Determination of carotenoids, total phenolic content, and antioxidant activity of Arazá (Eugenia stipitata McVaugh), an Amazonian fruit

The fruit of Arazá (Eugenia stipitata McVaugh) native to the Colombian Amazon is considered a potentially economically valuable fruit for the Andean economy due to its novel and unique taste. The fruit has an intense yellow color, but its chemical composition and properties have not been well studied. Here we report the identification and quantitation of carotenoids in the ripe fruit using high performance liquid chromatography (HPLC) with photodiode array detector (PDA) and atmospheric pressure chemical ionization (APcI) mass spectrometry (MS/MS). The qualitative carotenoid profile of the fruit according to maturity stage was also observed. Furthermore, antioxidant activity of the peel and pulp were assessed using the ferric reducing ability of plasma (FRAP), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and 1,1-diphenyl-2-picrylhydrazyl (DPPH) methods, in addition to chemical indexes and total phenolic content. Multiple carotenoids were identified in the peel and pulp including four xanthophylls (free and esterified as their mono and diesters) and two carotenes. One of the xanthophylls was tentatively identified as zeinoxanthin, while the others were identified as lutein, zeaxanthin, and β-cryptoxanthin. Carotenes included α-carotene and β-carotene. The total carotenoid content was significantly higher in the peel (2484 ± 421 μg/100 g FW) than in the pulp (806 ± 348 μg/100 g FW) with lutein, β-cryptoxanthin, and zeinoxanthin as the major carotenoid components. The unique carotenoid composition of this fruit can differentiate it from other carotenoid-rich fruits and perhaps be useful in authentication procedures. Overall, results from this study suggest that Colombian Arazá may be a good edible source of carotenoids important in retinal health as well as carotenoids with provitamin A activity. Therefore, Arazá fruit can be used as a nutraceutical ingredient and in production of functional foods in the Colombian diet.     

Phosphorus forms and enzymatic hydrolyzability of organic phosphorus in soils after 30 years of organic and conventional farming

Lower P‐input levels in organic than conventional farming can decrease soil total and available P, which can potentially be resupplied from soil organic P. We studied the effect of 30 y of conventional and organic farming on soil P forms, focussing especially on organic P. Soil samples (0–20 cm) were taken in a field experiment with a nonfertilized control, two organic systems receiving P inputs as animal manure, and two conventional systems receiving only mineral P or mineral P and manure. Soils were analyzed for total, inorganic, organic, and microbial P, by sequential P fractionation and by enzyme additions to alkaline soil extracts. Samples taken prior to starting the experiment were also analyzed. Average annual P balances ranged from –20 to +5 kg ha^–1. For systems with a negative balance, labile and moderately labile inorganic P fractions decreased, while organic and stable inorganic P fractions were hardly affected. Similar quantities and proportions of organic P extracted with NaOH‐EDTA were hydrolyzed in all soils after addition of an acid phosphatase, a nuclease, and a phytase, and enzyme‐stable organic P was also similar among soils. Thus, neither sequential fractionation nor enzyme addition to alkaline soil extracts showed an effect of the type of applied P (manure vs. mineral) on organic P, suggesting that organic P from manure has largely been mineralized. Thus far, we have no indication that the greater microbial activity of the organic systems resulted in a use of stable P forms.     

Molecular markers and allelic relationships of anthracnose resistance gene cluster B4 in common bean

Angular leaf spot is one of the major diseases of the common bean. The extensive genetic variability of this pathogen requires the constant development of new resistant cultivars. Different sources of resistance have been identified and characterized. For the State of Minas Gerais, Brazil, four main resistance sources were found: Mexico 54, AND 277, MAR 2 and Cornell 49-242. Independent characterization of these genotypes demonstrates that resistance in all four sources is dominant and monogenic. However, there are no studies on the relationship and independence of these genes. In the present work, allelism tests were carried out to understand the relationship among the resistance genes present in these four resistance sources. The data revealed a much higher complexity in the resistance inheritance of these genes than previously reported. It was demonstrated that Cornell 49-242 possesses a dominant gene (Phg-3); Mexico 54 possesses three genes, denominated Phg-2, Phg-5 and Phg-6. In MAR 2, two genes were found, one independent designated Phg-4 and the other, an allelic form of Phg-5, denominated of Phg-5². Allelic forms were also found in AND 277, Phg-2², Phg-3² and Phg-4². These results have special importance for breeding programs aiming to pyramid resistance genes.     

Relationships between microbial indices in roots and silt loam soils forming a gradient in soil organic matter

Perennial rye grass (Lolium perenne) was grown in a greenhouse pot experiment on seven soils to answer the question whether the microbial colonisation of roots is related to existing differences in soil microbial indices. The soils were similar in texture, but differed considerably in soil organic matter, microbial biomass, and microbial community structure. Ergosterol and fungal glucosamine were significantly interrelated in the root material. This ergosterol was also significantly correlated with the average ergosterol content of bulk and rhizosphere soil. In addition, the sum of fungal C and bacterial C in the root material revealed a significant linear relationship with microbial biomass C in soil. The colonisation of roots with microorganisms increased apparently with an increase in soil microbial biomass. In the root material, microbial tissue consisted of 77% fungi and 23% bacteria. In soil, the fungal dominance was slightly, but significantly lower, with 70% fungi and 30% bacteria. Fungal glucosamine in the root material was significantly correlated with that in soil (r=0.65). This indicates a close relationship between the composition of dead microbial remains in soil and the living fraction in soil and root material for unknown reasons.     

Copper binding capacity of root exudates of cultivated plants and associated weeds

Cu binding to root exudates of two cultivated plants, wheat (Triticum aestivum) and rape (Brassica napus), and two weeds associated with wheat, dog daisy (Matricaria inodora) and cornflower (Centaurea cyanus), was studied in vitro under hydroponic and sterile conditions. Nutrient solutions were prepared with or without P. A MetPLATE microbiological test was used to assess the metal complexing capacity of root exudates. In the P-deficient solutions, no exudation was observed for any of the four plants; consequently, no Cu binding occurred. When P was present in the nutrient solutions, the plant exudates displayed differing abilities to complex Cu. No difference was detected in the binding capacity of the dog daisy or cornflower, and the blank [heavy metal binding capacity (HMBC)=1.07, 1.40 and 1.00, respectively]; however, the rape and wheat exudates were found to complex Cu in rhizospheric solutions (HMBC=1.73 and 3.00, respectively). The concentrations of exuded organic C were 1.2, 10.8, 15.3 and 15.7 mg l^-1 for the dog daisy, cornflower, wheat and rape, respectively. These results suggest that the nature, as well as the amount, of the organic compounds exuded by plant root, is important in determining the extent of Cu complexation.     

Die Rolle der mikrobiellen Biomasse und des mineralisch fixierten Ammoniums bei den Stickstoff-Transformationen in niedersächsischen Löß-Ackerböden unter Winter-Weizen. II. Umsetzung von 15N-markiertem Stickstoff

Significance of microbial biomass and mineral fixed ammonium with respect to the nitrogen transformations in loess soils of Niedersachsen during the growing season of winter wheat. II. ¹⁵N-turnover Field experiments 1988/89 on a fallow plot of the southern Niedersachsen loess area with straw application (δ 10 t · ha^?1, homogeneously incorporated by hand) yielded an increase in microbial biomass-N (N_mic) by 60 kg N · ha^?1 · 30 cm^?1 until March 1989 and further 40 kg N · ha^?1, till May which was almost completely remobilized until harvest. For a cropped plot (with winter wheat and 10 t · ha^?1 straw incorporation), N immobilization was of similar magnitude. Up to 18% of the applied ¹⁵N-fertilizer (185 kgN · ha^?1) were microbially immobilized. In contrast to 1988/89, no significant mass change of N_mic occurred in 1991 due to straw application (δ 10t · ha^?1). Variations in the amount of N_mic were nearly independent on the treatment (crop, with 140 kg fertilizer-N · ha^?1 or without N-fertilizer, respectively; fallow plot without fertilizer-N) within a range of 225-400 kg N · ha^?1 · 30 cm^?1. Directly after N-application (each 70 kg N · ha^?1 in March and in May), up to 100% of the fertilizer-N were assimilated by the microbes. Subsequently, remobilization of the immobilized nitrogen occurred within 2 (in March) or 6 weeks (in May), respectively. Simultaneously, organic soil-N was mineralized after each N-application and minerally fixed for us biggest part. Between March and June, the fixed NH₄+ decreased by about 112 kg · ha^?1 · 30 cm^?1.     

Analysis of early lipid oxidation in smoked, comminuted pork or poultry sausages with spices

Dynamic headspace/gas chromatography-mass spectrometry (GC-MS), front-face fluorescence spectroscopy, and a gas-sensor array technique (electronic nose) have previously detected lipid oxidation in pork back fat or mechanically recovered poultry meat earlier than or at the same time as a sensory panel. The present study was focused on measurement of early lipid oxidation in a more complicated product (freeze-stored, smoked sausages with spices). During the storage time, formation of components contributing to rancid odor and flavor (e.g., hexanal and 1-penten-3-ol) could be monitored with dynamic headspace/GC-MS. The GC-MS data also showed a decrease in 2-furancarboxaldehyde, which could indicate loss of Maillard type components often associated with acidic or meat odor and flavor. The fluorescence spectra were difficult to interpret, probably due to the simultaneous influence from increasing levels of lipid oxidation products and loss of fluorescent Maillard or spice components. The gas-sensor array responses were dominated by signals from, e.g., spice and smoke compounds.     

Analysis of the early stages of lipid oxidation in freeze-stored pork back fat and mechanically recovered poultry meat

An analytical method that can detect low levels of oxidation in food earlier than a sensory panel would be a valuable tool for food manufacturers as well as research institutes. Two model matrixes, pork back fat and mechanically recovered poultry meat (MRPM), were freeze-stored in air at -20 degrees C for 26 weeks. Peroxide value, thiobarbituric acid reactive substances, volatiles analyzed with dynamic headspace gas chromatography-mass spectrometry (GC-MS) and a gas-sensor array technique (electronic nose), chemiluminescence, and front-face fluorescence were evaluated against sensory analysis with regard to detection of early oxidation and correlation with sensory data. Fluorescence and GC-MS could detect oxidative changes in pork back fat earlier than the sensory panel and the electronic nose at the same time. The three methods were highly correlated with sensory attributes (r = 0.8-0.9). GC-MS gave the best results with regard to detection of small oxidative changes in MRPM.     

Prevalence of specific IgG-antibodies against Toxoplasma gondii in domestic turkeys determined by kinetic ELISA based on recombinant GRA7 and GRA8

The protozoan parasite Toxoplasma (T.) gondii is one of the most common zoonotic infectious agents worldwide. Besides its sexual reproduction in cats, T. gondii can also infect a wide spectrum of other warm-blooded animals. These include animals used for human consumption such as pigs or chickens. Nevertheless, the role of turkeys for the epidemiology of T. gondii infections has not been studied thoroughly. We have established a kinetic ELISA (KELA) for the detection of T. gondii-specific IgG antibodies in turkey serum samples. The test is based on the recombinant dense granule antigens GRA7 and GRA8. These proteins were used as an antigen mixture at a concentration of 0.13 μg per well. The overall sensitivity of the assay was between 92.6% and 100% and the specificity ranged from 78.1% to 100%, depending on the method used to calculate these parameters. Using this KELA we examined 1913 turkey serum samples from 14 turkey farms from different areas of Germany. From these sera, 387 produced a signal in the KELA, corresponding to a true seroprevalence of up to 20.2%. The seropositivity rate in individual fattening cycles at individual farms ranged from 0.0% to 77.1%, whereas the rates were highly variable within the individual farms and individual fattening cycles. Consequently, conditions of animal husbandry could not be associated with particular seroprevalence rates. Although seropositivity cannot be linked directly to infectious tissue cysts in the muscle tissue of commercially produced turkey meat, we state that there is a potential risk of being infected by consuming turkey meat products that were not heat treated.