Kale Samples Research Articles

Combined Treatment on the Inactivation of Naturally Existing Bacteria and Escherichia coli O157:H7 Inoculated on Fresh-Cut Kale.

An aqueous chlorine dioxide (ClO₂) treatment combined with highly activated calcium oxide (CaO) and mild heat was tested for inactivating naturally existing bacteria and Escherichia coli O157:H7 inoculated on fresh-cut kale. Kale samples were treated with different concentrations of ClO₂ (10, 30, and 50 ppm), CaO (0.01%, 0.05%, 0.1%, and 0.2%), and mild heat (25°C, 45°C, 55°C, and 65°C) as well with combinations of 30 or 50 ppm ClO₂ and 0.2% CaO at 55°C for 3 min. An increasing concentration of ClO₂ and CaO significantly reduced the microbialpopulation compared with the control. In addition, mild heating at 55°C elicited greater microbial reduction than the other temperatures. A combined treatment of 50 ppm ClO₂ and 0.2% CaO at 55°C reduced the population of naturally existing bacteria on kale by 3.10 logcolony forming units (CFU)/g, and the counts of E. coli O157:H7 were below the detection limit (1 log CFU/g). In addition, no significant differences in the Hunter color values were evident in any treatment during storage. Therefore, a combined treatment of ClO₂ and active CaO at 55°C can be an effective sanitizing method to improve the microbiological safety of fresh-cut kale without affecting its quality.

Antimicrobial Activity of Marjoram (Origanum Majorana) Essential Oil Against the Multidrug‐Resistant Salmonella Enterica Serovar Schwarzengrund Inoculated in Vegetables from Organic Farming

AbstractAntimicrobial efficacy of the marjoram essential oil (MEO) on organic vegetables inoculated with 4 log/cfu Salmonella enterica serovar Schwarzengrund was evaluated. Previously inoculated samples of smooth lettuce (Lactuva sativa), kale (Brassica oleracea) and arugula (Eruca sativa) were immersed, separately, in three MEO solutions (0.1, 0.3 and 0.5%) for 1 and 2 min. Control groups with sterile phosphate‐buffered saline and sodium hypochlorite (250 ppm) solution were also used. The enumeration of Salmonella was performed for 3 consecutive days, and the essential oil yielded an average reduction in microbial load, ranging from 2.12–3.31 log/cfu, in all samples, against 1.86 − 2.81 log/cfu obtained by the traditional disinfection method with hypochlorite solution. In lettuce samples, the 0.5% MEO concentration showed similar efficacy to the hypochlorite control. The same concentration of essential oil tested in kale and arugula showed significant antimicrobial activity when compared to the same control. Sensory and affective tests showed good acceptability of the MEO flavor on lettuce leaves. According to this experimental model, this oil has promising antimicrobial activity against Salmonella enterica serovar Schwarzengrund and may be used to reduce or replace sodium hypochlorite during the disinfection process of vegetables.Practical ApplicationsThe marjoram essential oil at 0.5% concentration showed potential application in the disinfection process of vegetables for human consumption. Its disinfection capacity against a high concentration of multidrug‐resistant Salmonella enterica serovar Schwarzengrund was similar or even better than the sodium hypochlorite solution commonly used to remove or reduce the microbial load of fresh vegetables or similar foods.

Food safety in Thailand 2: Pesticide residues found in Chinese kale (Brassica oleracea), a commonly consumed vegetable in Asian countries

There is increasing public concern over human health risks associated with extensive use of pesticides in agriculture. Regulation of pesticide maximum residue limits (MRLs) in food commodities is established in many developed countries. For Thailand, this regulation exists in law but is not fully enforced. Therefore, pesticide residues in vegetables and fruits have not been well monitored. This study investigated the pesticide residues in Chinese kale, a commonly eaten vegetable among Asians. The Chinese kale samples (N=117) were purchased from markets in Nakhon Pathom Province, Thailand, and analyzed for the content of 28 pesticides. Analysis was performed by the multiresidual extraction followed by GC–MS/MS. Of pesticides investigated, 12 pesticides were detected in 85% of the Chinese kale samples. Although carbaryl, deltamethrin, diazinon, fenvalerate and malathion were found in some samples, their levels were lower than their MRLs. However, in 34 samples tested, either carbofuran, chlorpyrifos, chlorothalonil, cypermethrin, dimethoate, metalaxyl or profenofos was detected exceeding their MRLs. This represents a 29% rate of pesticide detection above the MRL; a rate much higher than in developed countries. Washing vegetables under running water significantly reduced (p<0.05) profenofos residues by 55%. The running water method did not significantly decrease cypermethrin residues in the samples but washing with vinegar did. Our research suggests that routine monitoring of pesticide residues is necessary to reduce the public health risks associated with eating contaminated vegetables. Washing vegetables before consumption is advisable as this helps to reduce the level of pesticide residues in our daily intake.

Innovative Pesticide Kit Model for Vegetable Farm Safety Surveillance Program

To develop 4-groups innovative pesticide test kit and vegetable farm safety surveillance program, the quasai study was performed in intervention klongtabak and control ta-ngoy village groups, Nakhonratchasima province. 62 Chinese kale samples were screened for pesticide residues using innovative test kit and confirmed by GLC/HPLC. Percent acetyl cholinesterase inhibition was measured in vegetable samples, containing anti-cholinesterase pesticide residues, using spectrophotometer. Pre-intervention analysis, two detected chlorpyrifos (>MRL) in control group, two detected cypermethrin (<MRL) and one detected <MRLs methomyl, carbofuran and carbofuran-3-OH in study group. No pesticides were detected in both groups at post-intervention. Self-test was trained to agriculturists, 92% accuracy competence results was acceptable at post-laboratory kit test training. Small farm land pesticide safety manual was used to educate agriculturists and %enzyme inhibition measurement at post-intervention period, compared with pre-intervention period was decreased 51.9% at p-value <0.011, reveal that intervention program affect reduction of pesticide inhibition at 0.05% significance level.

Thermal-induced changes of kale’s antioxidant activity analyzed by HPLC–UV/Vis-online-TEAC detection

Generally, boiling of vegetables is assumed leading to lower nutritional values because of leaching effects and activity loss of bioactive compounds. Kale (Brassica oleracea var. sabellica) reveals a great diversity of flavonoids, which have been shown to be good antioxidants. As Brassica vegetables are mainly consumed cooked, the influence of boiling on kale’s flavonoids and their antioxidant activity was investigated. Therefore, three kale cultivars were cooked at 100°C for 2 and 4h prior to analysis. The total phenolic content (TPC) and the total antioxidant activity (TEAC assay and EPR spectrometry) of each cultivar were determined and revealed no change, independent of cooking time, although kale samples visually altered. Using the HPLC–UV/Vis-online-TEAC approach, distinct changes in composition and antioxidant activity of the flavonoids were detectable. Thus, it was observable, that the antioxidant activities of the reaction products compensated the “loss” of the antioxidant activity of the original compounds of the uncooked material.

Sensory and microbiological qualities of romaine lettuce and kale affected by a combined treatment of aqueous chlorine dioxide and ultraviolet-C

The effects of a combined treatment of aqueous chlorine dioxide (ClO2) and ultraviolet-C (UV-C) on the sensory and microbiological qualities of Romaine lettuce and kale were examined. Samples of Romaine lettuce and kale were artificially inoculated with Escherichia coli O157:H7 and Salmonella enterica serotype Typhimurium. The inoculated Romaine lettuce and kale, as well as fresh samples, were treated with 50 L L−1 aqueous ClO2, 10 kJ m−2 UV-C, and a combination of aqueous ClO2 and UV-C, and stored at 4 for 7 days. The combined treatment of aqueous ClO2 and UV-C reduced the initial populations of total aerobic bacteria in the Romaine lettuce and kale by 2.07 and 2.49 log CFU/g, compared to 6.36 and 6.07 log CFU/g for the control, respectively. The combined treatment also reduced the populations of yeast and mold in the samples by 1.85 and 4.25 log CFU/g, respectively. In particular, E. coli O157:H7 and S. Typhimurium inoculated in the Romaine lettuce and kale were eliminated by the combined treatment. The Hunter ‘L’, ‘a’, and ‘b’ values of Romaine lettuce and kale were not significantly different among the treatments. Sensory evaluation results indicated that the combined treatment provided better scores than did the control. Our results suggest that the combined treatment of 50 L L−1 aqueous ClO2 with 10 kJ m−2 UV-C can be useful for maintaining the microbial safety and sensory qualities of Romaine lettuce and kale.

Effect of cold storage and harvest date on bioactive compounds in curly kale ( Brassica oleracea L. var. acephala)

In this study, curly kale stored at 1 °C for 3 and 6 weeks was compared with plants remaining in the field regarding several properties related to human health and sensory quality. Cold storage had no effect on the antioxidant capacity (ORAC assay), total phenols (Folin-Ciocalteu assay) or flavonol content, but reduced the content of vitamin C and soluble sugars. The ratio ascorbic:dehydroascorbic acid decreased from about 3 to 0.5 upon storage. The largest changes in the content of bioactive compounds were found in plants that remained in the field for 6 additional weeks, including many frost days. In these plants, the levels of flavonols, total phenols and antioxidant capacity were reduced by 25–35% and the vitamin C content by more than 50%, whereas soluble sugars and dry matter increased by roughly 20% and 30%, respectively. Among all the curly kale samples, the antioxidant capacity was positively correlated with the level of total phenols ( r = 0.73, P < 0.001) and total flavonols ( r = 0.70, P < 0.001). Values obtained with a non-destructive method based on chlorophyll fluorescence (ChlF) were well correlated with the flavonol content in the leaves, with the highest correlation found for quercetin ( r = 0.76, P < 0.001). Using the ChlF method, the kinetics of the flavonol content during the experiment was recorded. The same method also showed gradients of flavonol content within the plant, with the highest values in the upper leaves and in the tip of the leaves. ChlF measurement, therefore, proved to be a quick and cost-effective alternative to chemical analyses of the flavonol content in curly kale.

Dry Matter Content and Stability of Carotenoids in Kale and Spinach During Drying

Drying of spinach (Spinacia oleracea L.) and kale (Brassica oleracea L. var. acephala D.C.) is required to determine percentage of dry matter (%DM) and pigment concentration of fresh leaves. ‘Melody’ spinach and ‘Winterbor’ kale were greenhouse-grown in hydroponic nutrient solutions containing 13 or 105 mg·L−1 N. Using vacuum freeze dryers and convection ovens, plant tissues were dried for 120 h at five different temperature treatments: 1) freeze drying at −25 °C; 2) freeze drying at 0 °C; 3) vacuum drying at +25 °C; 4) oven drying at +50 °C; and 5) oven drying at +75 °C. Spinach leaf tissue %DM was affected, but kale %DM was unaffected by drying temperature. Spinach and kale leaf tissue %DM were both affected by N level. The high N spinach decreased from 7.3 to 6.4%DM when drying temperature increased from +25 to +75 °C. The low N spinach decreased from 12.7 to 9.6%DM as the drying temperature increased from −25 to +50 °C. Kale averaged from 14.8%DM for the high N treatment and from 21.8%DM for the low N treatment. However, drying temperature did not have a significant impact on measured %DM in kale. Lutein, β-carotene, and chlorophyll levels for both spinach and kale leaf tissue were affected by drying temperature. Measured concentrations of all pigments decreased over 70% as the drying temperature increased from −25 to 75 °C. The largest pigment fresh and dry weight concentrations for spinach and kale were measured at drying temperatures below +25 °C. The spinach and kale samples dried between −25 and +25 °C were not significantly different from each other in %DM or pigment concentration measured on a dry or fresh weight basis. Thus, drying leaf tissue for accurate pigment analysis requires temperatures below +25 °C using vacuum or freeze drying technology.

A practical approach to managing the risks of iodine deficiency in flocks using thyroid-weight:birthweight ratios of lambs

AIM: To establish a protocol for determining the iodine status of a flock and managing the risks of iodine deficiency, using thyroid-weight:birthweight ratios of newborn lambs and serum iodine concentrations of ewes. METHODS: Data were collected from iodine supplementation studies in Southland and Rangitikei, of sheep fed exclusively pasture or pasture plus brassica during the latter half of gestation (n=350, or 89 per treatment group). The ewes were supplemented pre-mating or at the time of pregnancy scanning with an injection of long-acting iodised oil. Serum iodine concentrations were measured in ewes prepartum in Rangitikei and postpartum at both locations. The thyroid-weight:birthweight ratios (as g/kg) in 229 newborn lambs were determined at post-mortem examination and compared between iodine supplemented vs unsupplemented flocks using probit analysis. Samples of pasture and kale were analysed monthly for determination of iodine and selenium. RESULTS: Initial mean serum iodine concentration of all ewes was 41 µg iodine/L. Supplementation increased serum iodine concentrations regardless of forage fed, and concentrations remained high for between 127 and 206 days. The range of thyroid-weight:birthweight ratios in lambs from supplemented ewes was 0.09–0.70 (mean 0.35, standard deviation (SD) 0.147) g/kg. Among lambs from unsupplemented ewes, the range was much wider (0.21–8.5; mean 1.61, SD 1.95 g/kg). About half of those ratios were >0.8 g/kg and clearly indicative of goitre, including 62% from the groups on brassica and 18% from the Rangitikei group fed exclusively pasture. Probit calculations showed that a ratio of 0.40 (95% confidence interval (CI)=0.29–0.47) g/kg predicted with 35% probability, and a ratio of 0.80 (95% CI=0.70–0.99) g/kg predicted with 90% probability that a lamb came from an unsupplemented flock. CONCLUSIONS: Compared to iodine concentrations in forages, thyroid-weight:birthweight ratios more accurately reflected the iodine status of the flock and could be used to identify which flocks to supplement the following year. Serum iodine concentrations of ewes measured before or after lambing did not reflect forage fed, but values near 40 µg/L were associated with goitrous lambs. CLINICAL RELEVANCE: Thyroid-weight:birthweight ratios >0.8 g/kg were indicative of iodine deficiency, and ewes should be supplemented pre-mating or during pregnancy to prevent goitre the following year. Ratios <0.4 g/kg rarely occurred among deficient flocks, so the probability of benefit from supplementation was low. Intermediate ratios were ambiguous, and the iodine status of the flock could not be determined from biomarkers. In such cases individual-farm supplementation trials might be required to detect and manage the risks of marginal deficiency.

Uptake of thallium from artificially contaminated soils by kale (Brassica oleracea L., var. acephala)

A pot experiment focused on the study of factors influencing thallium transfer from contaminated soils into kale (green cabbage, Brassica oleracea L. var. acephala, variety Winterbor F1) was evaluated. Three different types of topsoils with naturally low content of thallium (heavy, medium and medium-light soil) were used for pot experiments. The soils were contaminated with thallium sulfate to achieve five levels of contamination (0, 0.52, 2.10, 4.20 and 5.88 mg/kg). There were six replicates for each combination (90 pots in the experiment). The first part of the experiment started in the year of contamination (2001) and continued in 2003. The soil samples and the samples of kale (leaves and stalks were sampled separately) were collected and analysed. Kale was found to be able to accumulate Tl without any influence on yield. The highest thallium concentration was found in the leaves of kale in the first year of the experiment and reached 326 mg/kg dry matter. Bioaccumulation factor (Biological Absorption Coefficient &amp;ndash; BAC) was found to be over 80 during the first year of the experiment. In the third year the BAC was around 3 for the soil with the highest pH and the highest organic matter content but as high as 15 for an acid soil with the lowest content of organic matter and the lowest Cation Exchange Capacity (CEC) of soils. The content of thallium in the leaves of kale was found to be 7 to 10 times higher than in the stalks in the third year. In the first year this ratio was up to 18. From these findings it can be concluded that the ability of some plants of Brassicacea family, that are planted as common vegetables, to accumulate thallium is very high and can be a serious danger for food chains. Neutral soils high in CEC and organic matter are able to bind thallium more effectively than poor acid soils and the transfer of Tl into plants from these soils is substantially lower. The uptake of Tl from contaminated soils into kale can be very high and without any negative effect on the plant growth. The transfer of Tl into kale decreases with the time necessary to reach the equilibrium between the added Tl and the soil (ageing of a sample).

Iron Quadrangle, Brazil: Elemental concentration determined by k0-instrumental neutron activation analysis Part II: Kale samples

The objective of this study was to evaluate the influence of mining activity on elemental concentrations in kale grown around a mining area. Two sites studied are in the Iron Quadrangle, Minas Gerais, Brazil, considered one of the richest mineral-bearing regions in the world. One site is near mineral exploration activity and the other is an ecological area. A comparator site outside the Iron Quadrangle was also analyzed. This work focused on the determination of the elemental concentrations in kale applying the k0-instrumental neutron activation analysis. As the Brazilian legislation specifies values for soil only, the results for kale were compared to the literature values and it was found that the vegetable does not present any health risks.

Structural characterization and detection of kale flavonoids by electrospray ionization mass spectrometry.

Sensitive and precise analytical methods are needed for flavonols, a subclass of flavonoids that has strong antioxidant activity. We report an improved method for identifying the predominant flavonols, quercetin and kaempferol, by collisionally activated dissociation (CAD) and quantifying them by high-performance liquid chromatography electrospray ionization mass spectrometry (HPLC-ESI-MS) in the selected ion monitoring mode. Practical applications of the method were demonstrated using several kale and biological samples. Two commercial kale samples were found to have 77 or 244 ppm quercetin and 235 or 347 ppm kaempferol (ppm = microg of quercetin/g of kale or microg of kaempferol/g of kale by fresh weight, 5-15% relative standard deviation). Blanching was found to reduce the flavonols to approximately 60% of the levels found in the unblanched kale. Isotopically labeled kale (cultivar Vates) grown in a greenhouse under an atmosphere of (13)CO(2) was found to have much lower flavonol levels. UV-A and UV-B supplementation during kale growth in the greenhouse was found to enhance both quercetin and kaempferol levels in Vates kale. The UV-B-supplemented kale not only produced more flavonols but the quercetin-to-kaempferol ratio was also higher than the UV-A-supplemented or the nonsupplemented kale. Recovery of flavonols from kale was approximately 60% based on spike and recovery trials with rutin, a glycoside of quercetin. Recovery of flavonols from biological samples spiked with rutin ranged from 96% for urine to 70% for plasma. Compared to UV detection, ESI-MS in the deprotonation mode provided lower detection limits, and both higher sensitivity and selectivity, in addition to structural characterization of the kale flavonols by CAD.

The contamination of feed, fruits and vegetables with benzo(a)pyrene in Land Brandenburg

Benzo(a)pyren (BaP) was analysed in 218 samples of grass, hay, straw, grains, lettuce, curly kale and apples by means of thin-layer chromatography und analysing other polycyclic aromatic hydrocarbons (PAH) by capillary gas chromatography and mass-spectrometry. Despite the fact that normally BaP concentrations were relatively low, up to 13.5 micrograms BaP per kg hay (dry matter) and 19.3 micrograms BaP per kg lettuce (dry matter) could be detected at some places.

Reference materials for PAHs in foodstuffs: II. Results of a further intercomparison of methods in experienced laboratories

A preliminary intercomparison of methods which can be applied to the determination of trace amounts of PAHs in coconut oil and green kale samples has been made under an interlaboratory cooperative analytical programme organised by the Community Bureau of Reference. The techniques which were utilised were glass-capillary gas chromatography with flame-ionisation or mass spectrometric detection, and high-performance liquid chromatography with fluorescence and/or ultra-violet detection. Analyses were made for five environmentally important PAHs and the results, the methods and some associated problems are discussed.

Urea Enzymatic Dialysis Procedure for Determination of Total Dietary Fiber

A method that uses urea and enzymes for determination of total dietary fiber (TDF) in foods has been developed and compared with the AOAC enzymatic-gravimetric method (43.A14-43.A20). In the evaluation, results for crude protein and ash contamination were higher by the AOAC method, particularly for samples that form gels during ethanol precipitation. The new urea enzymatic dialysis (UED) method quantitatively recovered, with less variation, more of the purified and semipurified dietary fiber products. TDF recoveries for carboxymethylcellulose and locust bean gum were 98% (SD 3.3) and 95% (SD 6.1) by the AOAC method and 99% (SD 1.0) and 100% (SD 0.6) by the UED method, respectively. The UED method was the more effective in removing starch. For kale samples, starch recovery was 3.5 and 0.2% from TDF residues obtained using the AOAC and UED methods, respectively. Differences were not significant among replicate values for determination of TDF in foods by the UED method (P greater than 0.01). Preliminary studies suggest that the new method can separately determine soluble and insoluble dietary fiber. The data indicate that the UED method is more precise and accurate than the AOAC method.

A rapid screening method for determining the digestibility of kale using near infrared reflectance

AbstractA Neotec Scanning Infrared Analyser was used to generate predictive equations for the rapid estimation of kale digestibility. The most successful of these equations gave estimates of digestibility of samples in a calibration population that correlated highly (r=0.95) with the manual estimates. When this method was applied to additional kale samples, not included in the calibration set, it was again successful in screening for high digestibility, despite lower correlation coefficients and increases in standard errors as compared to the equivalent results for the calibration set. Absorption peaks in the spectral scans of cell wall components were compared with the wavelengths used in the best prediction equation in an attempt to gain a clearer understanding of the factor or factors that limit kale digestibility.

An evaluation of near infra-red reflectance analysis in some plant breeding programmes

SUMMARYSome applications of near infra-red reflectance (NIR) analysis in plant breeding have been tested. Prediction of the nitrogen content of cereals, kale and beans, and nitrogen and oil in rapeseed was sufficiently accurate for screening purposes although wheat straw gave a less accurate result. The prediction of nitrogen content of wheat grain could be supplemented by the simultaneous estimation of grinding resistance and bran cleanliness, characters of importance for bread-making quality. Hagberg falling number, sodium dodecyl sulphate (SDS) sedimentation volume and loaf volume could not be accurately predicted by NIR. Encouraging results were obtained for predicting malting quality of barley and the digestibility of kale samples.

Improvements in the approximate determination of S‐methylcysteine sulphoxide (kale anaemia factor)

AbstractThe S‐methylcysteine sulphoxide in kale samples was determined by ethanolic extraction and thin layer chromatography of the crude extract. The separated compound reacted with ninhydrin giving a colour which was interpolated visually in a series of colours produced by standards run on the same plate. Results by this approximate procedure are compared with those found by exhaustive aqueous extraction and automatic amino acid analysis by ion‐exchange chromatography.

Stability of Metallic Ethylene Bisdithiocarbamates in Chopped Kale

Abstract Chopped kale samples were fortified with maneb, zineb, or Dithane M-22, a maneb formulation. Samples were stored in a freezer or refrigerator and analyzed daily for 3 days. Using the carbon disulfide evolution procedure, the dithiocarbamate content in the samples was determined. Zineb was more stable than maneb or Dithane M-22 in both the frozen and refrigerated state. Immediately upon mixing, there was a loss of about 10% Dithane M-22 and 25% maneb. Freezing the samples prevented further losses.

An Investigation into the Possible Oestrogenic Effect of Kale

SUMMARY The possible oestrogenic effect of kale was investigated by the biological assay in rats of kale extracts. Neither oral administration nor subcutaneous injection of acetone extracts demonstrated the presence of oestrogenic activity in the kale samples used. There was no difference in response to an acetone extract and an extract obtained by alkaline alcoholic distillation when both were given by subcutaneous injection.