Melon peel flour: utilization as a functional ingredient in bakery products

Food by-products are a major concern with a direct impact on the economy, society, and environment. The valorisation of these by-products could be an advantageous approach to face the increase in food waste since it can compromise environmental health and food sustainability. On the other hand, this valorisation would allow the development of new food products with health benefits for the population. Cucumis melo L. is a highly consumed fruit all over the world since it has excellent sensory and nutritional qualities, being also a good source of bioactive compounds. However, its peel and seeds are usually discarded. The aim of this study was to evaluate the potential of melon peel flour as a functional ingredient for innovative food products. For that, two different formulations containing melon peel flour were developed (a biscuit and a muffin) by replacing a conventional flour (wheat flour) in different percentages (50% and 100%, respectively). The nutritional composition, total phenolic content, and antioxidant potential of the developed products were studied, showing a high content of fibre, high levels of phenolic compounds and good sensory acceptability. These results show that it is possible to enrich different foods with melon peel flour in order to improve their nutritional properties, contributing to improving public health, simultaneously valorising a usually rejected by-product, reducing food waste and the environmental impact.

The Health Effects of Low Glycemic Index and Low Glycemic Load Interventions on Prediabetes and Type 2 Diabetes Mellitus: A Literature Review of RCTs

Diets with a low glycemic index (GI) and a low glycemic load (GL) can improve glycemic control, blood lipids, blood pressure and BMI in prediabetes and type 2 diabetes (T2DM), but evidence regarding other aspects of cardiometabolic health is limited. We searched the literature for RCTs published from 2013 to 2023 and reviewed the evidence on low-GI/GL diets and their effects on different aspects of health in prediabetes and T2DM, aiming to build a report on all relevant outcomes included in the studies. We included 14 RCTs with 1055 participants, who were mostly middle-aged individuals with T2DM. Interventions were mostly low GI and lasted 1-36 months. Low-GI/GL foods and diets showed benefits in terms of short-term glycemic control, weight and adiposity. Longer-term trials would be necessary to determine whether these benefits persist over time and/or lead to lower CVD risk and mortality. Effects on lipid profile were inconsistent. Some studies also reported positive effects of low-GI/GL interventions on blood pressure, inflammatory biomarkers, renal function and gut microbiota composition. Future trials should focus on some of these novel outcome measures, which may provide important insights into the metabolic effects of low-GI diets on individuals with diabetes.

Oxalate in Foods: Extraction Conditions, Analytical Methods, Occurrence, and Health Implications

Oxalate is an antinutrient present in a wide range of foods, with plant products, especially green leafy vegetables, being the main sources of dietary oxalates. This compound has been largely associated with hyperoxaluria, kidney stone formation, and, in more severe cases, systematic oxalosis. Due to its impact on human health, it is extremely important to control the amount of oxalate present in foods, particularly for patients with kidney stone issues. In this review, a summary and discussion of the current knowledge on oxalate analysis, its extraction conditions, specific features of analytical methods, reported occurrence in foods, and its health implications are presented. In addition, a brief conclusion and further perspectives on whether high-oxalate foods are truly problematic and can be seen as health threats are shown.

Processed Food: Nutrition, Safety, and Public Health

Food processing comprises the activities involved during the transformation of raw materials from different origins (vegetable, animal) until a final product is achieved that is suitable for human consumption [...].

Association between myocardial mechanical dispersion and ventricular arrhythmogenicity in chagas cardiomyopathy

Chagas disease is a major health concern in Latin America. Ventricular arrhythmia (VA) is a hallmark of Chagas cardiomyopathy (CCM), associated with worse prognosis. The present study aimed to verify the association between myocardial mechanical dispersion (MD) and ventricular arrhythmogenicity in CCM. In a cross-sectional study, 77 patients (55.8 ± 10.4 years) with CCM were evaluated. Global longitudinal strain (GLS) and MD were assessed by echocardiography, derived from the speckle tracking technique. Myocardial MD was measured from the onset of the Q/R wave on electrocardiogram to the peak longitudinal strain in 16 segments of the left ventricle. Frequency and complexity of ventricular extrasystoles (VES) were assessed by dynamic electrocardiography. The density and complexity of VES and the presence of non-sustained ventricular tachycardias (NSVTs) increase as MD increases. In logistic regression, MD was the only variable associated with the presence of paired VES and ventricular bigeminy. In addition, both MD and GLS were associated with the presence of NSVT (both, p < 0.01), and MD was independently associated with NSVT (OR 1.04, 95% CI 1.004-1.201, p = 0.031). In CCM, MD is associated with a higher density and complexity of VES, including NSVT.

4-hydroxy-2-alkenals in foods: a review on risk assessment, analytical methods, formation, occurrence, mitigation and future challenges

Undoubtedly, significant advances were performed concerning 4-hydroxy-2-alkenals research on foods, and their formation by double oxidation of polyunsaturated fatty acids. But further studies are still needed, especially on their occurrence in foods enriched with n-3 and n-6 fatty acids, as well as in foods for infants and processed foods. Major factors concerning the formation of 4-hydroxy-2-alkenals were discussed, namely the influence of fatty acids composition, time/temperature, processing conditions, salt, among others. Regarding mitigation, the most effective strategies are adding phenolic extracts to foods matrices, as well as other antioxidants, such as vitamin E. Exposure assessment studies revealed 4-hydroxy-2-alkenals values that could not be considered a risk for human health. However, these toxic compounds remain unaltered after digestion and can easily reach the systemic circulation. Therefore, it is crucial to develop in vivo research, with the inclusion of the colon phase, as well as, cell membranes of the intestinal epithelium. In conclusion, according to our review it is possible to eliminate or effectively decrease 4-hydroxy-2-alkenals in foods using simple and economic practices.

Functional tests associated with sarcopenia in moderate chronic obstructive pulmonary disease

Objectives: To evaluate the association of physical and functional measures with sarcopenia in moderate chronic obstructive pulmonary disease (COPD) and to establish cutoff points for sarcopenia screening.Methods: The study included COPD with and without sarcopenia, of both sexes who were over 50 years old. Participants were assessed for lung function, body composition, grip strength, Short Physical Performance Battery (SPPB), 5-repetition, 10-repetition and 30-s sit-to-stand tests (5STS, 10STS, and 30STS, respectively). In addition, 6-min walking test, respiratory muscular strength, and physical activity level were tested.Results: The study had 35 participants, 24 men (68.6%) and moderate COPD (51.4%). COPD-sarcopenia showed lower values in lean mass, body fat and body mass alongside lower performance in 10 and 30 STS tests, SPPB and gait speed compared to non-sarcopenic group. The cutoff points with better sensitivity and specificity to identify sarcopenia were 10.88 and 34.14 s, 15 repetitions, and 10 points in the 5STS, 10STS, 30STS, and SPPB, respectively. The comparison of the receiver operating curves evidenced no differences between the functional tests. Only 30STS and SPPB showed acceptable discriminatory power.Conclusion: Functional tests, especially 30STS and SPPB, are simple and affordable tools for screening sarcopenia in COPD with moderate obstruction.

Compliance of declared vs. analysed values with EU tolerance limits for mandatory nutrients in prepacked foods

This study assessed compliance between declared and analysed values on prepacked foods, considering the tolerance limits for salt, fat and saturated fatty acids. Foods were distributed by food categories (e.g. snacks, ready-to-eat meals, potato and potato-products, bakery and pastry products) and a total of 209 products were analysed. Only half of the samples with a declared value ≥1.25 g/100 g were within tolerance limits for salt content. The lowest number of samples outside tolerance limits was observed for fat content; for saturated fatty acids, 27% of the samples were outside of tolerance limits. Only amongst "cereal products" were 100% of products compliant for fat and salt declarations. It is of utmost importance that manufacturers update continuously values declared for prepacked foods, because this information is crucial for consumers and food policy-makers as well as being a legal requirement.

Food Composition at Present: New Challenges

Food composition data is important for stakeholders and users active in the areas of food, nutrition and health. New challenges related to the quality of food composition data reflect the dynamic changes in these areas while the emerging technologies create new opportunities. These challenges and the impact on food composition data for the Mediterranean region were reviewed during the NUTRIMAD 2018 congress of the Spanish Society for Community Nutrition. Data harmonization and standardization, data compilation and use, thesauri, food classification and description, and data exchange are some of the areas that require new approaches. Consistency in documentation, linking of information between datasets, food matching and capturing portion size information suggest the need for new automated tools. Research Infrastructures bring together key data and services. The delivery of sustainable networks and Research Infrastructures in food, nutrition and health will help to increase access to and effective use of food composition data. EuroFIR AISBL coordinates experts and national compilers and contributes to worldwide efforts aiming to produce and maintain high quality data and tools. A Mediterranean Network that shares high quality food composition data is vital for the development of ambitious common research and policy initiatives in support of the Mediterranean Diet.

25 years of European Union (EU) quality schemes for agricultural products and foodstuffs across EU Member States

Consumers are increasingly turning their attention to the quality and origin of products that they consume. European Union (EU) quality schemes are associated with a label, which was introduced to allow consumers to perform an informed choice and to protect producers from unfair practices. This present study provides an overview of the last 25 years of EU quality schemes [Protected Designations of Origin (PDO), Protected Geographical Indications (PGI) and Traditional Specialities Guaranteed (TSG)] on agricultural products and foodstuffs across the 28 EU Member States. According to the results, it was possible to conclude that Southern European countries have the highest number of registered products. The most used EU quality scheme is PGI, followed by PDO. Concerning the analysis of the evolution in the last 25 years, the number of registered products among EU Member States has increased significantly. The fruit, vegetables and cereals (fresh or processed) category is the one that accounts for the highest percentage (26.8%) of registered products, followed by cheeses and meat products (cooked, salted, smoked) categories, with 17.2% and 13.5%, respectively. Further investigations should address consumer preferences, knowledge and attitudes, especially Northern European countries with a lower number of registered products. Moreover, the investigation and registration of products should be encouraged among all EU Member States to allow the maintenance of important elements of the history, culture and heritage of the local areas, regions and countries. © 2017 Society of Chemical Industry.

Multivariate characterization of salt and fat content, and the fatty acid profile of pastry and bakery products

The content of salt, fat and fatty acid profile of pastry and bakery products commercialised in Portugal was evaluated.

The impact of cooking methods on the nutritional quality and safety of chicken breaded nuggets

The impact of cooking methods (industrial pre-frying, deep-fat frying and baking) on the nutritional quality and safety of chicken breaded nugget samples from supermarket and commercial brands was evaluated. The changes in the quality characteristics (nutritional composition, fatty acids profile, cholesterol and salt) of the fried food and frying oil, after ten consecutive frying operations, were evaluated. The total fat content of nuggets varied between 10.9 and 22.7 g per 100 g of edible portion and the salt content ranged from 0.873 to 1.63 g per 100 g. Taking into account one portion of nuggets, the daily intake of salt can reach 49%, which can have a significant impact on the health of those who regularly consume this type of food, especially considering the prevalence of hypertension around the world. The analysed chicken breaded nuggets are rich in unsaturated fatty acids, which have been related with potential health benefits, namely regarding cardiovascular diseases. The cholesterol content of baked samples was two times higher when compared with the fried ones. The trans fatty acids and polar compounds contents of the frying oil used for frying significantly increased, but the values were still away from the maximum recommended by legal entities for its rejection. From a nutritional point of view, it is possible to conclude that the applied cooking methods can significantly influence the nutritional quality and safety of the analysed chicken breaded nuggets. This study will contribute to important knowledge on how the applied cooking methods can change the nutritional quality and safety of foods, namely of chicken nuggets, and can be very useful for dietary recommendations and nutritional assessment.

Effect of UV-C radiation on bioactive compounds of pineapple (Ananas comosus L. Merr.) by-products

BACKGROUND

The industrial processing of pineapple generates a high quantity of by-products. To reduce the environmental impact of these by-products and the inherent cost of their treatment, it is important to characterise and valorise these products, converting them into high added value products. Ultra-violet radiation is one of the main sustainable sanitation techniques for fruits. Since this radiation can induce plant stress which can promote the biosynthesis of bioactive compounds, it is important to evaluate its effect in fruits.

RESULTS

The amounts of vitamins (C and E) and carotenoids (α-carotene, β-carotene, β-cryptoxanthin, lutein, lycopene, neoxanthin, violaxanthin and zeaxanthin) in pineapple by-products (core and rind) were analysed before and after treatment with UV radiation. All treated and untreated pineapple by-products contained β-carotene as the main carotenoid (rind, 2537-3225 µg; and core, 960-994 µg 100 g(-1) DW). Pineapple rind also contained lutein (288-297 µg 100 g(-1) DW) and α-carotene (89-126 µg 100 g(-1) DW).

CONCLUSION

The results provide evidence of the potential of pineapple by-products as a source of bioactive compounds with antioxidant activity, which can be used by pharmaceutical, cosmetics and food industries. In addition, UV-C was shown to be a treatment that can add nutritional value to pineapple by-products.

Cholesterol determination in foods: Comparison between high performance and ultra-high performance liquid chromatography

Analytical methods for cholesterol evaluation in foods are crucial since this compound was closely related with cardiovascular disease. In the present study, two chromatographic methods were implemented and validated, in order to achieve the ideal analytical method for the quantification of cholesterol in food matrices. The developed methods were applied to different foodstuffs, sour cream, egg, egg yolk and chicken nuggets. Both HPLC and UHPLC methods are rapid, specific, sensitive, precise (RSD<2.5%) and accurate. The achieved LOD and LOQ for UHPLC were 0.7 and 2.4μg/mL, respectively, while for HPLC were 3 and 11μg/mL. UHPLC method allowed reduction of the organic solvents consumption (8 times lower) and decreased analysis time in 4min, being more eco-friendly, than conventional HPLC methods. Moreover, it will be very useful for the quality control of cholesterol content in food matrices and can be easily adopted by analytical laboratories.

Nutritional and phytochemical composition of Annona cherimola Mill. fruits and by-products: Potential health benefits

Annona cherimola Mill., commonly known as cherimoya, is a tropical fruit well known due to its tasty flavour. In the present study the antioxidant activity of pulp, peel and seeds of four cultivars from A. cherimola Mill. from Madeira Island (Madeira, Funchal, Perry Vidal and Mateus II) was analysed. Moreover, nutritional composition (proximates and vitamins) and bioactive compounds content were determined. The peel of Madeira cultivar showed the highest antioxidant capacity, with an EC50 of 0.97mg/mL, and total flavonoids (44.7 epicatechin equivalents/100g). The most abundant carotenoid was lutein, with values ranging from 129 to 232μg/100g. The highest l-ascorbic acid content (4.41mg/100g) was found in the peel of Perry Vidal cultivar. These results highlight A. cherimola Mill. antioxidant properties, especially in its by-products and encourage their application in cosmetic, pharmaceutical and food processing industries, as added value natural extracts.

Trends in the use of natural antioxidants in active food packaging: a review

The demand for natural antioxidant active packaging is increasing due to its unquestionable advantages compared with the addition of antioxidants directly to the food. Therefore, the search for antioxidants perceived as natural, namely those that naturally occur in herbs and spices, is a field attracting great interest. In line with this, in the last few years, natural antioxidants such as α-tocopherol, caffeic acid, catechin, quercetin, carvacrol and plant extracts (e.g. rosemary extract) have been incorporated into food packaging. On the other hand, consumers and the food industry are also interested in active biodegradable/compostable packaging and edible films to reduce environmental impact, minimise food loss and minimise contaminants from industrial production and reutilisation by-products. The present review focuses on the natural antioxidants already applied in active food packaging, and it reviews the methods used to determine the oxidation protection effect of antioxidant active films and the methods used to quantify natural antioxidants in food matrices or food simulants. Lastly consumers' demands and industry trends are also addressed.

Definition and documentation of traditional foods of the Black Sea Area Countries: potential nutrition claims

BACKGROUND

Nutrition and health claims are permitted in foods marketed in the European Union under Regulation 1924/2006. Quality products such as traditional foods might benefit from this act, as it can highlight their nutritional richness. In this study the nutritional content of 33 traditional foods from the Black Sea Area Countries was evaluated against the thresholds of the Regulation for nutrition claims.

RESULTS

Most of the foods were eligible to bear several nutrition claims, mostly related to their fat, sugar, fiber and sodium content. The average number of claims per traditional food was two, with a range between zero and nine. Overall, about 72 nutrition claims were potentially relevant for the 33 traditional foods studied. Foods linked with the most claims were nuts and seeds.

CONCLUSION

The inclusion of traditional foods under this standardized European scheme could be an efficient way to highlight their possible beneficial nutritional properties. The production and marketing of traditional foods could be of benefit to both the health of consumers and the economic viability of producers, especially small- and medium-size enterprises.

New nutritional composition data on selected traditional foods consumed in Black Sea Area countries

BACKGROUND

Traditional foods are an important part of the culture, history, identity and heritage of a region or country and are key elements in dietary patterns. In most countries there is limited information on the nutritional composition of such foods and therefore there is a need to investigate, register and promote traditional foods. One of the aims within the 'Sustainable exploitation of bioactive components from the Black Sea Area traditional foods' (BaSeFood) project is to generate for the first time new data on the nutritional composition of traditional foods from six Black Sea Area countries to promote their sustainable development and exploitation.

RESULTS

Thirty-three traditional foods were analysed in an accredited laboratory to determine their nutritional composition, and the data were fully documented. The nutrient content varied widely because of the nature and variety of the analysed foods. The energy content ranged between 4 kcal per 100 g for kvass southern and 900 kcal per 100 g for mustard oil, with the exception of the analysed teas, which did not contribute to energy intake.

CONCLUSION

The use of a common methodology for the study of traditional foods will enable countries to further investigate these foods. Moreover, a new nutritional knowledge base of traditional foods from Black Sea Area countries will contribute to promote local biodiversity and sustainable diets by maintaining healthy dietary patterns within local cultures.

Comparison of leafy kale populations from Italy, Portugal, and Turkey for their bioactive compound content: phenolics, glucosinolates, carotenoids, and chlorophylls

BACKGROUND

Kales are primitive leafy Brassica oleracea L. forms, widespread in local farming systems of several European countries and employed in the preparation of traditional recipes. Kales are also potential sources of healthy bioactive phytochemical components. The present study compared the bioactive compound content of kale populations from Italy, Portugal, and Turkey, either from local sources or grown in an experimental field.

RESULTS

Total phenolics, glucosinolates (GLS), carotenoids, and chlorophylls were in the ranges 8310-38 110, 755-8580, 135-2354, and 1740-16,924 mg kg(-1) dry matter, respectively. On average, locally harvested samples showed a total GLS content about twice as high as populations from the experiment. Conversely, pigments were significantly more abundant in experimental than in local kales, owing to the higher soil fertility. Portuguese samples showed higher phenolic and GLS amounts than Italian and Turkish kales, whereas some of the Italian samples were the richest in carotenoids.

CONCLUSION

This paper represented the first cross-country comparison of local kale accessions with respect to bioactive compound amounts. Both geographic origin and growing environment appeared to be remarkable and discriminating factors in determining bioactive levels in leafy kales, with possible effects on their health-promoting and sensorial attributes.

Carotenoids, vitamins (A, B2, C and E) and total folate of traditional foods from Black Sea Area countries

BACKGROUND

Carotenoids, vitamins (A, B2, C and E) and total folate are related to health promotion. However, there are still many food matrices for which the content of these compounds is not available. In order to fill this gap, traditional foods from Black Sea Area countries (BSAC) were analysed in order to investigate their potential health benefits.

RESULTS

The most abundant carotenoid was β-carotene. Plum jam was the sample with the highest β-carotene content (608 µg 100 g(-1) edible portion). The group of vegetables and vegetable-based foods contributed most to β-carotene content. Evergreen cherry laurel presented the highest l-ascorbic acid content (29.9 mg 100 g(-1) edible portion), while the highest riboflavin and total folate contents were found for roasted sunflower seeds. Approximately 61% of the analysed samples showed quantifiable amounts of α-tocopherol but did not contain retinol.

CONCLUSION

Despite the great variability in the content of carotenoids, vitamins and total folate, most of the analysed traditional foods from BSAC can be considered good sources of these compounds. Therefore, owing to their putative health benefits, the consumption of those with higher contents of these compounds should be encouraged and promoted.

Traditional foods from the Black Sea region as a potential source of minerals

BACKGROUND

In the past few years, minerals have assumed great importance in public health. As a consequence, considerable research has been carried out to better understand their physiological role and the health consequences of mineral-deficient diets, to establish criteria for defining the degree of public health severity of malnutrition, and to develop prevention and control strategies. In most countries, there is limited information on the mineral content of traditional foods, and consequently it is very difficult to estimate mineral intake across these countries.

RESULTS

Ten minerals were quantified in 33 traditional foods from Black Sea area countries. Our results indicate a considerable variability among the analysed traditional foods; nevertheless, the most abundant components were sodium (ranging from 40.0 to 619 mg 100 g(-1), for kvass southern and herbal dish, respectively), potassium (varied between 45.5 mg 100 g(-1) for millet ale and 938 mg 100 g(-1) for roasted sunflower seeds), and phosphorus (22.2 mg 100 g(-1) and 681 mg 100 g(-1) for sauerkraut and roasted sunflower seeds, respectively).

CONCLUSION

This is the first study that provides validated data on the mineral content for 33 traditional foods from Black Sea area countries, which is important in order to elucidate their role in the dietary pattern of populations and to preserve and promote these foods.

Ultra-high pressure LC determination of glucosamine in shrimp by-products and migration tests of chitosan films

Chitosan, a multiple applications molecule, was isolated from shrimp by-products by fermentation. The amount of chitosan in the solid fraction of the fermented extract was measured after its conversion in the respective glucosamine units. The procedure includes an acid hydrolysis (110 °C, 4 h with HCl 8 M) and a derivatization with 9-fluorenylmethyl chloroformate (Fmoc-Cl). Ultra-high-pressure liquid chromatography method was developed and optimized. Excellent peaks resolution was achieved in just 10 min. The method was evaluated in what concerns to validation parameters such as linearity, repeatability, quantification limit, and recovery. Migration tests of films prepared with chitosan were carried out in two simulants: ultrapure water and ethanol 95% (v/v).

An update on potato crisps contents of moisture, fat, salt and fatty acids (including trans-fatty acids) with special emphasis on new oils/fats used for frying

Eighteen brands of potato crisps, frequently consumed, were analyzed to establish their nutritional value in relation to salt, fat and fatty acid (FA) composition. The purpose of the present study was to determine moisture, total fat, salt contents and FA profiles (including trans-FAs), and to identify the oil/fat used for frying of the 18 brands of potato crisps. Our results show that salt content ranged from 0.127 to 2.77 g/100 g and total fat content of potato crisps varied between 20.0 and 42.8 g/100 g. With respect to FAs analysis, palmitic acid (C16:0), oleic acid (C18:1) and linoleic acid (C18:2) were the major FAs found in the analyzed potato crisps. It is clear from our work that nowadays most potato crisps are currently produced using oils with high contents in unsaturated FAs, which can be considered as healthier from a nutritional point of view. Nevertheless, some brands of potato crisps still use palm oil or a blend of palm oil and other fats/oils, which are very rich in saturated FAs.

Differentiation of Strains of Xylella fastidiosa Infecting Grape, Almonds, and Oleander Using a Multiprimer PCR Assay

Xylella fastidiosa is a xylem-limited, nutritionally fastidious bacterium that causes several plant diseases including Pierce's disease (PD) in grape and leaf scorch in almond (ALS) and oleander (OLS). OLS strains belong to X. fastidiosa subsp. sandyi, PD strains belong to X. fastidiosa subsp. fastidiosa, and strains from almond designated as ALS strains are of two general types belonging either to X. fastidiosa subsp. multiplex or X. fastidiosa subsp. fastidiosa. The ALS strains assigned to X. fastidiosa subsp. multiplex belong to two different genotypes (ALSI and ALSII) below the subspecies level. The OLS strains do not infect grape or almond. PD strains produce diseases in grape, alfalfa, almond, and some weeds, but they do not infect oleander, oak, peach, or citrus. ALS strains that belong to X. fastidiosa subsp. multiplex do not produce disease on grape. In this study, a relatively simple polymerase chain reaction (PCR) based method was developed to distinguish among PD, OLS, and ALS strains. PCR performed with primers XF1968-L and XF1968-R amplified a 638-bp fragment from OLS strains but not from PD strains or ALS strains that belong to X. fastidiosa subsp. fastidiosa. PCR with primers XF2542-L and XF2542-R amplified a 412-bp fragment from PD strains, but not from OLS strains. PCR with primers ALM1 and ALM2 produced a fragment of 521 bp from strains isolated from almond that belong to X. fastidiosa subsp. multiplex. The combination of the three primer sets allowed the distinction of the two ALS genotypes of X. fastidiosa subsp. multiplex. These results are in agreement with those obtained from analysis of sequences of 16S-23S rDNA intergenic spacer regions sequence analysis and with previous results based on randomly amplified polymorphic DNA analysis.

Discovery and Characterization of Xylella fastidiosa Strains in Southern California Causing Mulberry Leaf Scorch

Mulberry leaf scorch (MLS), caused by Xylella fastidiosa, is a disease of mulberry trees in the United States that has largely been documented from locations in the eastern and central areas of the country. MLS was recently detected for the first time in white mulberry (Morus alba) trees in southern California. Four MLS-strains were isolated from two locations and confirmed as X. fastidiosa by enzyme-linked immunosorbent assay (ELISA), direct isolation of the pathogen, and use of the X. fastidiosa-specific PCR primers RST31-33. Isolated strains were characterized by the sequencing of their 16S-23S rDNA intergenic spacer regions (ISR) and random amplified polymorphic DNA (RAPD) analysis and subsequent comparison with a previously characterized MLS-strain (Mulberry-VA) and representatives of X. fastidiosa subsp. fastidiosa, X. fastidiosa subsp. multiplex, and X. fastidiosa subsp. sandyi. MLS-strains isolated from California were distinct from strains causing almond leaf scorch, oleander leaf scorch, and Pierce's disease and similar to the Mulberry-VA-strain. The ISR sequences of two MLS-strains, MLS063 and MLS059, were 100% identical to that of the Mulberry-VA sequence, whereas MLS012 and MLS024 were 99.8 and 99.6% identical to the Mulberry-VA-strain and 99.4% identical among themselves. Genomic analysis using RAPD revealed no differences among the four strains. The pathogenicity of one strain, MLS063, was confirmed by inoculation of glasshouse-grown white mulberry plants. Three months after inoculation, the pathogen was recovered from 21 of 25 inoculated plants, and 5 of 25 plants were dead within a year of inoculation. Inoculation of grapevines and oleanders with MLS063 did not result in any disease or recovery of the pathogen up to 1 year later, showing that this strain was not cross-infective to these hosts.

Detection and differentiation of Xylella fastidiosa strains acquired and retained by glassy-winged sharpshooters (Hemiptera: Cicadellidae) using a mixture of strain-specific primer sets

Xylella fastidiosa Wells is a bacterial pathogen that causes a variety of plant diseases, including Pierce's disease (PD) of grapevine, almond leaf scorch, alfalfa dwarf, citrus variegated chlorosis, and oleander leaf scorch (OLS). Numerous strains of this pathogen have been genetically characterized, and several different strains occur in the United States. The dominant vector in southern California is the glassy-winged sharpshooter, Homalodisca coagulata (Say) (Hemiptera: Cicadellidae). The high mobility of this insect, and its use of large numbers of host plant species, provides this vector with ample exposure to multiple strains of X. fastidiosa during its lifetime. To learn more about the ability of this vector to acquire, retain, and transmit multiple strains of the pathogen, we developed a polymerase chain reaction (PCR)-based method to detect and differentiate strains of X. fastidiosa present in individual glassy-winged sharpshooter adults. Insects were sequentially exposed to plants infected with a PD strain in grapevine and an OLS strain in oleander. After sequential exposure, a few insects tested positive for both strains (7%); however, in most cases individuals tested positive for only one strain (29% PD, 41% OLS). In transmission studies, individual adults transmitted either the PD or OLS strain of the pathogen at a rate (39%) similar to that previously reported after exposure to a single strain, but no single individual transmitted both strains of the pathogen. PD and OLS strains of X. fastidiosa remained detectable in glassy-winged sharpshooter, even when insects were fed on a plant species that was not a host of the strain for 1 wk.

Plant Hosts of Xylella fastidiosa In and Near Southern California Vineyards

Xylella fastidiosa is a xylem-limited bacterium that causes Pierce's disease (PD) of grapevines. A variety of plant species found near a severe outbreak of PD in vineyards in the Temecula Valley of California were tested using enzyme-linked immunosorbent assay, culture on media, and polymerase chain reaction to identify potential inoculum sources in the area. Species that consistently tested positive for X. fastidiosa were the known hosts, grape, almond, and oleander, and two new hosts, Spanish broom (Spartium junceum) and wild mustard (Brassica spp). Sequence analysis of the 16S-23S rRNA spacer region found that strains isolated from grapevine, Spanish broom, wild mustard, and almond clustered with previously sequenced PD strains. Thus, these species could serve as sources of inoculum for infection of grapevines and should be removed or monitored for signs of infection. Sequences from oleander isolates from Temecula formed another cluster with a previously published oleander strain sequence. Oleander strains do not infect grapevines and thus do not appear to cause a direct threat to grapevines. Two additional isolates from almond were determined to be genetically different from PD strains, and the ability of these strains to infect grapevine is not known. Greenhouse transmission studies indicate that the glassy-winged sharpshooter was able to transmit a PD strain of X. fastidiosa to Spanish broom, black mustard, and other hosts.

The need for reference materials when monitoring nitrate intake

Whether dietary exposure to nitrate metabolites is detrimental or beneficial to human health has long been a matter of controversy. In spite of no consistent epidemiological evidence, nitrate metabolites are associated with the formation of carcinogenic-nitrosamines and gastric cancer. Furthermore, recent studies demonstrate that ingested nitrate plays a role in host defence against gastrointestinal pathogenic bacteria. Analytical values of nitrate content in foods are essential for estimating nitrate intake. The analytical process is of paramount importance for assessing human nitrate exposure and for establishing a link between these exposures and the current and future observed health effects. Therefore, the quality assurance of the measurement process is crucial to obtaining reliability, comparability and traceability of results. Certified Reference Materials (CRM) should play a role in the consistency of the measurement process. However, the availability of nitrate CRMs is still poor. When food monitoring is demanded, an approach could be to use In House Reference Materials (IHRM), prepared at a high metrological level, and all preparation steps should be quality driven. IHRMs were prepared, and available CRMs were used to provide traceability of the process. The homogeneity of IHRM was evaluated using an appropriate statistical design. The stability was monitored using an isochronous method. The material shelf life and storage conditions are presented. HPLC was optimised for the determination of nitrates in four vegetable categories. When a suite of IHRMs were used, the response of the HPLC system was linear over the range 1 to 8 mg L(-1). The detection limit for these compounds was 0.2 microg L(-1) and the determination limit 1.2 microg L(-1). The relationship between measurement uncertainty and critical points of the analytical process is presented. The differences in observed relative uncertainty between food categories could reflect current limitations in the food matrix reference materials.

Field trials measuring the effects of ultraviolet-absorbing greenhouse plastic films on insect populations

Field studies were conducted to compare insect population levels in greenhouse crops covered with plastics that block the transmission of UV light in two wavelength ranges. Crops grown in greenhouses under a plastic that blocked UV light at wavelengths of 380 nm and below had lower numbers of aphids and thrips compared with a plastic that blocked UV light at wavelengths of 360 nm and below. This is consistent with the results found for thrips in previous studies using small, completely enclosed tunnels with no plant material. The effects were not as dramatic in the commercial greenhouses, perhaps due to unfiltered light entering through the open sides of those greenhouses. There was no reduction in greenhouse whitefly, Trialeurodes vaporariorum Westwood, populations under the <380 UV-absorbing plastic compared to <360 nm UV-absorbing plastic in these field trials. This is inconsistent with results found in small, completely enclosed tunnels, where sticky traps caught a significantly higher proportion (95 +/- 2%) of released greenhouse whiteflies inside tunnels covered with <360 nm absorbing plastic compared with the <380 nm absorbing plastic. The results of these studies suggest that the type of greenhouse plastic used in a structure can affect population levels of some insect species, and may be useful tools in developing integrated pest management programs for insect management. The design of the greenhouse and amount of unfiltered light that enters the system appear to be important factors in determining the level of effect.

Seasonal flight activity of two Homalodisca species (Homoptera: Cicadellidae) that spread Xylella fastidiosa in southern California

Homalodisca coagulata (Say) and Homalodisca lacerta (Fowler) are vectors of a new bacterial disease of oleander in California known as oleander leaf scorch, induced by the bacterium Xylella fastidiosa. H. coagulata also has been implicated in the spread of the strain of X. fastidiosa that induces Pierce's disease of grapevines in California. We monitored the flight activity of H. coagulata and H. lacerta in oleander and citrus by using yellow sticky cards at three southern California locations where outbreaks of oleander leaf scorch have been documented, and where vector compliments are different. Areas sampled included a mesic coastal area (Irvine, CA) that supports predominantly H. coagulata and few H. lacerta, a dry inland location (Palm Desert, CA) that supports predominantly H. lacerta and few H. coagulata, and an intermediate area (Riverside, CA) supporting both Homalodisca species. From November 1996 to October 1999 peak catches of both Homalodisca species occurred during the midsummer at all locations. H. coagulata was trapped in greater numbers in citrus than in oleander at both the Riverside and the Irvine sites. Likewise, H. lacerta in Riverside was more associated with citrus than oleander, yet H. lacerta in Palm Desert was trapped in greater numbers in oleander than citrus.

Solution structure of plantaricin C, a novel lantibiotic

Plantaricin C, a bacteriocin produced by a Lactobacillus plantarum strain of dairy origin, is a lantibiotic. One dehydroalanine, one lanthionine and three beta-methyl-lanthionine residues were found in its 27 amino acid sequence. The plantaricin C structure has two parts: the first comprises the six NH2-terminal residues, four of which are lysines, which confer a strong positive charge to this stretch. The amino acids in positions 7 and 27 form the lanthionine bridge, giving a globular conformation to the rest of the molecule. The beta-methyl-lanthionine bridges are established between residues 12-15, 13-18 and 23-26. This central region has a charge distribution compatible with an amphipathic alpha-helix, through which plantaricin C would become inserted into the membrane matrix of sensitive organisms, provoking the opening of pores and leakage of the cytoplasmic content.

Cytochrome c" from the obligate methylotroph Methylophilus methylotrophus, an unexpected homolog of sphaeroides heme protein from the phototroph Rhodobacter sphaeroides

The complete primary structure of an unusual soluble cytochrome c isolated from the obligate methylotrophic bacterium Methylophilus methylotrophus has been determined to contain 124 amino acids and to have an average molecular mass of 14293.0 Da. The sequence has two unusual features: firstly, the location of the heme-binding cysteines is far downstream from the N-terminus, namely at positions 49 and 52; secondly, an extra pair of cysteine residues is present near the C-terminus. In both respects, cytochrome c" is similar to the oxygen-binding heme protein SHP from the purple phototrophic bacterium Rhodobacter sphaeroides. In contrast to SHP, cytochrome c" changes from low-spin to high-spin upon reduction, due to dissociation of a sixth heme ligand histidine which is identified as His-95 by analogy to the class I cytochromes c. The distance of His-95 from the heme (41 residues) and the presence of certain consensus residues suggests that cytochrome c" is the second example of a variant class I cytochrome c.

Solution structure of Desulfovibrio vulgaris (Hildenborough) ferrocytochrome c3: structural basis for functional cooperativity

Desulfovibrio vulgaris cytochrome c3 is a 14 kDa tetrahaem cytochrome that plays a central role in energy transduction. The three-dimensional structure of the ferrocytochrome at pH 8.5 was solved through two-dimensional 1H-NMR. The structures were calculated using a large amount of experimental information, which includes upper and lower distance limits as well as dihedral angle restraints. The analysis allows for fast-flipping aromatic residues and flexibility in the haem plane. The structure was determined using 2289 upper and 2390 lower distance limits, 63 restricted ranges for the phi torsion angle, 88 stereospecific assignments out of the 118 stereopairs with non-degenerate chemical shifts (74.6%), and 115 out of the 184 nuclear Overhauser effects to fast-flipping aromatic residues (62.5%), which were pseudo-stereospecifically assigned to one or the other side of the ring. The calculated NMR structures are very well defined, with an average root-mean-square deviation value relative to the mean coordinates of 0.35 A for the backbone atoms and 0.70 A for all heavy-atoms. Comparison of the NMR structures of the ferrocytochrome at pH 8.5 with the available X-ray structure of the ferricytochrome at pH 5.5 reveals that the general fold of the molecule is very similar, but that there are some distinct differences. Calculation of ring current shifts for the residues with significantly different conformations confirms that the NMR structures represent better its solution structure in the reduced form. Some of the localised differences, such as a reorientation of Thr24, are thought to be state-dependent changes that involve alterations in hydrogen bond networks. An important rearrangement in the vicinity of the propionate groups of haem I and involving the covalent linkage of haem II suggests that this is the critical region for the functional cooperativities of this protein.

Assignment of the ligand geometry and redox potentials of the trihaem ferricytochrome c3 from Desulfuromonas acetoxidans

Cytochrome c551.5 is a trihaem cytochrome of the cytochrome c3 family isolated from Desulfuromonas acetoxidans. Although several X-ray structures are available for tetrahaem cytochromes of this family, there is no X-ray structure for trihaem cytochromes. Cytochrome C551.5 was studied in the oxidized form by means of two-dimensional NMR. The pattern of observed interhaem NOESY connectivities is in agreement with the haem core structure previously determined by NMR for the reduced protein [Coutinho, I. B., Turner, D. L., Liu, M. Y., LeGall, J. & Xavier, A. V. (1996) J. Biol. Inorg. Chem. 1, 305-311]. The similarities found between the haem core structure and the amino acid sequence of cytochrome c551.5 and those of tetrahaem cytochromes c3 allows each of the haems to be specifically assigned in the polypeptide sequence, and the attribution of the midpoint redox potentials to the individual haems. This also allows individual redox potentials to be assigned to each haem in the NMR spectrum. The paramagnetic shifts of the 13C resonances of the haem substituents were analyzed in terms of pi molecular orbitals with perturbed D4h symmetry. The parameters of this analysis have been shown to be controlled by the orientation of the axial ligands in several other bis-His-coordinated haems and hence the ligand geometry was deduced for cytochrome C551.5. The structural analogy between the relative haem plane orientations in cytochrome c551.5 and the tetrahaem cytochromes c3 is found to extend to the axial ligands with the largest differences being in the vicinity of the deleted fourth haem, using the numbering of cytochrome c3 haems.

An unusual conformation of the methionine haem ligand in cytochrome cL established by two-dimensional 1H-NMR

A complete relaxation-matrix analysis of NOESY cross-peak intensities was used to determine the conformation of the methionine ligand to the haem group in two ferrocytochromes cL from Methylophilus methylotrophus and Methylobacterium extorquens, including the configuration at the sulphur. The conformation of the axial methionine is of a type reported only for the cytochromes c5 from Pseudomonas mendocina and Azotobacter vinelandii. Although the conformation of the methionine is unusual, the paramagnetic shifts of the haem methyl proton resonances in the oxidized proteins indicate that the electronic structure of the haem groups is similar to that found in the mitochondrial type of cytochrome c.

Characterization of the haem environment in Methylophilus methylotrophus ferricytochrome c" by 1H-NMR

Two-dimensional NMR techniques have been used to assign proton resonances in the haem cavity of Methylophilus methylotrophus cytochrome c", a monohaem protein with bis-histidinyl ligation which has been shown to couple electron and proton transfer. All the assignments were made directly for the oxidized paramagnetic form of the cytochrome. Nearly all of the haem protons (90%) and the protons of both axial ligands have been assigned; the side-chain protons from four other residues in the haem pocket have also been identified. The data indicate a highly symmetric unpaired-electron distribution in the haem group, which agrees with a perpendicular orientation of the axial imidazole planes. The two haem propionate groups have contrasting degrees of exposure to the solvent, with the propionate group at position 13 being highly exposed. To obtain information on the dynamics of the haem environment, measurements of the 1H/2H-exchange rates of amide protons located in the haem cavity were performed. The two faces of the haem are found to differ markedly with respect to water accessibility. All of this information, together with additional protein sequencing data, indicates that His52 remains attached upon reduction and that the redox-linked protonation occurs via a channel running through the haem cleft on the opposite face.

Pitfalls in assigning heme axial coordination by EPR. c-Type cytochromes with atypical Met-His ligation

Different monohemic c-type cytochromes were analyzed by visible, EPR and 1H NMR spectroscopies. While the visible and NMR data show unambiguously that the heme iron has a Met-His heme axial coordination, the EPR data indicate an axial ligand field typical of that for a bis-histidinyl ligation. The validity of the widely used EPR methods for the determination of the heme iron axial coordination, based on the crystal field parameters (tetragonality and rhombicity), is questioned.

Involvement of a labile axial histidine in coupling electron and proton transfer in Methylophilus methylotrophus cytochrome c''

Methylophilus methylotrophus cytochrome c'' is an unusual monohaem protein (15 kDa) undergoing a redox-linked spin-state transition [Santos, H. & Turner, D. L. (1988) Biochim. Biophys. Acta 954, 277-286]. The midpoint redox potential of cytochrome c" was measured over the pH range 4-10. The pH dependence of the midpoint redox potential was interpreted in terms of a model that considers the redox-state dependence of the ionization of two distinct and non-interacting protonated groups in the protein. This analysis led to the following pKa values within the pH range studied: pKa10 = 6.4, pKa1r = 5.4 and pKa2r = 8.1. Proton-NMR spectroscopy was used to assist the characterization of the two ionizing groups responsible for the observed redox-Bohr effect: the group ionizing with a lower pKar was assigned to a haem propionic acid substituent and the other to the axial histidine ligand which becomes detached upon reduction, which has a pKa0 too low to be measured. It is shown that M. methylotrophus cytochrome c" is able to couple electron and proton transfer in the physiological pH range through a mechanism involving reversible change in the haem-iron coordination. Possible implications for the physiological role of the protein are discussed.