Improving the quality of fried oils by using different filter aids

The present study aimed to improve the quality of fried soybean, sunflower, palm and cottonseed oils. Synthetic (Magnesol XL) and natural (diatomaceous earth and kaolin) filter aids were used at various levels (1, 2 and 4%) to adsorb the secondary oxidation products of the oil. The metal patterns (the cations Si, Mg, Ca, Fe, Na, K, Al, Cu, Mn, Zn and the anions CO₃^2?, HCO₃^?, Cl^?, NO₃^?, NO₂^?, SO₄^2?) of Magnesol XL, diatomaceous earth and kaolin were determined. Some physical and chemical properties (refractive index, viscosity, colour, foam height, acid value, peroxide value, thiobarbituric acid value, iodine value, and conjugated diene and polymer contents) of non‐fried, fried and fried–treated soybean, sunflower, palm and cottonseed oils were determined. The frying process was performed at 180 °C ± 5 °C for 12 h continuous heating. The fried oils were treated with the synthetic and natural filter aids at 105 °C for 15 min. The results indicate that Magnesol XL, diatomaceous earth and kaolin contained Si + Mg, Si + Ca and Si + Al, respectively, as the basic metals. Frying soybean, sunflower, palm and cottonseed oils led to significant increases in refractive index, colour, foam height, viscosity, acid value, peroxide value, TBA value, conjugated diene and polymer contents and decrease in iodine value. Treatment of fried oils with Magnesol XL, diatomaceous earth and kaolin at the 1, 2 and 4% levels greatly improved the quality of fried oils. These findings indicate the high efficiency of the filter aids used in the present study in adsorbing the products of oil degradation. Copyright © 2006 Society of Chemical Industry     

Biofortification of lettuce (Lactuca sativa L.) with iodine: the effect of iodine form and concentration in the nutrient solution on growth,development and iodine uptake of lettuce grown in water culture

BACKGROUND: Iodine is an essential trace element for humans. Two billion individuals have insufficient iodine intake. Biofortification of vegetables with iodine offers an excellent opportunity to increase iodine intake by humans. The main aim was to study the effect of iodine form and concentration in the nutrient solution on growth, development and iodine uptake of lettuce, grown in water culture. RESULTS: In both a winter and summer trial, dose rates of 0, 13, 39, 65, and 90 or 129 µg iodine L^?1, applied as iodate (IO₃^?) or iodide (I^?), did not affect plant biomass, produce quality or water uptake. Increases in iodine concentration significantly enhanced iodine content in the plant. Iodine contents in plant tissue were up to five times higher with I^? than with IO₃^?. Iodine was mainly distributed to the outer leaves. The highest iodide dose rates in both trials resulted in 653 and 764 µg iodine kg^?1 total leaf fresh weight. CONCLUSION: Biofortification of lettuce with iodine is easily applicable in a hydroponic growing system, both with I^? and IO₃^?. I^? was more effective than IO₃^?. Fifty grams of iodine‐biofortified lettuce would provide, respectively, 22% and 25% of the recommended daily allowance of iodine for adolescents and adults. Copyright © 2010 Society of Chemical Industry     

Anwendung elektrischer Hochspannungsimpulse als Vorbehandlungsverfahren zur Beeinflussung der Trocknungscharakteristika und Rehydratationseigenschaften von Kartoffelwürfeln

High intensity electric field pulses as pretreatment for affecting dehydration characteristics and rehydration properties of potato cubes. High intensity electric field pulse (HELP) treatment was evaluated as pretreatment to possibly affect dehydration and rehydration characteristics of potato cubes (1 × 1 × 1 cm). Effects of electric field strength E = 0.35-3.0 kV · cm^?1 and number of pulses n = 1-70 on the degree of permeabilization of potato cells was evaluated using a centrifugal method. Optimization of E and n regarding maximum permeabilization of cells was performed. Energy requirements were found to be low (6.4-16.2 kJ · kg^?1) resulting in an increase in temperature in the treated product of _ΔT = 1.8-4.5°C. The HELP treatment enabled a maximum degree of permeabilization and resulted in a cell liquid release from potato cubes after centrifugation (700 × g) to up to 27-29% (untreated control 0%) as related to total water content. Treatment with optimum parameters (E = 0.9-2.0 kV · cm^?1, n = 15-30) resulted in improved mass transfer within the product and drying time during fluidized bed drying (T_tr = 55°C, 70°C, air velocity 2 m · s^?1) of potato cubes could be reduced to up to 20-25%. Rehydration properties and quality characteristics of the products after cooking were not affected by the high intensity electric field pulse pretreatment.     

Monitoring of Zn(II), Cd(II), Pb(II) and Cu(II) During Refining of Some Vegetable Oils Using Differential Pulse Anodic Stripping Voltammetry

In this study, a novel approach has been developed using differential pulse anodic stripping voltammetry (DPASV) for the simultaneous determination of Zn(II), Cd(II), Pb(II) and Cu(II) in edible oils at hanging mercury drop electrode. The microwave digestion of oil samples was carried out with concentrated HNO₃ and H₂O₂. KNO₃ was used as a supporting electrolyte. The experimental conditions optimized such as deposition time, stirring rate and size of mercury drop were 300 s, 600 rpm and 10 mm², respectively. The method was applied to quantify Zn(II), Cd(II), Pb(II) and Cu(II) in crude and refined hazelnut, corn, sunflower and olive oils. During refining of different vegetable oils, the removal efficiencies of Zn(II), Cd(II), Pb(II) and Cu(II) were calculated as 98.20–99.91, 98.50–99.90, 95.26–99.76 and 95.93–99.92 %, respectively. The limits of detection for Zn(II), Cd(II), Pb(II) and Cu(II) were 2.1?×?10^?8, 8.7?×?10^?10, 7.1?×?10^?9 and 3.4?×?10^?9 and the limits of quantification were 6.8?×?10^?8, 2.9?×?10^?9, 2.3?×?10^?8 and 1.1?×?10^?8 M with linear regression coefficients (R ²) of 0.9930, 0.9928, 0.9893 and 0.9931, respectively. It was observed that the above metals in crude and refined vegetable oils could be determined simultaneously by the DPASV method.     

Structural changes in squid (Loligo japonica) collagen after modification by formaldehyde

BACKGROUND: Formaldehyde (FA) has been suggested to cause changes in texture and functional properties in some marine species. It was therefore hypothesised that FA may affect collagen, a fundamental constituent of the extracellular matrix in squid. RESULTS: Two types of collagen, I and V, were isolated by pepsin digestion and differential salt precipitation. Type V collagen contained higher proportions of isoleucine, leucine, and lysine and lower proportions of alanine and hydroxyproline. The effects of FA on pepsin‐solubilised squid collagen were examined by differential scanning calorimetry and Raman spectroscopy. The squid collagen showed a transition temperature (T_m1) of 37.2 ± 0.2 °C, which was significantly reduced in the presence of 2 and 10 mmol L^?1 FA. In the presence of 1, 2 and 10 mmol L^?1 FA an additional peak (T_m2) was also observed at 77.7 ± 0.1, 78.4 ± 0.1 and 62.7 ± 0.2 °C respectively, suggesting FA–collagen interactions. Treatment with 2 mmol L^?1 FA increased the I₉₄₀/I₁₀₀₅ ratio from 1.09 to 1.66 and shifted the 990 and 1245 cm^?1 bands. The tyrosine doublet ratio (I₈₅₀/I₈₃₀) was also increased about threefold, suggesting that α helix, β sheet type and random coil structures were changed by FA. CONCLUSION: The secondary structure of squid collagen can be affected by FA through hydrophobic interactions. Copyright © 2008 Society of Chemical Industry     

PARTIAL CHARACTERIZATION OF TRYPSIN-CHYMOTRYPSIN INHIBITORS FROM BEAN (PHASEOLUS VULGARIS L., VAR. ROSINHA G2): CHEMICAL AND PHYSICAL PROPERTIES

The three trypsin inhibitors A, B and C previously isolated from Brazilian pink bean (Phaseolus vulgaris L. var. Rosinha G2) had molecular weights of 18,200 to 18,500 by sodium dodecyl sulfate polyacrylamide gel electrophoresis, 20,000 by gel filtration on Sephadex G-100 and 20,400 by sucrose density gradient ultracentrifugation with a Stokes molecular radius of 20 Å, a frictional coefficient of 1.14, a diffusion coefficient of 10.7 × 10^?7 cm²s^?1, a partial specific volume of 0.69 cm³g^?1 and a molar absorptivity of 5.5 × 10³ M^?1 cm^?1 at 280 nm. All three inhibitors bound two moles of trypsin and one mole of chymotrypsin. The K_i values for trypsin were: A, 8.5 × 10^?10 M; B, 1.8 × 10^?10 M and C, 6.8 × 10^?10 M while for chymotrypsin they were: A, 4.4 × 10^?7 M; B, 2.8 × 10^?8 M and C, 3.0 × 10^?8 M. Reductive methylation caused loss of inhibitor activity of all three inhibitors against trypsin without significantly affecting inhibitor activity against chymotrypsin (with exception of inhibitor B), indicating that the inhibitors have lysine in binding site for trypsin. Partial reduction of the disulfide bonds caused loss of inhibitor activity against both trypsin and chymotrypsin with some regain of inhibitor activity following dialysis. Cyanogen bromide cleaved all three inhibitors into two fragments with significant retention of inhibitor activity. Cyanogen bromide-treated inhibitor B had nearly twice the original inhibitor activity against trypsin with no loss of inhibitor activity against chymotrypsin.     

Quality of Malaysian cocoa butter during storage

Malaysian pure prime pressed and deodorised cocoa butters were obtained from local cocoa grinders and analysed for quality deterioration. Approximately 5 kg of each sample was packed in corrugated paper boxes lined with low‐density polyethylene plastic material of thickness 73.2 µm. The water vapour transmission rate and gas transmission rate (for oxygen) of the plastic material were 3.21 g m^?2 day^?1 (37.8 °C, 90 ± 2% RH) and 71.57 cm³ m^?2 day^?1 (23.0 °C, 0% RH) respectively. The butters were stored at 15 ± 4 °C and 70 ± 4% RH for up to 24 months. Samples were taken every 2 months and analysed for free fatty acid content, saponification value, iodine value, refractive index and peroxide value. The findings indicated that the free fatty acid content, iodine value and peroxide value of both types of cocoa butter increased with storage duration. The other parameters showed no significant changes. However, the free fatty acid content and peroxide value after 24 months of storage were still below the limits specified in Malaysia. Therefore we conclude that both types of Malaysian cocoa butter are still in good condition after 24 months of storage, with minimal quality deterioration. Copyright © 2004 Society of Chemical Industry     

Kinetics of Thermal Inactivation of Peroxidase and Color Degradation of African Cowpea (Vigna unguiculata) Leaves

Cowpea leaves form an important part of the diet for many Kenyans, and they are normally consumed after a lengthy cooking process leading to the inactivation of peroxidase (POD) that could be used as an indicator for the potential shelf life of the vegetables. However, color degradation can simultaneously occur, leading to poor consumer acceptance of the product. The kinetics of POD in situ thermal (for thermal treatments in the range of 75 to 100 °C/120 min) inactivation showed a biphasic first‐order model, with Arrhenius temperature dependence of the rate constant. The kinetic parameters using a reference temperature (T_ref) of 80 °C were determined for both the heat‐labile phase (k_ref = 11.52 ± 0.95 × 10^?2 min^?1 and E_a of 109.67 ± 6.20 kJ/mol) and the heat‐stable isoenzyme fraction (k_ref = 0.29 ± 0.07 × 10^?2 min^?1 and E_a of 256.93 ± 15.27 kJ/mol). Color degradation (L*, a*, and b* value) during thermal treatment was investigated, in particular as the “a*” value (the value of green color). Thermal degradation (thermal treatments between 55 and 80 °C per 90 min) of the green color of the leaves followed a fractional conversion model and the temperature dependence of the inactivation rate constant can be described using the Arrhenius law. The kinetic parameters using a reference temperature (T_refC = 70 °C) were determined as k_refC = 13.53 ± 0.01 × 10^?2 min^?1 and E_aC = 88.78 ± 3.21 kJ/mol. The results indicate that severe inactivation of POD (as an indicator for improved shelf life of the cooked vegetables) is accompanied by severe color degradation and that conventional cooking methods (typically 10 min/100 °C) lead to a high residual POD activity suggesting a limited shelf life of the cooked vegetables.     

Resonanz-Raman-Spektroskopie an Amylose-Iodkomplexen

Resonance Raman Spectroscopy of Amylose-Iodine Complexes. In order to investigate the existence of a preferred sequence length of the polyiodine chain or a change of the bound species depending on the DP of amyloses, resonance Raman measurements have been carried out with iodine complexes of synthetic amyloses (DP 20–200) and of pure maltooligomers (DP 3–18). In the range of DP 20–200 identical Raman spectra have been obtained with signals at 162, 112, 52 and 24 cm⁻¹. The main signal of the amylose-iodine complex at 162 cm⁻¹, which is resonance enhanced near the long wavelength absorption maximum, is still present in the Raman spectrum of maltooctaose. It is no more observed with linear maltohexaose, but clearly seen with α-cyclodextrin. Raman spectra give no evidence for any change of the bound iodine species depending on the length of the polyiodine chain. Raman spectra were widely unaffected by the I₂/KI ratio of the complexing solution. The results can easier be explained by a fully resonating polyiodine chain as earlier proposed by Cramer [1,2] (electron gas model) than by a polyiodine chain composed of discrete iodine species with regular distances between the subunits.     

Sorbic Acid and Potassium Sorbate Permeability of an Edible Methylcellulose-Palmitic Acid Film: Water Activity and pH Effects

The apparent permeability constants for potassium sorbate and sorbic acid through an edible film composed of methylcellulose and palmitic acid (weight ratio 3:1) were evaluated as a function of water activity (a_w) and pH. For films with thickness 55–66 μm, potassium sorbate permeability increased from 2.3 × 10^?10 to 2.0 × 10^?8 (mg/sec cm²)(cm)/(mg/mL) as a_w increased from 0.65 to 0.80. Films were not stable at a_w levels above 0.80. Permeability of the film to sorbic acid at a_w 0.8 decreased from 3.3 × 10^?8 to 9.1 × 10^?10 (mg/sec cm²)(cm)/ (mg/mL) as pH increased from 3 to 7. At pH 3 the undissociated acid was 97.5% and at pH 7 it was 0.4%.     

Influence of seed roasting process on the changes in composition and quality of sesame (Sesame indicum) oil

The composition and quality changes of sesame oils prepared at different roasting temperatures (180–260°C) from sesame seed were evaluated and compared with an unroasted oil sample. There were no apparent differences in characteristics, such as acid value, iodine value, saponification value and refractive index, of sesame oils prepared at a roasting temperature between 180 and 220°C. The colour units and total polar content of oils increased in relation to an increase in roasting temperature. The phospholipid content was reduced from 690 mg kg^?1 in unroasted oil to 0 mg kg^?1 in the oil prepared using a 260°C roasting temperature. The fatty acid content of the oil was reduced markedly, especially in oleic and linoleic acids, when the roasting temperature was over 220°C. The amounts of chlorophyll and sesamolin decreased with increasing roasting temperature. However, the highest level of sesamol and γ-tocopherol was found in oils prepared with a 200–220°C roasting temperature. The sesame oil prepared at a 200°C roasting temperature had the best flavour score when compared with the other samples.     

Comparison of fruit characteristics,oil properties and fatty acid composition of local Syrian Kaissy cv olive (<Emphasis Type="Italic">Olea europaea</Emphasis>)

Characterization of Syrian (Kaissy cultivar) olive fruits and evaluation of physic-chemical properties of oils were carried out during 3 years of production. The mean values of data for both measured and calculated variables of fruits were: grain length (21.89 mm), grain width (17.92 mm), length/width (1.22), weight of grain (3.79 g), weight of pulp (flesh) (3.19 g), weight of pit (0.60 g), pulp/pit ratio (5.35), crude oil (17.13%), water content (moisture) (51.34%). The 3 year average values of chemical properties of Syrian Kaissy cultivar olive oils (SKOO) including acid value, peroxide vale, Thiobarbituric acid value, iodine value(IV), saponification value, and phenolic content were 0.58%, 4.33 mEq O₂ kg^??1, 0.028 mg MDA kg^??1 oil, 90.77 g I₂, 100 g^??1, 194.91 mg KOH g^??1, and 218.08 g gallic acid kg^??1, respectively. Pefractive index (RI), and viscosity were 1.4666 nD at 25?°C and 139.56 mPa.s, respectively. However, the 2 years average values of Hunter’s color parameters of SKOO were; the lightness (L*= 66.91), redness (a* = 18.80), yellowness (b* = 29.08) and the color differences (?E?=?65.49). FA analysis of the SKOO used showed a high content of monounsaturated fatty acids (oleic acid 70.82% and palmitic acid 1.01%) and low polyunsaturated fatty acids (Linoleic acid 10.72% and Linolenic 0.82%) and saturated fatty acids (Palmitic 14.10% and stearic 2.57%). Results for 3 years production of Syrian Kaissy cultivar olive fruit and oil are discussed in detail.     

Absorption of lodine into Starch Granules in Aqueous Suspension

The rate of iodine absorption by granular starch suspended in KI solution is examined. The rate controlling step is found to be the intraparticle diffusion of iodine. The process agrees well with a core-shrinking model. The apparent diffusivity of iodine in granular starch is determined to be (6.8 ± 0.5) × 10⁻⁸ cm²/sec at 25°C.     

Patulin Adsorption Kinetics on Activated Carbon, Activation Energy and Heat of Adsorption

The kinetics of adsorption of patulin on activated carbon were studied at different initial patulin concentrations (100–400 ppb) for the temperature range 20–80°C. Apparent adsorption rate constants (k_aapp) were changed from 1.07 × 10^?3 to 1.86 × 10^?3 g^?1 min^?1 while the temperature increased from 20 to 80°C. For equilibrium adsorption curves; the Langmuir model was attempted and model parameters (K and Q°) were obtained for different temperatures. Energy of activation and heat of adsorption were determined in a batch adsorption system (E_a= 2.02 kcal/mol and ΔH = 2.24 kcal/mol). The adsorption occurred endothermically and by physical mechanisms.     

Relative Oxidative Stability of Diacylglycerol and Triacylglycerol Oils

To compare the oxidative stability between diacylglycerol (DAG) oil and conventional triacylglycerol (TAG) oil (that is, soybean oil), the prepared stripped diacylglycerol oil (SDO) and soybean oil (SSBO) were stored at 60 °C in the dark for 144 h. During storage peroxide values (POVs), contents of aldehydes, unsaturated fatty acids were measured to evaluate the oxidative stabilities of the 2 oils. The results showed the content of C18:2, C18:3, and total unsaturated fatty acid decreased faster in DAG oil than in soybean oil, whereas the decreased rate of C18:1 was similar in 2 oils. Also, both rate constants (K₁ and K₂) obtained from POV (K₁) and total aldehydes (K₂) indicated that DAG oil (K₁ = 3.22 mmol/mol FA h^?1, K₂ = 0.023 h^?1) was oxidized more rapidly than soybean oil (K₁ = 2.56 mmol/mol FA h^?1, K₂ = 0.021 h^?1), which was mainly due to the difference of acylglycerol composition of the 2 oils along with higher C18:3 (9.6%) in SDO than SSBO (5.7%). It is concluded that DAG was more easily oxidized than soybean oil at 60 °C in the dark for 144 h.     

Temperature Dependence of Effective Diffusion Coefficient for Total Solids During Washing of Cheese Curd

The temperature dependence of the effective diffusion coefficient of total solids from small curd cottage cheese was estimated by fitting batch washing data at several temperatures (25°C, 35°C, 50°C, and 58°C) to a previously developed mass transfer model. The model was based on spherical geometry of curd particles. The correlation for diffusivity was found to be D_effective= (0.0658T + 1.72) × 10^?6, where D_effective is in cm²/sec and T is in °C.     

Evaluation of shortenings based on various palm oil products

Several formulations based on blends of hydrogenated palm oil (MP 41·5°C) and palm stearin (IV 44) with other liquid oils, on direct blends of palm stearin with other liquid oils, and on 100% inter-esterified palm olein, were used as feedstocks in shortening production. The shortenings were stored at 20°C over a period of one month. Physicochemical characteristics, creaming properties and baking performance of the shortenings were evaluated and compared with the best shortening on the market. Slip melting point of the shortenings ranged from 41·5 to 46·4°C. Palm-cottonseed oil shortenings had higher solid fat contents at all temperatures than palm-soya bean or palm-low erucic acid rapeseed oil shortenings. The shortenings were rich in C₅₀, C₅₂and C₅₄ glycerides. Creaming power after 12 min of beating ranged from 1·55 to 1·77 cm³ g^?1. Palm stearin-cottonseed (3:2) oil shortening showed the best creaming performance. The specific volume of cakes ranged, for the experimental shortening, from 90% to 101% from the control, with low erucic acid-palm blends showing the best performance. In applications for both aerated cream and cakes, inter-esterified palm olein was excellent.     

Migration of α-tocopherol from LDPE films to corn oil and its effect on the oxidative stability

The migration of α-tocopherol (α-T) from low density polyethylene (LDPE) films, added with 20 (film A) and 40 mg g^?1 (film B) to corn oil for 12 weeks at 5, 20 and 30 °C was determined. A LDPE film added with no α-T was used as control (film C). Diffusion coefficient (D) values for the film A system were 1.4 × 10^?11, 7.1 × 10^?11 and 30.3 × 10^?11 cm² s^?1 at 5, 20 and 30 °C, respectively. Meanwhile, D values for the film B system were 1.3 × 10^?11, 9.6 × 10^?11 and 51.1 × 10^?11 cm² s^?1 at the same temperatures. The activation energy (E_a) for the diffusion of α-T was 126.5 (film A) and 105.9 kJ mol^?1 (film B). The effect of the migration of α-T on the oxidative stability of corn oil was evaluated by monitoring hexanal content by solid phase micro-extraction (SPME) and gas chromatography. The hexanal content in the oil showed that both films added with α-T resulted suitable to maintain the oxidative stability of the oil for about 16 weeks at 30 °C, compared to 12 weeks for the oil in contact with the film C.     

Diffusion of Acetic and Propionic Acids from Chitosan-based Antimicrobial Packaging Films

The diffusion of acetic or propionic acids from thin (44 to 54 μm) chitosan‐based antimicrobial packaging films in which they were incorporated was measured after immersion of the films in water, and the effects of pH (5.7, 6.4, or 7.0) and temperature (4 °C, 10 °C, or 24 °C) on diffusion were investigated. The kinetics of acetic‐ and propionic‐acid release deviated from the Fickian model of diffusion. Diffusion was found to be unaffected by pH in the range of values tested, but a decrease in temperature from 24 °C to 4 °C resulted in a reduction of diffusion coefficients from 2.59 × 10^?12 m².s^?1 to 1.19 × 10^?12 m².s^?1 for acetic acid and from 1.87 × 10^?12 m².s^?1 to 0.91 × 10^?12 m².s^?1 for propionic acid. The effect of temperature on diffusion was well (r² > 0.9785) described by an Arrhenius‐type model with activation energies of 27.19 J.mole^?1 (acetic) and 24.27 J.mole^?1 (propionic). Incorporation of lauric acid or essential oils (cinnamaldehyde or eugenol) into the chitosan film at the time of preparation produced a subsequent reduction in the diffusion of acetic or propionic acid, and maximum effects were obtained with lauric acid and cinnamaldehyde incorporated to final concentrations of 1.0% and 0.5% (w/w), respectively.     

SERS Detection of Insecticide Amitraz Residue in Milk Based on Au@Ag Core-Shell Nanoparticles

A simple, rapid, and environmentally friendly surface-enhanced Raman scattering (SERS) method was developed for the determination of trace amitraz in milk with the use of silver-coated gold nanoparticles (Au@Ag NPs) as enhancing reagent. The normal Raman and SERS spectra of amitraz were analyzed, and the peaks were assigned by density functional theory. The morphology of Au@Ag NPs was characterized and confirmed by transmission electron microscopy, scanning electron microscopy, and ultraviolet-visible spectroscopy. The SERS effects of Au@Ag NPs were investigated, including the types of solvents for dissolving amitraz, the volume ratio of the Au@Ag NPs and amitraz, and the concentration of aggregating agent (NaCl) for aggregate Au@Ag NPs. Results show that ethanol exerts the least interference on the SERS spectrum of amitraz and is more environmentally sound than methanol. The strongest SERS signal appeared when the volume ratio of Au@Ag NPs and amitraz was 2:1. Moreover, the strongest SERS signals appeared when the concentration of NaCl was 0.025 mol L^?1 because of appropriate aggregation. Under the optimum conditions, the concentration of amitraz presents a good linear relationship with Raman intensity (723 cm^?1) with a linear range of 9.77 × 10^?4~2.93 × 10^?2 g L^?1. The detected recoveries of amitraz in milk were between 81.7 and 100.5% with a relative standard deviation (RSD) of 2.61~5.51%.