Storage stability evaluation of some packed vegetable oil blends

The physicochemical characteristics and minor component contents of blended oils packed in pouches in relation to starting oils used for blending were studied over a period of 6 mon at two storage temperatures and humidity conditions: 27°C/65% RH and 40°C/30–40% RH. Color, PV, FFA value, β-carotene content, tocopherol content, and oryzanol content of the oils were monitored at regular intervals. The color, PV (0.6–20.7 meq O₂/kg, FFA value (0.08–2.1%), tocopherol content (360–1700 ppm%), oryzanol content (460–2,000 mg%), and sesame oil antioxidants (400–2,000 mg%) were not changed in either the starting oils or their blends. Oils and oil blends containing a higher initial PV (18.9–20.7 meq O₂/kg) showed a slight reduction in value at 40°C, whereas oils having lesser PV of 5–10 showed a slight increase during the storage period. Among the minor components studied, only β-carotene showed a reduction, 8.9–60.2% at 27°C and 48–71% at 40°C, for the different oil blends studied. The observed results indicated that the packed oil blends studied were stable under the conditions of the study, and the minor components, other than β-carotene, remained unaltered in the package even at the end of 6 mon of storage.     

Thermodynamic phase behavior of fluoropolymer mixtures with supercritical fluid solvents

Cloud-point experimental data were presented at temperatures up to 260 °C and pressures up to 2,500 bar for poly(vinylidene fluoride) (PVDF) [M_w=180,000 and 275,000] in CO₂, CHF₃, CHClF₂, and dimethyl ether (DME). Also, phase behavior curves were shown for the PVDF [M_w= 180,000] in CO₂ with 1-propanol and 1-pentanol. Poly(vinyl fluoride) does not dissolve in CO₂ even at 215 °C and 2,500 bar, while poly(vinylidene fluoride) does dissolve in CO₂ at 220 °C and pressures of 1,700 bar. To dissolve poly(vinylidene fluoride) in dimethyl ether, pressures in excess of 200 bar and temperatures in excess of 165 °C are needed. The cloud-point behavior between the ternary PVDF [M_w=180,000]-CO₂-DME mixture shows a temperature range of 100–195 °C and pressure range of 350–1,360 bar by adding the 11, 29, and 60 wt% DME in cosolvent. The phase behavior for PVDF [M_w=180,000]-CHF₃-9, 19, and 40 wt% CHClF₂ system shows a temperature at below 200 °C and pressure up to 1,700 bar. The effect of CHClF₂ as a cosolvent for PVDF [Mw=275,000] in CO₂ decreased with the pressure increasing 10, 26, 40 and 61 wt% of cosolvent (CHClF₂) contents. Also, the effect of 15 and 40 wt% DME for the PVDF [M_w=275,000]-CHF₃ mixture shows temperature ranges of 120–206 °C and pressures up to 1,570 bar.     

Utilization of high-melting palm stearin in lipase-catalyzed interesterification with liquid oils

Palm stearin with a melting point (m.p.) of 49.8°C was fractionated from acetone to produce a low-melting palm stearin (m.p.=35°C) and a higher-melting palm stearin (HMPS, m.p.=58°C) fraction. HMPS was modified by interesterification with 60% (by weight) of individual liquid oils from sunflower, soybean, and rice bran by means of Mucor miehei lipase. The interesterified products were evaluated for m.p., solid fat content, and carbon number glyceride composition. When HMPS was interesterified individually with sunflower, soybean or rice bran at the 60% level, the m.p. of the interesterified products were 37.5, 38.9, and 39.6°C, respectively. The solid fat content of the interesterified products were 30–35 at 10°C, 17–19 at 20°C, and 6–10 at 30°C, respectively. The carbon number glyceride compositions also changed significantly. C₄₈ and C₅₄ glycerides decreased remarkably with a corresponding increase of the C₅₀ and C₅₂ glycerides. All these interesterified products were suitable for use as trans acid-free and polyunsaturated fatty acid-rich shortening and margarine fat bases.     

Amine-terminated aromatic and semi-aromatic hyperbranched polyamides: synthesis and characterization

A facile synthetic approach to aromatic and semiaromatic amine-terminated hyperbranched polyamides via direct polymerization of triamine (B₃) with different diacid chlorides (A₂) was explored. An aromatic triamine, 1,3,5-tris(4′-aminophenylcarbamoyl)benzene (TAPCB), was synthesized and monomers were characterized by elemental analysis, FTIR, ¹H and ¹³C NMR spectroscopy. Finally, the polycondensation reaction of TAPCB with terephthaloyl chloride (TPC), isophthaloyl chloride (IPC), sebacoyl chloride (SC) and adipoyl chloride (AC) resulted in the preparation of four hyperbranched polyamides i.e., HBPA 1, 2, 3 and 4, respectively. FTIR and ¹H NMR analyses confirmed the structures of the ensuing polymers and DB was found between 0.51–0.55. These thermally stable amorphous HBPAs were soluble in polar aprotic solvents at room temperature having glass transition temperatures (T_g) between 138–198 °C. Inherent viscosities (η_inh) and weight average molecular weights (M_w) were in the range of 0.27–0.35 dL/g and 1.3 × 10⁴–2.7 × 10⁴, respectively. Future prospects are envisaged.     

Use of nitrogen to improve stability of virgin olive oil during storage

Experiments were carried out to study the possibility of improving the stability of extra virgin olive oil by using nitrogen as a conditioner gas during storage. With this aim, virgin olive oil samples, obtained from Leccino and Coratina cultivars, were stored in the dark, in closed bottles conditioned with air or nitrogen at 12–20 and 40°C. Results indicated that the FFA percentage increased over 1% only when oils were stored at 40°C. The PV and the K ₂₃₂ value (light absorbance at 232 nm) of oils increased over the limit value allowed by European Union law when the bottles were only partly filled and air was the conditioner gas. The use of nitrogen as conditioner gas helped to avoid this risk during 24 mon of storage at 12–20°C. The total phenolic content of both cultivars oils decreased during storage because their oxidation protected the oils from autoxidation. The content of total volatile compounds in oils decreased continuously during storage at 12–20°C, whereas it increased over 10 (Coratina cv.) and 15 (Leccino cv.) mon and then diminished when the storage temperature was 40°C. The same behavior, i.e., increase then decrease, was ascertained for trans-2-hexenal. The hexanal content of oils increased continuously during storage because this compound is formed by the decomposition of the 13-hydroperoxide of linoleic acid.     

Thermophilic phospholipase A2 in the cytosolic fraction from the archaeon Pyrococcus horikoshii

Hyperthermophilic archaeon Pyrococcus horikoshii produced phospholipase A² in a cytosolic fraction. The enzyme displayed optimal activity at 90°C and pH 7 and preferentially hydrolyzed sn-2 fatty acids in the following order: linoleoyl> oleoyl>arachidoyl phosphatidylcholine. Phospholipase A₂ had similar activities toward l-α-1-palmitoyl-2-arachidoyl derivatives of phosphatidylcholine and phosphatidylethanolamine. Phospholipase A₂ activity was unaffected by the addition of 0.0001–1 mM calcium, but was inhibited slightly by the addition of 2–10 mM calcium. The activity was enhanced more than 5–18-fold in the presence of 3–20% (vol/vol) glycerol. The activity was unaffected by the addition of 1–5 mM EDTA or 0.01–20 mM dithiothreitol. A caldarchaetidic acid derivative having a molecular weight of 1544 disappeared upon incubation of the cytosolic fraction with total lipid. The phospholipase A₂ was difficult to purify by general chromatography because it existed as an aggregate. Electrophoresis was carried out using 10–15% polyacrylamide gels containing sodium dodecyl sulfate (SDS-PAGE). No activity of phospholipase A₂ activity was observed in the absence of proteins less than 19 kD in size, as fractionated by SDS-PAGE. Portions of this article were presented at the Biocatalysis Symposium at the 91st Annual Meeting and Expo of the American Oil Chemists’ Society in San Diego, CA, April, 2000.     

Lipase activity and fatty acid typoselectivities of plant extracts in hydrolysis and interesterification

Lipase fatty acid typoselectivities of Euphorbia characias latex and commercially available crude preparation of bromelain were determined in the hydrolysis of homogeneous triacylglycerols (TAG) and natural TAG mixtures. Their activities were compared to a commercially available crude preparation of papain. Under optimal lipolysis conditions at pH 8.0 and 10 min of incubation time, maximal activities were observed at 45, 55, and 50°C, respectively, for E. characias latex, crude bromelain, and crude papain. Commercially available crude preparations of bromelain exhibited very poor hydrolysis activity. Latex from E. characias, which contained 340 mg of dried material per milliliter of fresh latex, exhibited a high lipase activity and a short-chain fatty acid preference in the hydrolysis of homogeneous TAG. For all substrates, it showed a better activity than crude papain. Lipase fatty acid typoselectivities of crude bromelain and crude papain also were studied in interesterification reactions of tributyrin with a series of homogeneous TAG. Experiments showed that crude bromelain [water activity (A _w )∶ 0.21] had no activity in interesterification. Regarding reactions with crude papain (A _w ∶ 0.55), yields of newly formed TAG decreased with increasing chain length of TAG, except for the reaction with trimargarin. For interesterification of tributyrin with unsaturated TAG, triolein reacted faster than polyunsaturated TAG. During these interesterification reactions, the proportion of new TAG with two butyroyl residues was higher than new TAG with only one butyroyl residue. This phenomenon was more pronounced for reactions with long-chain TAG.     

Effect of interesterification on the structure and physical properties of high-stearic acid soybean oils

Triglyceride structures of genetically modified soybean oils high in stearic acid were determined by high-pressure liquid chromatography, and their physical properties were assessed by dilatometry and dropping point. In their natural state, these oils lack sufficient solids at 10–33°C to qualify as margarine oils. However, after random interesterification, soybean oil containing 17% stearic acid shows a solid fat index (SFI) profile and dropping point closely matching those of a liquid margarine oil. Other oils, with stearic acid contents in the range of 20–33%, showed appreciable SFI values at 10°C but lacked sufficient solids at 21.1–33.3°C. After random interesterification, these oils also exhibited SFI profiles suitable for soft tub margarine, and their drop points increased from 18–19°C to 36–38°C.     

Comparison of the unperturbed dimension of polystyrene for endothermal and exothermal heats of dilution within the same system

Light scattering measurements for two samples of polystyrene (I, M_w = 2.15 × 10⁵; II, M_w = 2.5 × 10⁶) were performed in the iso-refractive mixed solvent dimethoxymethane-diethyl ether. For sample I the temperature dependence of the second osmotic virial coefficient A₂ was determined for three constant compositions of the mixed solvent. In the range ?30° to +25°C the three curves run practically parallel and exhibit a maximum at approximately ?10°C. For the volume fraction of 0.7 diethyl ether in the mixed solvent, an endothermal theta-temperature θ₊ was found at ?27.0° ± 1.5°C and θ_?, the exothermal theta-temperature, at ?5.0 ± 1°C. The investigation of sample II in the abovementioned solvent confirmed the observed θ_?-temperature and displayed a higher exothermicity compared with I. Similarly to the temperature variation of A₂, the chain dimensions of II, determined from the angular dependence of the scattered light, run through a maximum. The unperturbed dimensions in the mixed solvent are found to be: $\text{r}{}_{\mathrm{w}}\text{= 448 ± 5}\text{A}\text{?}$ at θ₊ = ?27°C and $\text{r}{}_{\mathrm{w}}\text{= 443 ± 5}\text{A}\text{?}$ at θ_? = ?5°C, as compared with $\text{r}{}_{\mathrm{w}}\text{= 420 ± 10}\text{A}\text{?}$ at θ₊ = +33°C in cyclohexene. The inter-relation of the chain expansion coefficient and A₂ is quantitatively described by the Zimm-Stockmayer-Fixman equation over the entire range of heats of dilution.     

Protein concentrate and adhesives from meat and bone meal

Defatted meat and bone meal (MBM) was prepared by the removal of extractable fat with isopropyl alcohol. Proteins in the defatted MBM were extracted with 0–4% NaCl concentrations with 0.05% CaCl₂ or 0.05% MgCl₂ at pH 5.5–6.6 for 1 h at 50°C and precipitated at pH 4.0–4.5. By using the salt extraction procedure, MBM protein concentrate (MBMPC) (32 g) was obtained from defatted MBM (100 g). Recovery of protein was dependent on the extraction temperature employed; recovery values ranged from 33.2 to 51.4%. At 4% NaCl concentration, MgCl₂ increased protein solubility by 30%, compared to the control. The adhesiveness of MBMPC at various pH values ranging from 5.0 to 9.0 was investigated. At pH 6.0–8.0, adhesiveness of MBMPC showed the highest value (78.2 kg). The adhesiveness increased linearly as the MBMPC concentration increased up to 20% with respect to temperature for MBMPC adhesiveness, the greatest adhesiveness was in the range of 70 to 90°C. Improved adhesiveness and water resistance were observed with 0.05% glutaraldehyde treatment.     

Synthesis and characterization of poly(arylene ether) containing cyanate ester networks

A series of bisphenols containing ether linkage were prepared from halo phenol/dihalo compound and dihydroxy compounds in the presence of K₂CO₃. The bisphenols were transformed to cyanate esters by treatment with cyanogen bromide using triethyl amine catalyst. The structure of all the five bisphenols and the cyanate esters were structurally confirmed by FT-IR, ¹H-NMR and ¹³C-NMR spectral methods and elemental analysis. The cyanate esters were cured at 100 °C (30 min) → 150 °C (30 min) → 200 °C (60 min) → 250 °C (3 hr). The thermal properties of the cured resins were studied by DSC and TGA. DSC analysis shows that these cyanate esters exhibit T _g in the range of 203–234 °C. The CE(c) has the highest glass transition temperature. The cyanate ester CE(e) shows the lowest T _g which is due to its asymmetric structure. The initial degradation temperature of the cured resins was found to be in the range of 324–336 °C. The Limiting Oxygen Index (LOI) value, determined by Van Krevelen’s equation, is in the range of 35.5–38.7.     

Weak gels of fat crystals in oils at low temperatures and their fractal nature

The formation of fat crystal gels in soybean oil has been studied by sedimentation in a low concentration region at 10–25°C. At 10°C, weak gels were formed with 1% crystals, and no gels formed at concentrations of 2–5%. At temperatures of 15–25°C, no gels were formed at concentrations of 1–5%, and samples sedimented. Stronger gels of fat crystals were formed with ∼10% fat crystals at all temperatures examined. Formation of weak gels is a consequence of the fractal nature of fat crystal aggregates and sediments. At low temperature, the interaction is weak. The fractal dimension is then high, and the floc size is large for low crystal concentrations. These large flocs form a three-dimensional network that act as a weak gel and withstand gravitational force. When the temperature is increased, the fat crystal interaction becomes stronger, fractal dimension decreases, and floc size decreases. Smaller flocs have a higher density, pack more easily, and sediment. Similar effects are observed when the concentration of fat crystals is increased at low temperature due to a decrease in floc size.     

Hyperbranched Polymers Containing Cyclopentadienyliron Complexes

A number of hyperbranched polymers containing cyclopentadienyliron moieties were prepared using the A₂+B₃ method. The A₂ compounds used were common diols, dithiols or dichloroarenecomplexes. B₃ compounds included either prepared star-shaped molecules or a purchased triol. The effect of the reaction conditions on the properties of the products was probed. Analysis of the prepared polymers was conducted using ¹H and ¹³C NMR, viscometry, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Viscometry values were generally found to be low, in the range of 0.175–0.300 dl/g. TGA showed losses starting at approximately 230°C and ending at 280°C, corresponding to the decomposition of the cyclopentadienyliron moiety. Degradation of the polyether backbone was found to occur starting at 390–567°C. Glass transition temperatures were found to be between 60 and 134°C, whereas melting temperatures ranged from 155 to 190°C.     

Volatile compounds in oils after deep frying or stir frying and subsequent storage

Soybean oil (900 g) was heated by deep frying at 200°C for 1 h with the addition of 0, 50, 100, 150 and 200 mL water, and then stored at 55°C for 26 weeks. Soybean oil, corn oil and lard were heated by stir frying and then stored at 55°C for 30 weeks. The volatiles and peroxide values of these samples were monitored. All samples contained aldehydes as major volatiles. During heating and storage, total volatiles increased 260-1100-fold. However, aldehyde content decreased from 62–87% to 47–67%, while volatile acid content increased from 1–6% to 12–33%; especially hexanoic acid which increased to 26–350 ppm in the oils after the storage period was completed. Water addition to the oils heated by deep frying tended to retard the formation of volatile compounds. The total amount of volatile constituents of lard heated by stir frying increased more during storage than that of corn oil or soybean oil. Peroxide values did not reflect the changes of volatile content in the samples.     

Oxidation of Corn Oils with Spiked Tocols

Stripped corn oils with added tocopherols and tocotrienols, at concentrations between 100 and 5,000 ppm, were used to evaluate antioxidant activity of these tocol compounds. The formation of lipid hydroperoxides, measured as peroxide value (PV), was accelerated at 60 °C in the dark for 5 days. Resistance to oxidation as induction period (IP) was also measured using an oxidative stability instrument (OSI) at 100 °C. For PV inhibition, the oils containing α-tocols exhibited decreasing effectiveness with increasing concentration. At day five, samples with 100 ppm α-tocols had the lowest PVs of about 40 mequiv/kg and samples containing 5,000 ppm had the highest values, ranging from 150 to 200 mequiv/kg. At concentrations above 700 ppm of α-tocols, there was an inversion of antioxidative properties as α-tocols promoted lipid oxidation. The opposite concentration effect was observed with δ-tocols and γ-tocotrienol (T3) for which antioxidant effectiveness increased with concentration. OSI-IP hour at 100 °C increased with increasing tocol concentrations for all tocol homologs, although with diminishing effectiveness at greater than 700 ppm. The α-tocols were less effective in extending the IP (~9 h at 5,000 ppm) than the δ-tocols and γ-T3 (13–14 h at 5,000 ppm). Therefore, the antioxidant or prooxidant activities of different tocols are different and the outcomes are different depending on the evaluation methods used.     

Thermal analysis of palm mid-fraction,cocoa butter and milk fat blends by differential scanning calorimetry

Commercial samples of anhydrous milk fat (AMF), Ivory Coast cocoa butter (CB) and palm mid-fraction (PMF) were blended in a ternary system. The melting characteristics of the blends were studied by differential scanning calorimetry (DSC). Results suggest that in the studies of interaction involving more than two fats, partial area (A_i) under the melting peak should be converted to partial enthalpy (ΔH_i) rather than to solid fat index. The ΔH values of the blends decreased as the amount of AMF was increased and increased as the amount of CB was increased. In general, the effect of PMF was less pronounced compared to the effect of the other two fats. Eutectic effects within the ternary system could be detected by measuring the deviation of melting enthalpy by DSC, and from the corresponding values that were calculated for the thermodynamically ideal blends. The deviation reached a maximum when the amount of AMF was about 33%. On the binary line of CB/PMF, the eutectic effect was maximum at about 50–75% PMF. The interaction effect in the system was more noticeable at 30 and 20°C than at lower temperatures. Evaluation at 30°C was preferred because both the effect of AMF in the ternary system and the effect of PMF on the binary line were more readily observed.     

Differential Scanning Calorimetry Analysis of Goat Fats: Comparison of Chemical Composition and Thermal Properties

The physical–chemical properties, fatty acid composition and thermal properties of goat subcutaneous (SF), tallow (TF) and intestinal (IF) fats were determined. SF differed from other fat types with respect to its lower melting (41.6 °C), lower saponification (190.3 mg KOH/g) and higher iodine (40.4) values as compared to those of other fats. Goat fat types contained palmitic acid (C_16:0), stearic acid (C_18:0), oleic acid (C_18:1ω9) and linoleic acid (C_18:2ω6) as the major components of the fatty acid composition (23.06–23.52, 22.95–39.03, 21.94–36.16 and 1.96–2.22%, respectively). A differential scanning calorimetry (DSC) study revealed that two characteristic peaks were detected in both crystallization and melting curves. Major peaks (T _peak) of TF and IF were similar and determined as 34.02–35.24 and 9.95–10.72 °C, respectively for the crystallization peaks and 15.11–18.26 and 50.70–52.76 °C, respectively for the melting peaks in the DSC curves; but those of SF (27.14 and 4.36 °C for crystallization peaks and 8.39 and 44.93 °C for melting peaks) differed remarkably from those of other fat types.     

Relationship between rancimat and active oxygen method values at varying temperatures for several oils and fats

Determination of oxidative stability of different edible oils, fats, and typical fat products was made using the Rancimat method and the active oxygen method. Induction periods (IP) were recorded under controlled conditions at 110, 120, and 130 ± 0.1°C for all products and over a range of 100–160°C for selected fats. A general oil stability evaluation industrial shortenings and vanaspati to be the most stable fats, with IP ranging from 10.00 to 15.47 h. Margarine and butter samples (IP, 4.98–6.04 h) were also found to show fair oxidative stability. Among the extracted and open-market salad-grade cooking oils, rapeseed oil (IP, 4.10 h) and soybean oil (IP, 4.00 h) showed the highest oxidative stability, whereas Salicornia bigelovii oil (IP, 1.40 h) was the least stable. The induction periods of typical fat products ranged from 2.59 to 9.20 h. CV for four determinations were <5.2% for shortening and vanaspati products and <4.3% for various vegetable oils, margarine, butter, and typical fat products. Rancimat IP values obtained at 110, 120, and 130°C were 40–46, 20–25, and 9–13% of active oxygen method values, respectively, corresponding to a decrease in Rancimat IP by a factor of 1.99 with each 10°C increase in temperature. Similarly, in the temperature range 100–160°C, an increase of 10°C decreased the Rancimat IP by a factor of 1.99     

The acetolysis of glycerides. I. Preliminary investigation and approximate kinetics

Below 120°C., direct acidolysis of fats by acetic acid is vanishingly slow, the observed reaction being a slow hydrolytic fat splitting to partial glycerides followed by a rapid acetylation. Water is an essential reactant, and strong acid catalysis of the reaction is effective only in its presence. The reaction is unimolecular with respect to the acid catalyst, and probably also to the ester linkages, but molecularity falls below unity with respect to water, which has strong effects on acid strengths in an acetic acid medium. The reaction velocity has a temperature coefficient of 1.6 per 10°C. over the range 77–118°C. Using a three-fold weight of 98% acetic acid, 1% of catalyst, and 12–24 hours' reaction at 100–118°C., fat splits of around 90% can be attained.     

Physicochemical and Oxidative Changes in Sonicated Interesterified Soybean Oil

The effect of power ultrasound on physicochemical properties and oxidative stability of an interesterified soybean oil (IESBO) was investigated. IESBO was crystallized at 32 °C and sonicated for 10 s with acoustic power of 101 W. The sonicated IESBO was tested for melting behavior and chemical composition and compared to those of non sonicated IESBO to determine physical and chemical changes originated as a consequence of sonication. Application of power ultrasound affected the melting behavior of the crystallized fat and did not affect its chemical composition. Oxidation stability of the sonicated IESBO was measured using peroxide value (PV) and compared to that of non sonicated IESBO and liquid soybean oil (SBO) when stored at 25 °C for 105 days followed by storage at 40 °C for 42 days. Power ultrasound did not cause accelerated oxidation in SBO or IESBO until they were highly oxidized (PV > 10 mequiv/kg). At high levels of oxidation, non‐sonicated IESBO had significantly higher PV than sonicated IESBO, while non‐sonicated SBO had significantly lower PV than sonicated SBO.