.9% and 18.2% for RSO and SFO, respectively. Practical applications: In order to compare results on oxidative stability of foods derived from different studies, the reproducibility of storage tests and methods employed to evaluate the oxidation level should be considered. This study provides fundamental data on the reproducibility of lipid oxidation under accelerated storage conditions and defines important parameters to be considered for the conduction of experiments.     

Oxidation kinetics in olive oil triacylglycerols under accelerated shelf‐life testing (25–75 °C)

A kinetic study of the autoxidation reaction in olive oil triacylglycerols stored in darkness at different temperatures (25, 40, 50, 60 and 75 °C), in absence of pro‐ and antioxidant compounds to avoid confounding effects, is described. After the induction period (IP) the decrease in the oxidizing substrate and the formation of primary oxidation products followed a pseudo‐zero‐order kinetic, and the calculated E_a from the Arrhenius equation for the formation of hydroperoxides was 32.1 kJ·mol^?1. The formation of secondary oxidation products followed a pseudo‐first‐order kinetic whose rate reaction constant also increased exponentially with temperature. The first oxidation index to exceed the upper limit in the EU regulations was PV, followed by K₂₃₂ and K₂₇₀. The time required reaching these limits and the rancidity threshold showed a potential dependence on temperature, and therefore with accelerated storage at 75 °C, POO shelf‐life in ambient conditions (25 °C) can be predicted. Finally, there was a good linear relationship between the time required to reach the rancidity threshold and the IP of the formation of the 2,4‐decadienal, and hence this instrumental determination could be useful to measure sensory recognition of the rancid defect in POO.     

Canola Proteins Used as Co‐Emulsifiers with Phospholipids Influence Oil Oxidability,Enzymatic Lipolysis,and Fatty Acid Absorption in Rats

The objective of this study is to formulate and characterize oil‐in‐water emulsions with plant‐derived ingredients only, that is, proteins extracted from canola oil bodies, used as co‐emulsifiers with a canola lecithin, and to assess their suitability for food applications. Using the protein extract increases the chemical stability of rapeseed oil emulsions toward oxidation, based on the delay in conjugated diene formation under accelerated storage conditions, and favors pancreatic lipase activity. Bioaccessibility of rapeseed fatty acids is compared in lymph‐duct‐cannulated rats fed oil or emulsion. Fatty acid absorption by the intestine is increased by 78% when the oil is emulsified with canola proteins as co‐emulsifier: 28.7 mg mL^?1 versus 16.1 mg mL^?1 for oil (p < 0.05). In vitro lipolysis results are in overall agreement with fatty acid absorption in vivo. Practical Applications: Results obtained for rapeseed oil emulsified with canola proteins and phospholipids suggest that increased bioaccessibility of n‐3 polyunsaturated fatty acids could be offered in vegan food products.     

Oxidative stability and acceptability of camelina oil blended with selected fish oils

The effects of blending camelina oil with a number of fish oils on oxidative stability and fishy odour were evaluated. Camelina oil was found to be more stable than tuna oil, ‘omega‐3’ fish oil and salmon oil as indicated by predominantly lower ρ‐anisidine (AV), thiobarbituric acid reactive substances (TBARS) and conjugated triene levels (CT) during storage at 60 °C for 20 days (p < 0.05). Peroxide values (PV) were similar for all oils until Day 13 when values for camelina oil were higher. Values for blends of the fish oils (50, 25, 15, 5%) with camelina oil were generally between those of their respective bulk oils indicating a dilution effect. Camelina oil had a similar odour score (p < 0.05) to sunflower oil (9.2 and 9.6, respectively) indicating, as expected, an absence of fishy odours. In comparison, the fish oils had lower scores of 6.1 to 6.6 (p < 0.05) indicating mild to moderate fishy odours. Odour scores were improved at the 25% fish oil levels (p < 0.05) and were not different to camelina oil at the 15 or 5% levels (p < 0.05). Practical applications: Camelina oil is a potentially important functional food ingredient providing beneficial n‐3 PUFA. Oil extracted from Camelina sativa seeds contains greater than 50% polyunsaturated fatty acids of which 35‐40% is α‐linolenic acid (C18:3ω3, ALA), an essential omega‐3 fatty acid 1 . While EPA and DHA from fish oils are more potent nutritionally, they are less stable than ALA. This work evaluated innovative blends of fish oil with camelina oil for stability and acceptability. The results demonstrate that there is potential for use of blends of camelina oil with fish oils in food products, as the results show some benefits in terms of reduction of fishy odours. Such information could be valuable in relation to formulation of food products containing high levels of n‐3 PUFA from both plant and fish sources.     

Rectorite/thermoplastic polyurethane nanocomposites. II. Improvement of thermal and oil‐resistant properties

Organ‐rectorite/thermoplastic polyurethane (OREC/TPUR) nanocomposites were synthesized via melt intercalation. The dynamic mechanical properties by dynamic mechanical analysis (DMA), thermal and oil‐resistant properties were investigated. The results show that the storage modulus (E′), loss modulus (E″), and glass‐transition temperature (T_g) of the nanocomposites have an increase to some extent than those of pure TPUR. The thermal stability of nanocomposites was also studied in detail by thermal gravity analysis (TGA), which was higher than that of pristine TPUR matrix when the content of organic REC is at 2 wt %, and the decomposition temperature at 10% weight loss of OREC/TPUR is greatly increased up to 330°C from 315°C. Oil uptake of the composites is also significantly reduced in comparison with TPUR matrix, which is ascribed to the good barrier effect of nanosheets of OREC. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1165–1169, 2005     

Effect of olive fruit freezing on oxidative stability of virgin olive oil

Several studies have suggested that the phenolic fraction plays an important role during storage and therefore in the shelf life of virgin olive oil. This investigation examines the effect of freezing olives (–18 °C) before processing into oil on the transfer of the phenolic compounds into the subsequent oil, and the consequential changes in oxidative stability. Oil samples obtained from frozen olives (24 h at –18 °C), crushed with and without preliminary thawing, were compared to a control sample; both oils were obtained using a two‐phase low‐scale mill. The oxidative stability in different samples was assessed in terms of primary and secondary oxidation products as measured by peroxide values and oxidative stability index times, respectively. The quality of the oil samples was also checked through the percentage of free acidity and the phenolic content. Phenols were determined by both spectrophotometric assays (total phenols and o‐diphenols) and HPLC‐DAD/MSD. The antiradical capacity of the phenolic fraction was determined by DPPH and ABTS spectrophotometric tests. These analyses showed that thawing of olives before oil extraction led to a significant loss of oxidative stability and phenols; in contrast, samples obtained from frozen olives that were not thawed before crushing showed qualitative characteristics similar to control samples.