Development of a highly sensitive and specific monoclonal antibody-based enzyme-linked immunosorbent assay for determination of doxycycline in chicken muscle,liver and egg

A modified indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) method was developed using a highly sensitive and specific monoclonal antibody (McAb) to determine doxycycline (DC) residues in chicken tissues and egg. The McAb against DC was produced by hybridoma technique and a modified ic-ELISA was characterised in terms of sensitivity, specificity, precision and accuracy. At optimal experimental conditions, the standard curve was constructed at concentrations ranged from 0.01 to 100 ng/ml. The IC₅₀ value was 1.32 ± 0.18 ng/ml. The limit of detection was 0.14 ± 0.02 ng/g. The recoveries of DC from spiked chicken liver, muscle, and egg at levels of 50–600 ng/g were 84.6–85.5%, 88.2–89.1%, and 84.4–89.3%, respectively. The coefficient variations (CVs) were 5.1–9.3%, 3.7–11.3%, and 4.7–9.8%, respectively. Linear regression analysis showed good correlation, with r² values 0.9909 for chicken liver and 0.9916 for chicken muscle.     

Immunoassay based on monoclonal antibody for aflatoxin detection in poultry feed

An indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) based on an anti-aflatoxin B₁ monoclonal antibody was standardised and validated for aflatoxin screening in poultry feed samples and its performance was compared to high-performance liquid chromatography (HPLC). The ic-ELISA showed good linearity (r² = 0.994) and detection limits of 1.25 ng g⁻¹ for broiler feed and 1.41 ng g⁻¹ for laying hen feed. Mean aflatoxin recovery rates by ic-ELISA were 102% (laying hen feed) and 98% (broiler feed). Aflatoxins were detected in 88.2% of the 34 broiler feed samples by ic-ELISA and HPLC at means of 10.48 ng g⁻¹ and 8.41 ng g⁻¹, respectively, while 92% of laying hen feed samples (n = 36) showed aflatoxin contamination at means of 20.83 and 19.75 ng g⁻¹. The standardised ic-ELISA showed reliability and a high correlation with HPLC of 0.97 (broiler feed) and 0.98 (laying hen feed) indicating its potential for aflatoxin screening in poultry feed samples.     

Development of an indirect competitive immunoassay for parathion in vegetables

An indirect competitive immunoassay for the insecticide parathion has been optimized and characterized. This assay is based on a monoclonal antibody (2H₉) produced from an immunogen, a bovine thyroglobulin (BTG) conjugate wherein the reduced form of parathion was multiply bound to the carrier protein via diazo bonds. Assay was performed in the parathion-HSA coated (0.25 μg/ml) ELISA format in which antibody was diluted 1:2000. Several physicochemical factors (pH, ionic strength, BSA concentrations and organic solvent) that influence assay performance were studied and optimized. Finally, the assay was applied to the analysis of parathion in spiked vegetable samples. The sensitivity, estimated as the IC₅₀ value, was 360 ng/ml, with a practical working range between 47 and 6000 ng/ml, a limit of detection of 26 ng/ml, and inter-assay and intra-assay variations less than 10%. The average recovery of parathion added to potato, celery and Chinese cabbage were 173 ± 34%, 108 ± 15% and 98 ± 6%, respectively.     

Indirect competitive ELISA based on monoclonal antibody for the detection of 5-hydroxymethyl-2-furfural in milk,compared with HPLC

In this study, a method for rapid detection of 5-hydroxymethyl-2-furfural (HMF) was investigated. Monoclonal antibody (anti-HMF) was prepared and evaluated by an indirect competitive ELISA (ic-ELISA) format. The optimized standard curve was y = -0.2097 x + 1.0432 [where x is the logarithm (base 10) of the values of the HMF concentration and y is the absorbance of ic-ELISA results tested at 490 nm] and the linear detection range was 0.008 to 32.768 mg/L. The percentage of cross-reactivity of HMF with 5 major furfural derivatives was less than 2.92%. Finally, the established ic-ELISA format was used to test HMF in milk, and compared with the result obtained by HPLC, which produced an error of about 0.3%. Based on the data in this experiment, we concluded that the established ic-ELISA format was reliable with a high specificity.     

Antioxidative activity of Rosmarinus officinalis L. essential oil compared to its main components

This study was designed to examine the in vitro antioxidant activities of Rosmarinus officinalis L. essential oil compared to three of its main components (1,8-cineole, α-pinene, β-pinene). GC–MS analysis of the essential oil resulted in the identification of 19 compounds, representing 97.97% of the oil, the major constituents of the oil were described as 1,8-cineole (27.23%), α-pinene (19.43%), camphor (14.26%), camphene (11.52%) and β-pinene (6.71%). The oil and the components were subjected to screening for their possible antioxidant activity by means of 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and β-carotene bleaching test. In the DPPH test system, free radical-scavenging activity of R. officinalis L. essential oil, 1,8-cineole, α-pinene and β-pinene were determined to be 62.45% ± 3.42%, 42.7% ± 2.5%, 45.61% ± 4.23% and 46.21% ± 2.24% (v/v), respectively. In the β-carotene bleaching test system, we tested series concentration of samples to show the antioxidant activities of the oil and its main components, whereas the concentrations providing 50% inhibition (IC₅₀) values of R. officinalis L. essential oil, 1,8-cineole, α-pinene and β-pinene were 2.04% ± 0.42%, 4.05% ± 0.65%, 2.28% ± 0.23% and 2.56% ± 0.16% (v/v), respectively. In general, R. officinalis L. essential oil showed greater activity than its components in both systems, and the antioxidant activities of all the tested samples were mostly related to their concentrations. Antioxidant activities of the synthetic antioxidant, ascorbic acid and BHT, were also determined in parallel experiments as positive control.     

Effect of protein supply on hepatic synthesis of plasma and constitutive proteins in lactating dairy cows

The effects of metabolizable protein (MP) supply on the synthesis of plasma total proteins and albumin, as well as total hepatic protein synthesis, were determined in 6 multicatheterized lactating Holstein cows. Three TMR formulated to supply the same amount of energy but different amounts of MP, 1,922 (low), 2,264 (medium), and 2,517 g of MP/d (high), were fed every 2 h according to a double 3 × 3 Latin square design. For the low and high MP treatments, the cows were continuously infused with [²H₅]Phe (d5-Phe) into a jugular vein for 8 h (1.3 mmol/h) on d 21 of each period. Concentration and isotopic enrichment of d5-Phe were measured for free plasma Phe, plasma total proteins, and albumin on hourly samples collected between 3 and 8 h. Low MP decreased the plasma albumin concentration (32.3 vs. 33.7 ± 0.11 g/L) but the plasma total protein concentration was unchanged (74.1 vs. 75.6 ± 1.13 g/L). Incorporation of d5-Phe over time into both plasma total proteins and albumin was linear (R² > 0.98). Neither fractional nor absolute synthesis rates of plasma total proteins (6.8 vs. 6.5 ± 0.65%/d; 168 vs. 154 ± 19.9 g/d) or albumin (3.4 vs. 3.4 ± 0.10%/d; 36.3 vs. 36.5 ± 1.11 g/d) were affected by the MP supply. Net hepatic removal of Phe was lower with the low-MP diet (−12.3 vs. −20.2 ± 1.98 mmol/h). As a result, net hepatic Phe removal used for total export protein synthesis (17.9 vs. 11.1 ± 1.83%) and albumin synthesis (4.6 vs. 2.9 ± 0.54%) tended to be greater at low MP. These results suggest that hepatic synthesis of plasma proteins, including albumin, is maintained in lactating dairy cows even when the protein supply is reduced.     

Development of a sensitive monoclonal-based enzyme-linked immunosorbent assay for monitoring T-2 toxin in food and feed

The consumption of food or feed contaminated with high levels of T-2 toxin may cause adverse health effects in humans and other animals. In this study, to monitor T-2 toxin rapidly in food and feed, a sensitive and specific monoclonal antibody (mAb) against T-2 toxin was generated and a simple and rapid indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) developed. T-2 toxin was first converted to T-2-hemisuccinate (T-2HS) and T-2-hemiglutarate (T-2HG), which were then conjugated to bovine serum albumin (BSA) and ovalbumin (OVA) to prepare an immunogen and coating antigen, respectively. After the inoculation of female Balb/c mice and cell fusions, one cell line, 4D8, with the IgG1 isotype was obtained. The 4D8 antibody exhibited the ability specifically to recognise T-2 toxin with IC₅₀ 1.46 µg l^?1. Based on this 4D8 mAb, an optimised ic-ELISA protocol was developed using only methanol–water (7:3, v/v) in feed and cereal samples and ethyl acetate in muscle samples. The limits of detection of T-2 toxin in various sample matrices varied from 0.07 to 15.8 µg kg^?1; the recoveries ranged from 50.3% to 113.6%; and the CVs were less than 19.0%. These results suggest that the prepared mAb and the developed ic-ELISA method will be a useful tool for detecting T-2 toxin in foods and feeds.     

Antioxidant potential of solvent extracts of Kappaphycus alvarezii (Doty) Doty – An edible seaweed

Various solvent extracts of Kappaphycus alvarezii, an edible red seaweed (family Solieriaceae) were screened for total phenol content and antioxidant activity using 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferrous ion chelating activity, reducing power and antioxidant activity assays in a linoleic acid system with ferrothiocyanate reagent (FTC). The total phenol content of different extracts of K. alvarezii varied from 0.683 ± 0.040% to 2.05 ± 0.038%. The radical-scavenging activity of ethanol extract was, as IC₅₀ 3.03 mg ml⁻¹, whereas that of the water extract was IC₅₀ 4.76 mg ml⁻¹. Good chelating activity was recorded for methanol extract (IC₅₀ 3.08 mg ml⁻¹) wherein 67.0 ± 0.924% chelation was obtained using 5.0 mg ml⁻¹ of extract. The reducing power of the samples was in the following order: BHT > methanol > ethanol > ethyl acetate > water > hexane. But, in the linoleic acid system, the ethanol extract proved superior to the synthetic antioxidants butylated hydroxytoluene (BHT). Hence, these extracts could be considered as natural antioxidants and may be useful for curing diseases arising from oxidative deterioration.     

Determination of total arsenic in soft drinks by hydride generation atomic fluorescence spectrometry

A highly sensitive and simple method has been developed for the determination of total arsenic, by continuous hydride generation and atomic fluorescence spectrometry (HGAFS), in refreshing drink samples as colas, teas and fruit juices. Samples were mixed with concentrated HCl and KI to obtain final concentrations of 2 mol l⁻¹ and 1%, respectively. These solutions were aspirated and merged with a reducing NaBH₄ 3% (m/v) solution, with sample and NaBH₄ flow rates of 12.5 and 1.5 ml min⁻¹, respectively. The hydride generated in a 170 cm reaction coil was transported to the detector with an Ar flow of 400 ml min⁻¹. The recovery values of added concentrations, from 0.1 to 0.9 ng ml⁻¹, of arsenic in colas, teas and fruit juices were 94 ± 5, 101 ± 9 and 94 ± 6, respectively, achieving variation coefficients between 0.1% and 9%, confirming the accuracy of developed procedure. Detection limit, ranged from 0.01 to 0.03 ng ml⁻¹. On comparing the direct determination with a reference procedure made after dry ashing operation it can be noticed that the direct approach provides a simplification of the handling and time consuming, achieving statistically comparative results.     

Short communication: Aflatoxin M1 in dairy products sold in Şanlıurfa,Turkey

The aim of this study was to detect the presence of aflatoxin M₁ (AFM1) in samples of raw milk (n = 38), UHT milk (n = 12), white pickled cheese (n = 50), and yogurt (n = 50) collected from the ?anl?urfa city markets and locally produced dairy products by ELISA. The mean contamination rates were 56.74 ± 40.32, 43.1 ± 23.19, 103.2 ± 29.13, and 55.28 ± 12.68 ng/kg, respectively, for raw milk, UHT milk, white pickled cheese, and yogurt. According to the data, 21 (55%) raw milk, 3 (25%) UHT milk, 10 (20%) white pickled cheese, and 10 (20%) yogurt samples were contaminated with AFM1 over the acceptable levels (≥50 ng/kg), ranging from 0.82 to 130.89 ng/kg. None of the white pickled cheese samples contained AFM1 levels above the Turkish legal limit (250 ng/kg). Consequently, the AFM1 contamination levels determined in this study in white pickled cheese were not considered to pose a serious public health hazard. However, the AFM1 levels in raw and UHT milk and yogurt samples indicate an increased human health risk in Turkey related to high aflatoxin levels. Therefore, milk and dairy products have to be monitored by the Turkish public health authorities continuously to detect AFM1 contamination.     

Determination of Cd,Cu, and Zn in fish and mussel by AAS after ultrasound-assisted acid leaching extraction

An ultrasound-assisted solid–liquid extraction procedure by using diluted mixed acid solution was developed for determination of cadmium, copper and zinc in fish and mussel samples. The effects of several parameters such as nitric acid concentration, hydrochloric acid concentration, hydrogen peroxide concentration, leaching solution volume, and sonication time have been investigated. A 30-min sonication, 56 °C operating temperature and 6 mL of 1:1:1 HNO₃(4 M):HCl(4 M):H₂O₂(0.5 M) were used for 0.5 g of dried sample. Cadmium and copper were determined by graphite furnace atomic absorption spectrometry, and zinc was determined by flame atomic absorption spectrometry. The results obtained from the proposed procedure were evaluated by comparison with the results obtained by microwave-assisted digestion. Ratio (%) of metal amount obtained from leaching technique to amount obtained from digestion technique for cadmium, copper and zinc ranged from 92% to 114% for fish and from 88% to 103% for mussel samples. The MDL were 0.02, 0.13 and 0.63 mg kg⁻¹ for cadmium, copper and zinc, respectively. The accuracy of the developed method was investigated by analyzing a dogfish muscle certified reference material (DORM-2). Recoveries were obtained in the order of 80.9 ± 0.3 and 87.2 ± 0.6%.     

Development of a locally sustainable functional food based on mutandabota,a traditional food in southern Africa

A probiotic dairy product was developed on the basis of a traditional dish called mutandabota to enable resource-poor populations in southern Africa to benefit from a functional food. Mutandabota is widely consumed in rural southern Africa, making it an ideal food matrix to carry probiotics. First, a process to produce probiotic mutandabota was designed. Raw cow milk was boiled and subsequently cooled to ambient temperature (25°C). Next, dry pulp from the fruit of the baobab tree (Adansonia digitata L.) was added to the milk at a concentration of 4% (wt/vol). This mixture was inoculated with the probiotic Lactobacillus rhamnosus yoba and left to ferment for 24 h, while the growth of the bacterial culture was monitored. Final ingredients were then added to produce probiotic mutandabota that had 14% (wt/vol) baobab fruit pulp and 7% (wt/vol) sugar in cow milk. The pH of probiotic mutandabota was pH 3.5, which ensures that the product is microbiologically safe. The viable plate count of L. rhamnosus yoba increased from 5.8 ± 0.3 log cfu/mL at the point of inoculation to 8.8 ± 0.4 log cfu/mL at the moment of consumption, thereby meeting the criterion to have a viable count of the probiotic bacterium in excess of 6 log cfu/mL of a product. Baobab fruit pulp at 4% promoted growth of L. rhamnosus yoba with a maximal specific growth rate (μ_max) of 0.6 ± 0.2/h at 30°C. The developed technology, though specific for this particular product, has potential to be applied for the delivery of probiotics through a variety of indigenous foods in different regions of the world. Upon consumption, probiotic mutandabota is expected to improve the population's intestinal health, which is especially relevant for vulnerable target groups such as children and elderly people.     

The production of intrinsically labeled milk and meat protein is feasible and provides functional tools for human nutrition research

Administration of labeled, free amino acids does not allow direct assessment of in vivo dietary protein digestion and absorption kinetics. Consequently, dietary protein sources with labeled amino acids incorporated within their protein matrix are required. The aim of the present study was to produce intrinsically l-[1-¹³C]phenylalanine-labeled milk and meat protein that would permit in vivo assessment of postprandial protein digestion and absorption kinetics in humans. One lactating dairy cow was continuously infused with 420 μmol of l-[1-¹³C]phenylalanine/min for 96 h, with plasma and milk being collected before, during, and after isotope infusion. Twenty-four hours after infusion, the cow was slaughtered to produce intrinsically labeled meat. Levels of l-[1-¹³C]phenylalanine enrichment as high as 40 mole percent excess (MPE) in milk and 1.5 MPE in meat protein were achieved. In a subsequent human proof-of-principle experiment, 2 healthy young males (25 ± 1 yr; 66.2 ± 5.2 kg) each ingested 135 g of l-[1-¹³C]phenylalanine intrinsically labeled minced beef, after which plasma samples were collected at regular time intervals. Plasma l-[1-¹³C]phenylalanine enrichments increased during the first 90 min following beef ingestion, reaching peak plasma enrichment levels of 0.61 ± 0.04 MPE. Whole-body net protein balance, assessed by continuous infusion of l-[ring-²H₅]phenylalanine and l-[ring-²H₂]tyrosine, was higher in the postprandial period compared with basal values (6.4 ± 0.1 vs. −4.5 ± 0.1 μmol/kg per h). In conclusion, the production of intrinsically l-[1-¹³C]phenylalanine-labeled milk and meat protein is feasible and provides functional tools to investigate in vivo protein digestion and absorption kinetics in humans.     

Angiotensin I-converting enzyme inhibitory activity of low-molecular-weight peptides from Atlantic salmon (Salmo salar L.) skin

Collagen extracted from Atlantic salmon (Salmo salar L.) skin (which is normally discarded in the process of manufacture) was hydrolyzed with Alcalase and papain, and treated by multistage separation. The salmon skin collagen peptides (SSCP) obtained had high protein content (91.20 ± 1.03%) and low molecular weights, 90.79% of which were less than 1000 Da. SSCP was then separated by reversed-phase high performance liquid chromatography. Eleven major fractions were collected and their angiotensin I-converting enzyme (ACE) inhibitory activity was assayed. Fractions 5 and 7 displaying higher ACE inhibitory activity were subjected to mass spectrometer to identify the ACE inhibitory peptides. A total of eleven peptide sequences were identified, and two dipeptides, Ala-Pro and Val-Arg, were selected for further ACE inhibitory activity analysis. The ACE inhibitory activities of Ala-Pro (IC₅₀ = 0.060 ± 0.001 mg/ml) and Val-Arg (IC₅₀ = 0.332 ± 0.005 mg/ml) were found to be approximately 20- and 4-fold higher than that of SSCP (1.165 ± 0.087 mg/ml), respectively.     

Technical note: The use of a telemetric system to continuously monitor ruminal temperature and to predict ruminal pH in cattle

The objective of this study was to compare a telemetric monitoring system to an existing in situ methodology (conventional system) of monitoring ruminal temperature and to validate its use to detect changes in ruminal pH (RpH). Four nonlactating, ruminally cannulated Holstein dairy cows (760 ± 30 kg of body weight, mean ± standard deviation) housed in a tie-stall facility were used in the study. The experiment was conducted during the month of May and the recorded ambient temperature was 8.0 ± 2.0°C (mean ± SD). The cows were fed a diet consisting of chopped mixed hay (MH; 11.3% crude protein, 59.7% neutral detergent fiber, 17.3% nonfiber carbohydrate, 3.1% ether extract, and 11.3% ash; dry matter basis) during wk 1 and were gradually switched to a high-grain (HG) diet (11.6% crude protein, 30.2% neutral detergent fiber, 50.7% nonfiber carbohydrate, 3.0% ether extract, and 6.0% ash; dry matter basis) during wk 2. A conventional system that utilized an indwelling electrode was used to monitor RpH and ruminal temperature (RT_C) during d 6 and 7 of each week. The indwelling electrode was attached to a telemetric bolus and ruminal temperature (RT_T) was logged into a personal computer. The daily mean, minimum, and maximum RpH and duration (min/d) RpH <6.2 were 6.39 ± 0.04, 6.10 ± 0.05, 6.66 ± 0.03, and 107 ± 50 during MH feeding (wk 1) and 5.84 ± 0.03, 5.35 ± 0.05, 6.35 ± 0.03, and 1,257 ± 40 during HG feeding (wk 2), respectively, and were different across diets (week effect). Ruminal pH did not decrease below 5.6, 5.8, and 6.0 during MH feeding; mean duration of RpH <5.6, <5.8, and <6.0 during HG feeding was 279 ± 149, 611 ± 139, and 894 ± 101, respectively. Mean daily RT_C increased from 37.5?C ± 0.1 in wk 1 to 38.6°C ± 0.1 in wk 2; there was also an increase from wk 1 to wk 2 in minimum and maximum daily RT_C and durations (min/d) of RT_C >38.0, >38.2, >38.4, and >38.6°C. These increases were not detectable with the telemetric system. Ruminal temperature obtained by the conventional system was 0.68°C ± 0.005 lower than RT_T during MH feeding (wk 1), whereas RT_C was 0.04°C ± 0.004 higher than RT_T during HG feeding (wk 2). Daily minimum RpH was associated with maximum daily RT_C and RT_T during MH and HG feeding (R² = 0.88 and 0.43, respectively). There was a high association between low RpH and high ruminal temperature, with the highest associations being between duration (min/d) of RpH <6.0 and duration of RT_C >39.0°C (R² = 0.68) and RT_T >39.2°C (R² = 0.72). Unlike the telemetric system, the conventional system requires cow cannulation; therefore, the current study provided a noninvasive alternative for measuring ruminal temperature and the prediction of RpH. Additional studies are needed to develop an algorithm that accounts for diet type, seasonal variation in temperature, and core body temperature to predict subacute ruminal acidosis effectively on farm.     

Changes in physico-chemical, microbiological, textural and sensory attributes during ripening of dry-cured foal salchichón

The changes in the physico-chemical, microbiological, textural and sensory attributes of foal salchichón were followed during ripening. Foal salchichón samples were taken at 0 days (mix before stuffing), and after 7, 14, 21, 28, 35, 42 and 49 days of ripening. The final a_w was 0.82, whereas pH values stayed around their initial values. TBAR'S values increased significantly (P < 0.001) during processing, from 0.44 to 2.26 mg/kg of sausage. Ripening time also affected the lightness (L*), redness (a*) and yellowness (b*) (P < 0.001). Hardness, gumminess and chewiness increased (P < 0.001) from 0.96, 0.6 and 0.47 to 46.92 kg/cm², 21.34 kg/cm² and 15.14 kg, respectively during processing, whereas cohesiveness and springiness values decreased during ripening. Lactic acid bacteria increased slowly in number and a large increase of Micrococcaceae was noticed. Regarding sensorial characteristics, foal salchichón samples showed high values for intensity of flavour (7.22 ± 0.44), hardness (7.33 ± 0.71) and dryness (6.67 ± 0.71) and low scores for acid taste (1.67 ± 0.71) and saltiness (3.11 ± 0.6).     

The effect of calcium-naloxone treatment on blood calcium, beta-endorphin, and acetylcholine in milk fever

Milk fever is a postpartum syndrome of cows characterized by acute hypocalcemia, which reduces the release of acetylcholine (ACH), inducing flaccid paralysis and recumbency. Our aim was to evaluate the effect of calcium (Ca²⁺) combined with naloxone (Nx, an opioid antagonist; Ca²⁺-Nx) on plasma concentrations of ACH, ß-endorphin (ßE), and Ca²⁺ just before treatment (T0) and at 15, 30, and 90 min after treatment (T15, T30, and T90, respectively). Thirty cows were divided into 3 groups of 10 cows each. In group A1, cows affected by milk fever were treated (i.v.) with a combination of 0.2 mL/kg of body weight (BW) of Ca²⁺ borogluconate (20%) and 0.01 mg/kg of BW of Nx hydrochloride dihydrate. In group A2, cows affected by milk fever were treated (i.v.) with 2 mL/kg of BW of Ca²⁺ borogluconate (20%). In group C, healthy cows were treated (i.v.) with a combination of 0.2 mL/kg of BW of Ca²⁺ borogluconate (20%) and 0.01 mg/kg of BW of Nx hydrochloride dihydrate. Cows underwent treatments within 24 h of calving. Blood samples were collected at T0 and at T15, T30, and T90 for quantitative determination of ACH, ßE, and Ca²⁺. The cows in groups A1 and A2 recovered within a mean of 20 ± 10 min, although 4 cows in group A2 underwent a relapse. Blood Ca²⁺ concentrations in group C increased slightly at T30 and at T90 (T30: 8.8 ± 0.6 mg/dL; T90: 8.7 ± 0.6 mg/dL) after treatment, whereas the response in groups affected by milk fever was similar, even though Ca²⁺ concentrations showed a sharp increase (A1: 8.9 ± 0.8 mg/dL; A2: 6.0 ± 0.7 mg/dL), particularly at T15 in group A1. Concentrations of ßE showed a similar pattern in groups A1 and C, with an increase at T15 (A1: 8.2 ± 1.0 ng/mL; C: 2.7 ± 0.4 ng/mL) and a subsequent decrease until T90 (A1: 1.4 ± 0.3 ng/mL; C: 1.4 ± 0.4 ng/mL), whereas ßE remained constant throughout in group A2. Concentrations of ACH in group A1 decreased significantly between T0 and T15, T30, and T90 (T0: 7.2 ± 1.1 nmol/L; T15: 4.2 ± 1.2 nmol/L; T30: 2.9 ± 0.8 nmol/L; T90: 3.1 ± 0.3 nmol/L), whereas in group A2, it did not change. In group C, concentrations of ACH decreased at T15 and increased again at T30 (T15: 1.1 ± 0.3 nmol/L; T30: 3.2 ± 0.7 nmol/L). Our results suggest that administration of Ca²⁺-Nx, which restored the physiological Ca²⁺ concentrations, might have an effect on nicotinic receptors by restoring the normal neuromuscular transmission at the motor endplate.     

Antioxidant, antiacetylcholinesterase and antimicrobial activities of Cymbopogon schoenanthus L. Spreng (lemon grass) from Tunisia

Aqueous extract, proanthocyanidin rich extract, and organic extracts of Cymbopogon schoenanthus L. Spreng (lemon grass) shoots from three different locations in South Tunisia were screened for their antioxidant, acetylcholinesterase and antimicrobial activities. In addition to the evaluation of these activities, the contents of flavonoids and total phenolic compounds were determined.Antioxidant activity measured by DPPH assay showed that the proanthocyanidin extract exhibited higher antioxidant activity than the aqueous extract. Extract concentration providing 50% inhibition (IC₅₀) ranged from 16.4 ± 6.8 μg/mL to 26.4 ± 6.8 μg/mL. The antioxidant activity was also determined using the β-carotene/linoleic acid bleaching test. The best results (IC₅₀ = 0.11 ± 0.10 mg/mL) were obtained with the proanthocyanidin extract of the plants collected from the desert region (Dhibat).The greatest acetylcholinesterase inhibitory activity (IC₅₀ = 0.23 ± 0.04 mg/mL) was exhibited by the ethyl acetate and methanol extracts of the plants collected from the mountainous region. It seems that extracts obtained with more polar solvents gave better results.The proanthocyanidin extracts showed a good antimicrobial activity against Streptococcus sobrinus at low concentration (MIC = 4 mg/mL). Therefore, these extracts could be used to prevent carious lesions by inhibiting S. sobrinus growth.     

Short communication: Investigation of aflatoxin M1 levels in infant follow-on milks and infant formulas sold in the markets of Ankara,Turkey

Aflatoxins are fungal toxins known to be carcinogenic and are classified as food contaminants. This study was performed to investigate aflatoxin (AF) M₁ levels in baby foods sold in Ankara (Turkey) and to evaluate the obtained results according to the Turkish Food Codex (TFC). For this purpose, a total of 84 baby food samples (50 follow-on milks and 34 infant formulas) were obtained from different markets in Ankara and the presence of AFM₁ in the samples was analyzed by ELISA. In 32 (38.1%) of 84 infant food samples, the presence of AFM₁ was detected in concentrations ranging between 0.0055 and 0.0201 µg/kg. The mean level (±standard error) of AFM₁ was found to be 0.0089 ± 0.0006 µg/kg in positive infant follow-on milks. Aflatoxin M₁ was detected in only 1 infant formula sample (2.94%) at a concentration of 0.0061 µg/kg. The extrapolated levels of AFB₁ contamination in feedstuffs were calculated based on levels of AFM₁ in baby food samples. The data estimating AFB₁ contamination in dairy cattle feedstuff indicate that contamination may range from 0.3410 to 1.2580 µg/kg, with the mean level (±standard error) being 0.5499 ± 0.0385 µg/kg, which is lower than the level set by the TFC and European Union regulations (5 µg/kg). According to the obtained results, the levels of AFM₁ in analyzed samples were within the allowed limit (0.025 µg/kg) set in the TFC. Low levels of AFM₁ in infant follow-on milks and infant formula samples obtained during the study do not pose a health risk to infants.     

Properties of recovered solids from stick-water treated by centrifugation and pH shift

Processing of sardine fishmeal generates pollution and waste with potentially useful protein. Sardine stick-water (SW) from fishmeal operation was submitted to a complementary centrifugation step followed by pH adjustment (acidic + alkaline) to recover solids for their compositional, functional and nutritional properties evaluation. Insoluble fractions (from acidic treatment (IF₁) and alkaline treatment (IF₂)) had a chemical composition of 76 ± 4 and 16.9 ± 3.1% protein, 12 ± 6.2 and 2.9 ± 1.9% fat, 7.9 ± 2 and 75.4 ± 2.6% ash, respectively. IF₁ and IF₂ were good sources of Ca⁺⁺, Mg⁺⁺, P³⁻, K⁺ and essential amino acids. IF₂ was whiter than IF₁ but less colour stable over time. Solubility of proteins from IF₁ and IF₂ was higher than that of commercially used materials such as egg albumin and sodium caseinate. IF₁ chemical, nutritional and functional characteristics suggest its potential use as food/feed compositional ingredient.