Effect of extraction techniques on the chemical composition and antioxidant activity of Eucalyptus camaldulensis var. brevirostris leaf oils

 The volatile oil compositions of Eucalyptus camaldulensis var. brevirostris leaves obtained by hydrodistillation (HD) and supercritical fluid extraction methods (SFE) were analysed qualitatively and quantitatively by GLC-MS. Ninety different components were separated and most of them identified. In both extracts the main constituents were found to be β-phellandrene (8.94 and 4.09%), p–cymene (24.01 and 10.61%), cryptone (12.71 and 9.82%) and spathulenol (14.43 and 13.14%). The yield of the monoterpene hydrocarbons in HD oil (0.288 g/100 g fresh leaves) was slightly higher compared with that in the SFE extract (0.242 g/100 g fresh leaves). The SFE extract possessed higher concentrations of the sesquiterpenes, light oxygenated compounds and heavy oxygenated compounds than the HD oil. The relationship between the antioxidant activity and chemical composition of the extracted oils was investigated. The significant amounts of p–cymen-7-ol and thymol are responsible for the antioxidative activity of both extracts. The concentration of both compounds, but especially that of p–cymen-7-ol (2.25%), is higher in the SFE extract. This corresponds with the higher antioxidative activity of the SFE compared with the HD extract. p–Cymen-7-ol, a compound newly identified in leaves of Eucalyptus species, exhibited superior antioxidant activity in comparison with that of butylated hydroxyanisole. Received: 30 April 1998     

Antioxidant and antimicrobial activities of the methanol extracts from pummelo (Citrus grandis Osbeck) fruit albedo tissues

The present study was conducted to evaluate the antioxidant and antimicrobial properties of methanol (100 and 80% aqueous) extracts of pummelo fruits albedo (Citrus grandis Osbeck). The antioxidant and antibacterial activity for crude extracts and isolated compounds were evaluated using free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) and Paper disc diffusion method. A 100% Methanol (MeOH) extract was steeped in water at different pH levels and partitioned with ethyl acetate (EtOAc) to give basic, acidic, neutral, and phenolic fractions. The neutral extract was found to possess maximum antioxidant and antibacterial activity. Thereafter, neutral extract was carried out on a silica gel column and eluted with hexane:EtOAc:acetone and preparative TLC (PTLC) to give oil buntan compound, linoleic acid methyl ester, β-sitosterol, sigmasterol, limonin, nomilin and meranzin hydrate were isolated. While, 80% MeOH extract was fractionated also using a silica gel column and PTLC to give isomeranzin hydrate, p-coumaric acid and caffeic acid compound. The extract concentration providing 50% inhibition (IC₅₀) was as follows; oil buntan compound 95 μg/mL, caffeic acid 45 μg/mL, p-coumaric acid 105 μg/mL, limonin + nomilin (mixture) 135 μg/mL was lower than that of synthetic antioxidant butylated hydroxyanisole (BHA) 40 μg/mL. The inhibitory zone (mm) of bacteria tested was 2.9–4.1 mm caffeic acid and 11.6–15.1 mm p-coumaric acid.     

Effect of Ensilaging and Organic Solvent Treatment on Activity of Proteases from Chicken Intestine

Studies were carried out to assess the extractability of proteins from chicken intestine and to determine the activity of proteases in crude extract. Further, the activity of proteases was evaluated in acid and fermented chicken intestinal silage as well as in organic solvent-treated intestinal samples. Extractability of proteins was in the range of 3.85–4.06 mg/ml and was not affected (p ≥ 0.05) by the four different extractants, viz., distilled water, phosphate buffer, and 1% potassium chloride with or without 0.1 M Na₂EDTA. The specific activity of acidic and alkaline proteases were in the range of 4.78–7.26 and 19.31–24.07 units, respectively, and was not affected (p ≥ 0.05) by the type of extractant used. The pH profile for activity showed higher activity in the alkaline pH range. Addition of acid or ingredients for fermentation reduced the extractability of protein significantly (p ≤ 0.05). During storage of silage, the reduction in enzyme activity was higher in acid silage compared with fermented silage. Treatment of chicken intestine with organic solvents enhanced the enzyme activity and higher increase was observed with isopropyl alcohol-treated intestine. During storage of solvent-treated powders up to 3 months, the activity of proteases reduced in all the solvent-treated samples highest being in acetone-treated powder.     

Optimization of supercritical CO2 extraction of phytosterol-enriched oil from Kalahari melon seeds

Supercritical carbon dioxide (SC-CO₂) extraction of oil from Kalahari melon seeds was investigated in this study. Response surface methodology was applied to model and optimize the extraction, namely pressure (200–400 bar), temperature (40–80 °C), and supercritical fluid flow rate (10–20 mL/min). Well-fitting models were successfully established for oil recovery (R ² = 0.9672) and phytosterol concentration (milligrams per 100 g; R ² = 0.8150) through multiple linear regressions with backward elimination. The effect of supercritical fluid flow rate was the most significant (P < 0.05) factor that affected oil recovery but this factor had no significant (P > 0.05) effect on phytosterol concentration. The optimal processing conditions for oil recovery and phytosterol concentration were pressure of 300 bar, temperature at 40 °C, and supercritical fluid flow rate of 12 mL/min. These optimal conditions yielded a 76.3% oil recovery and 836.5 mg/100 g of phytosterol concentration. The oil content in the Kalahari melon seeds as estimated by Soxhlet extraction was around 30.5/100 g. The phytosterol concentration in the oil extracted with SC-CO₂ extraction was 94% higher than that obtained with solvent extraction.     

Simultaneous Determination of Sodium, Potassium, Manganese and Bromine in Tea by Standard Addition Neutron Activation Analysis

Standard addition method was applied for neutron activation analysis of tea leaves. Four brands of tea leaves were analyzed for its Na, K, Mn, and Br contents by this method. The Na, K, Mn, and Br concentrations were found to be in the 90–120 μg/g, 1.8–2.1% w/w, 150–500 and 3–7 μg/g ranges, respectively. The extraction efficiency of these elements, during the infusion, was calculated by analysis of tea leaves before and after the infusion process. It was observed that about 90% of the Na, K, and Br elements were extracted to water during the infusion process. The drinking tea is a rich source of Mn (despite of an extraction efficiency of 50% for this element).     

Comparison of Physicochemical and Antioxidant Properties of Egg-White Proteins and Fructose and Inulin Maillard Reaction Products

The Maillard reaction (MR), involving the condensation of a carbonyl group of reducing sugar and an amino group of protein, can change functional properties of proteins. In this study, chemical characteristics and functional properties of glycosylated albumin, ovomucoid, and lysozyme (egg proteins) and casein with fructose or inulin through the MR were evaluated. The protein and sugar mixtures were heated at 60 °C and 79% relative humidity for 3 days. Chemical characteristics of the egg protein–sugar Maillard reaction product (MRP) mixtures were evaluated by fluorescence development, absorbance intensity (at 420 nm), and color change. Functional properties of the protein–sugar MRP mixtures were also evaluated, including emulsifying activity, emulsion stability, and antioxidant activity. The protein–sugar conjugates were found to have significant (p < 0.05) changes compared to the controls (unheated protein–sugar samples) in color, fluorescence, and absorbance intensity. All protein–sugar MR models exhibited a change in emulsifying activity, with Csn–Fru MRP displaying the greatest significant (p < 0.05) improvement. In addition, all protein–sugar MR models exhibited changes in emulsion stability, with Ovo/Inu MRP displaying the greatest significant (p < 0.05) change. All protein–sugar MR models exhibited great scavenging activity towards 1,1-diphenyl-2-picryl-hydrazyl radical at MRP concentrations of 0.2, 0.5, and 1.0 mg/mL. With the exception of the 0.2 mg/mL MRP concentration, there was a significant difference (p < 0.05) between the heated protein–fructose and the heated protein–inulin MRPs.     

Effect of a Polyphenol–Vacuum Packaging on Lipid Deterioration During an 18-Month Frozen Storage of Coho Salmon (<Emphasis Type="Italic">Oncorhynchus kisutch</Emphasis>)

A packaging system combining a polyphenol-rich film and vacuum (PPRF–VP) was applied to farmed coho salmon (Oncorhynchus kisutch) muscle for an 18-month storage (−18 °C). For it, two different concentrations of polyphenol compounds (namely, p-coumaric and ferulic acids) obtained from a barley husk extract were applied (PPRF–VP conditions) and compared to vacuum packaging without polyphenol presence (vacuum control; VP condition) and to packaging in the absence of vacuum and polyphenols (control; CP condition). The study was addressed to lipid hydrolysis and oxidation development and to lipid changes related to nutritional value. Both PPRF–VP conditions provided an inhibitory effect (p < 0.05) on conjugated diene and fluorescent compound formation in frozen salmon. Compared to CP condition, vacuum packaging (PPRF–VP and VP conditions) led to lower (p < 0.05) peroxide and anisidine values and to an inhibitory effect (p < 0.05) on α- and γ-tocopherol losses. No effect (p > 0.05) of polyphenol presence and vacuum packaging could be inferred on free fatty acid formation (hydrolysis development) and on polyunsaturated fatty acid retention (polyene index assessment). A low rancid odour development was observed in all kinds of fish samples, this being lower (p < 0.05) in fish kept under vacuum (PPRF–VP and VP) conditions.     

二氧化碳膨胀乙醇提取香樟精油的工艺研究

本研究尝试采用一种新型的绿色溶剂二氧化碳膨胀乙醇(CO2-Expanded Ethanol, CXE)从香樟叶中提取精油,并在精油的化学组成,抗氧化活性和抑菌活性方面,与常规的水蒸气蒸馏(HD)、有机溶剂提取(OSE)以及超临界二氧化碳提取(SFE)进行综合对比研究。结果表明,CXE提取油的得率为1.35%,高于超临界二氧化碳提取油的1.14%。气相色谱-质谱(GC-MS)联用分析结果显示,CXE提取油中含氧单萜类化合物较少,而倍半萜烯类化合物高于其他三种方法提取油,含量为2.49%。抗氧化活性试验结果表明,CXE提取油对DPPH自由基的清除率为82.42%,对ABTS自由基的清除能力为85.88%,活性均高于其它三种方法提取油。通过微量稀释法测定了精油抑菌活性,CXE提取油对白色念珠菌的MIC值为39 μg/mL,对黑曲霉的MIC值为19.5 μg/mL,表明CXE提取油对真菌呈现较高的抑制活性。综上所述,CXE提取过程隔氧、低温,可开发成为一种提取高品质植物精油的新方法,具有一定的应用前景。     

Optimization of Edible Oil Extraction from Ofada Rice Bran Using Response Surface Methodology

Effects of roasting temperature and duration on yield and quality (free fatty acid, peroxide value, color) of oil extracted from ofada rice bran was studied using response surface methodology. Roasting temperature and duration were 160, 170, 180, 190, and 200 °C and 5, 10, 15, 25, and 35 min respectively. Data were analyzed by ANOVA and regression analysis. The oil yield ranged between 11.31% and 14.4%, free fatty acid (7.10–12.75%), peroxide values (8.25–13.25 mEq/kg) and color (1.51–1.58 abs). The treatments have significant effects on oil yield, free fatty acid, peroxide values, and color at p < 0.05. Coefficient of determination R ² of oil yield, free fatty acid, color, and peroxide value models were 0.79, 0.91, 0.99, and 0.99 respectively. Optimum temperature and duration of roasting were 190 °C and 10.75 min, respectively. This combination gave 14.45% oil yield, 5.80% free fatty acid, 8.25 mEq/kg peroxide values and 1.51 abs oil color. Desirability of optimization was 0.99.     

Multielement analysis of Chinese tea (Camellia sinensis) by total-reflection X-ray fluorescence

 Total-reflection X–ray fluorescence (TXRF) was used for the simultaneous determination of 15 elements in tea samples which were produced either by acid digestion or acidified infusion of tea leaves (Camellia sinensis). The accuracy and precision of the method were checked by its application to a certified reference material (GBW 08505 : tea). A variety of 39 tea samples of different kinds and/or qualities produced in different regions of China were analysed. The range and mean of the concentrations of elements in the tea leaves (0.1–30.000 μg g^–1) and their solubility in infusions (0.5–85%) were determined and the influence of the origin, type and quality of the tea samples was studied. In some tea leaves produced in a Se-rich region, the content of Se was found to be very high (up to 7.5 μg g^–1), in contrast to a concentration of only about 0.1 μg g^–1 Se in most of the tea leaves examined. Received: 27 January 1998     

Protective effects of loquat (Eriobotrya japonica) leaves against ethanol-induced toxicity in HepG2 cells transfected with CYP2E1

Hepatoprotective effects of loquat (Eriobotrya japonica) leaves were investigated in HepG2 cells overexpressing CYP2E1. When compared to cells treated with 200 mM ethanol alone, a concentration-dependent increase in cell viability was observed in the cells pretreated with 40 and 80 μg/mL of 5% ethanol extract (EJE) of loquat leaves (23 and 36%, respectively). Also, pretreatment with EJE lead to a decrease in intracellular reactive oxygen species formation and an increase in hepatic antioxidant activity. These results suggest that EJE attenuates oxidative stress by improving antioxidative potentials, which contribute to this herb’s protective profile against ethanol-induced toxicity in vitro.     

Evaluation of Irradiation and Heat Treatment on Antioxidant Properties of Fruit Peel Extracts and Its Potential Application During Preservation of Goat Fish <Emphasis Type="Italic">Parupenaeus indicus</Emphasis>

The quenching capacities of Vitus vinifera seed extract, Citrus limon peel extract, Punica granatum peel extract, and Citrus sinensis peel extract were studied together with their antioxidant activity in goat fish (Parupenaeus indicus). The functionality of the extracts was evaluated using β-carotene-linoleic acid model system, reducing power assay, DPPH, hydroxyl, and nitrite radical scavenging assay. V. vinifera and P. granatum extract demonstrated best radical scavenging potential in all multifunctional antioxidant assays. Radical scavenging activity measured by electron paramagnetic resonance against a stable radical 1,1,-diphenyl-2-picrylhydrazil revealed radical peaks of lower intensity in antioxidant-infused samples. Compounds possessing antioxidant properties were identified from purified fruit extracts by GC–MS analysis. Treatments with these extracts increased the stability of irradiated goat fish against lipid oxidation. TBARS values for irradiated control was 4.26 ± 0.10, whereas it was 2.44 ± 0.14, 2.97 ± 0.01, 2.93 ± 0.03, 3.89 ± 0.05, and 4 ± 0.01 mg of MDS per kilogram fish for BHA, P. granatum peel, V. vinifera seed, C. sinensis peel, and C. limon peel extract-treated samples, respectively. This study also elucidated the relationship between heating temperature and irradiation dose on the antioxidant activity of extracts. Maximum antioxidant activity was observed at 150 °C heated and 10-kGy irradiated extracts. These results suggest that fruit peels will be a potential material for extracting antioxidants.     

Antioxidant activity of Egyptian Eucalyptus camaldulensisvar. brevirostrisleaf extracts

Leaves from Eucalyptus camaldulensis var. brevirostris trees, planted in the Nile delta in Egypt, were examined for the antioxidant activity of their nonvolatile compounds. The extracts obtained by ethanol digestion and by supercritical fluid extraction (SFE; CO₂ with 15% ethanol) showed the most promising antioxidative activities. In order to identify the most active compounds, both extracts were subjected to a semipreparative reversed‐phase HPLC separation, the main fractions were collected, tested for antioxidative activity and analysed by different chromatographical and spectroscopical methods for identification of the most relevant compounds. Gallic and ellagic acid were found to be the prevailing antioxidants in the ethanolic extract. The main two compounds of the SFE extract with antioxidative activity revealed to be flavones. To a high degree of probability they were identified as 5‐hydroxy‐7,4′‐dimethoxy flavone and 5‐hydroxy‐7,4′‐dimethoxy‐8‐methyl flavone, respectively. The extracts obtained by ethanol digestion were dried and administered to rats for toxicity evaluation (up to 3 g/kg body weight). No mortality was observed which indicates a very low lethality of the tested extract.     

Pilzhemmende Wirkung von Zedernholzextrakt und Hibaöl auf holzständige Schimmelpilze

Ceratocystis fimbriata , Penicillium glabrum und Trichoderma harzianum in Malzextraktbouillon aufgezeigt. In beiden L?sungen war β-Thujaplicin als bekannte pilzhemmende Substanz nachzuweisen, wobei die Konzentrationen bei 2,5 mM (Zedernholzextrakt) und 165 mM (Hiba?l) lagen. Weitere Ergebnisse in diesem Medium zeigten, da? offensichtlich durch die Eigenschaften des Hiba?ls eine Schw?chung der pilzhemmenden Eigenschaft des β-Thujaplicins erfolgte, wohingegen im Zedernholzextrakt weitere pilzhemmende Substanzen vorzuliegen schienen. Auch konnte die pilzhemmende Aktivit?t von Hiba?l und Zedernholzextrakt gegen die genannten Schimmelpilze auf Kiefernholz best?tigt werden, wobei die Wirkung des Hiba?ls wesentlich ausgepr?gter war.

---

Ceratocystis fimbriata , Penicillium glabrum, and Trichoderma harzianum could be demonstrated in malt extract broth. In both solutions, β-thujaplicin as a known antifungal substance could be detected. The concentrations were 2.5 mM (red cedar heartwood extract) and 165 mM (hiba oil). Further results using this growth medium showed that the antifungal activity of β-thujaplicin in hiba oil was obviously decreased due to properties of the oil, whereas other antifungal substances seemed to be present in the cedar extract. Furthermore, the antifungal activity of hiba oil and red cedar heartwood extract could be confirmed on pine wood. In this case, the effect of the hiba oil was much more pronounced.

     

Effects of Soy and Corn Flour Addition on Batter Rheology and Quality of Deep Fat-Fried Shrimp Nuggets

In this paper, the effects of soy and corn flour (5 and 10% w/w) addition to the batter formulation on the quality of deep fat-fried shrimp nuggets were evaluated. Rheological properties of batters, coating pick-up, moisture content, and oil content of the samples were determined. Shrimp nuggets were fried at 150 °C, 170 °C, 190 °C, for 1, 2, 3, 4, and 5 min. The coating pick-up, oil and moisture content were found to be directly proportional to batter viscosity. All batters were found to show shear thinning behavior by exhibiting flow behavior index ≤ 1. The batters were modeled as power law fluids. Batter formulation, frying time, and temperature significantly (p < 0.01) affected moisture and oil content of shrimp nuggets. Soy flour added batters provided the highest consistency index, 7.595 and 10.635 Pa.sⁿ for 5% and 10% soy flour added, respectively. Soy flour was found to be an effective ingredient in decreasing oil content of fried nuggets. Batters containing 5% corn flour showed the lowest moisture content and the highest oil content among all the formulations. The mean moisture and fat content of shrimp nuggets coated with batter contained 10% soy and 5% corn flour, fried at 190 °C, for 5 min were 0.59 ± 0.022, 0.480 ± 0.029 and 0.149 ± 0.035, 0.346 ± 0.024 (g/g db), respectively.     

Effects of Cultivar and Drying Method on Color,Pasting and Sensory Attributes of Instant Yam (<Emphasis Type="BoldItalic">Dioscorea rotundata</Emphasis>) Flours

Effect of cultivar (Efuru and Abuja) and drying method (cabinet and foam mat) on color, pasting, and sensory properties of instant pounded yam flours was investigated. Color (L*, a*, b*) values of fresh and dried flour samples were measured, and deltachroma (∆C), color difference (∆E), and hue angle were calculated. Pasting properties of flour and sensory attributes of fresh and reconstituted flour were determined. Foam density of yam pastes decreased from 0.97 g/cm³ to between 0.362–0.538 and 0.308–507 g/cm³ for cultivars Abuja and Efuru, respectively. Foam-mat dried flour showed higher L*, ΔC, ΔE, and hue angle but lower a* and b* values. Peak viscosities of cabinet and foam-mat dried Abuja and Efuru were 217, 304, 377.42, and 316.50 RVU, respectively. Sensory attributes of reconstituted foam-mat dried Abuja and fresh pounded yam were not significantly different (p > 0.05). However, fresh pounded yam (8.5–8.9) and reconstituted foam-mat dried flour (7.4–8.5) samples were significantly different (p > 0.05) from the cabinet-dried (6.9–7.9) and commercial samples (7.2–7.8).     

Effect of Processing Methods on Physical,Chemical, Rheological,and Sensory Properties of Okra (<Emphasis Type="Italic">Abelmoschus esculentus</Emphasis>)

Effects of freezing/thawing, sun drying, solar drying, and foam-mat drying on physical, chemical, rheological, and sensory attributes of okra were investigated. Average poured bulk and tapped bulk densities of sun-dried, solar-dried, and foam-mat-dried okra were 800 and 950, 715 and 765, 355 and 367 kg/m³, respectively. Minimum and maximum porosity of sun-dried, solar-dried, and foam-mat dried okra were 55.70% and 62.60%, 50.06% and 53.30%, 60.90% and 62.87%, respectively. Sun-dried and solar-dried okra showed higher L*, a*, and chroma values than frozen/thawed and foam-mat-dried okra. Within a temperature range of 80–40 °C, viscosity of fresh, frozen/thawed, foam-mat-dried, solar-dried, and sun-dried okra were 0.055–0.080, 0.055–0.075, 0.050–0.073, 0.005–0.065, and 0.005–0.022 Nsm⁻², respectively. Sensory evaluation showed no significant difference (p < 0.05) between fresh, frozen/thawed, and foam-mat dried okra in color, aroma, and overall acceptability. Sun-dried and solar-dried okra were significantly poorer (p < 0.05) in color, aroma, taste, and overall acceptability.     

Concentrations of cadmium and lead in different types of milk

 Concentrations of Pb and Cd were determined in samples of human, raw and pasteurized cow's and goat's milk and powdered infant formula. The following mean Cd concentrations (and ranges) were recorded: in human milk, 2.70 μg/l (0.6–11.3, n=55); in raw cow's milk, 4.88 μg/l (0.7–23.1, n=47); in pasteurized cow's milk, 4.30 μg/l (3.4–5.9, n=6); in goat's milk, 7.81 μg/l (1.0–18.4, n=38); and in powdered, infant formula, 3.81 μg/l (3.4–4.1, n=5). The concentrations (and ranges) of Pb were: in human milk, 8.34 μg/l (0.1–32.3, n=55); in raw cow's milk, 14.82 μg/l (1.3–39.1, n=28); in pasteurized cow's milk, 10.25 μg/l (6.9–19.6, n=6); in goat's milk, 11.86 μg/l (0.4–38.5, n=36); and in powdered, infant formula, 8.30 μg/l (5.1–10.6, n=5). Our data were within the normal ranges for each kind of milk. The Cd and Pb concentrations in goat's milk were significantly higher than the concentrations observed in the other milks, whereas human milk and powdered infant formula presented the lowest Cd and Pb concentrations. A considerable decrease in the concentration of Cd with the stage of lactation was observed. The concentrations of Cd and Pb in human, cow's and goat's milk also varied according to the time of year. The concentrations of Pb and Cd in the different milks did not present any risk to human health (infants or adults). Received: 26 May 1998     

Recovery of Native Potato Protein Comparing Expanded Bed Adsorption and Ultrafiltration

Obtaining native protein from potato fruit water (PFW) acceptable for food consumption was attempted by comparing expanded bed adsorption (EBA) and ultrafiltration (UF).The methods were assessed on their process performance and the product quality. Extractable tuber proteins were recovered from lab-prepared PFW either by adsorption to an EBA column using a mixed mode resin (0.31 L) or by batch concentration in an UF (10 kDa MWCO, 0.093 m²) unit and then freeze dried. The yields on protein and esterase activity were higher (p < 0.05 and p < 0.01; Mann–Whitney U-test) in UF (3.2 g l⁻¹ PFW and 3.17 kU l⁻¹ PFW) than in EBA (1.8 and 1.21). The performance difference was also reflected in process productivity for esterase activity which was fivefold better (p < 0.01) in UF (4.30 kU h⁻¹) than with EBA (0.84) due to the higher enzyme retention; protein productivities were the same. The content of solanidine glycoalkaloids was depleted to moderate levels but came out unaffected by the processing method: EBA 286 ppm, UF 213 ppm. The low levels of chlorogenic acid in all EBA preparations were negatively correlated to high brightness score (L* = 73.8%), a favorable attribute in food-quality proteins. Both methodologies produced native preparations of comparable protein content (75%). EBA processing, however, increased the fraction of the patatin protein which may offer advantages in food applications.