Ion chromatographic determination of chloride in mustard sauces.     

E López Agüero  N Bosch Bosch  C Barrera Vázquez  B López Ruiz 《Journal of agricultural and food chemistry》1999,47(11):4682-4685

A new, simple, precise, and rapid ion chromatography (IC) method has been developed to determine chloride in mustard sauces using a mixture of phthalic acid, acetone, and water adjusted to pH 5.0 as eluent. Conductometric detection was carried out. The retention time for chloride was 1.5 min. Linearity was obtained up to a concentration level of 100 mg/L NaCl. The method was statistically evaluated for accuracy and precision after being used to assay the chloride from mustard sauces. Within the same samples, the chloride levels obtained by IC were compared with the sodium concentrations quantified by atomic absorption spectrophotometry.  相似文献   

Recovery of cover-crop-N in the soil-plant system in the Guinea savannah zone of Ghana     

Mathias?FosuEmail author  Ronald?F.?Kühne  Paul?L.?G.?Vlek 《Biology and Fertility of Soils》2003,39(2):117-122

In order to understand the efficiency of residue-N use and to estimate the minimum input required to obtain a reasonable level of crop response, it is important to quantify the fate of the applied organic-N. The recovery of N from ¹⁵N-labelled Crotalaria juncea was followed in the soil and the succeeding maize crop. Apparent N recovery (ANR) by maize from unlabelled Crotalaria juncea, Crotalaria retusa, Calopogonium mucunoides, Mucuna pruriens and mineral fertilizer at three locations were also evaluated. The maize crop recovered 4.7% and 7.3% of the ¹⁵N-labelled C. juncea-N at 42 days after sowing (DAS) and at final harvest, respectively. The corresponding ¹⁵N recovery from the soil was 92.4% and 58.5%. The highest mean ANR of 57.4% was with mineral fertilizer, whereas the mean ANR of 14.3% from C. retusa was the lowest. A large pool substitution and added-N interaction effect was observed when comparing N recovery from the labelled and unlabelled C. juncea. The amount of residue-N accounted for by the isotope dilution method at 42 DAS was 97.1% and at final harvest 65.8%. The large residue-N recovery in the soil organic-N pool explains the residual effect usually observed with organic residue application.  相似文献   

Volatile flavor components of stored nonfat dry milk.   总被引：1，自引：0，他引：1  

Yonca Karagül-Yüceer  Keith R Cadwallader  MaryAnne Drake 《Journal of agricultural and food chemistry》2002,50(2):305-312

Nonfat dry milk (NDM) is widely used both as an ingredient in other preparations and for direct consumption. Flavor quality of NDM is a critical parameter because it can directly impact final product quality. Flavors can be formed in NDM during subsequent storage. Identification of compounds responsible for storage-induced flavors is necessary to correlate sensory quality with potential sources of the flavors. Six NDM samples were selected for volatile flavor analysis based on sensory analysis and storage time. Volatile components were extracted by direct solvent extraction/high vacuum distillation. Volatile extracts were separated into neutral/basic and acidic fractions and analyzed by gas chromatography-olfactometry (GCO) and aroma extract dilution analysis (AEDA). A variety of aldehydes, ketones, and free fatty acids were responsible for generation of flavors in stored NDM. The following compounds exhibited high aroma impact by AEDA: 3-(methylthio)propanal (boiled potato); o-aminoacetophenone (corn tortilla); 2,5-dimethyl-4-hydroxy-3(2H)-furanone and 2-methyl-3-hydroxy-4H-pyran-4-one (burnt sugar); butanoic acid (cheesy); pentanoic acid (sweaty); acetic and hexanoic acids (sour/vinegar); octanoic, decanoic, and dodecanoic acids (waxy); p-cresol (cowy/barny); 3-methylindole (fecal); dimethyl trisulfide (cabbage); (E,E)-2,4-decadienal (fried/fatty); furfuryl alcohol (rubber/vitamin); phenylacetic acid (rose-like); and 1-octen-3-one (mushroom).  相似文献   

Use of nootkatone as a senescence indicator for Rouge La Toma Cv. grapefruit (Citrus paradisi Macf.)     

Biolatto A  Sancho AM  Cantet RJ  Güemes DR  Pensel NA 《Journal of agricultural and food chemistry》2002,50(17):4816-4819

The objective of this research was to study the usefulness of nootkatone as a senescence indicator for Rouge La Toma cv. grapefruit (Citrus paradisi Macf.), simulating different treatments that included the normal postharvest handling of citrus fruits: temperature conditioning, cold storage, shipment periods to overseas markets such as Japan and the U.S., marketing conditions, and storage at nonchilling temperature (control treatments). The highest nootkatone levels, determined by GLC-MS analyses, were detected in fruits subjected to control treatments. No significant differences were observed in nootkatone levels between treatments either with or without temperature conditioning prior to the start of the cold storage. Levels of nootkatone increased throughout time for all assayed treatments. The linear regressions of nootkatone levels showed correlation coefficients of 0.80 and 0.83 with storage time (29 and 42 days, respectively). Therefore, nootkatone appears to be a good indicator of senescence for Rouge La Toma grapefruit.  相似文献   

Aroma-active components of nonfat dry milk.     

Y Karagül-Yüceer  M A Drake  K R Cadwallader 《Journal of agricultural and food chemistry》2001,49(6):2948-2953

Application of aroma extract dilution analysis (AEDA) on the volatile components of low-, medium-, and high-heat-treated nonfat dry milks (NDM) revealed aroma-active compounds in the log(3) flavor dilution (log(3) FD) factor range of 1 to 6. The following compounds contributed the highest log(3) FD factors to overall NDM flavor: 2,5-dimethyl-4-hydroxy-3(2H)-furanone [(Furaneol), burnt sugar-like]; butanoic acid (rancid); 3-(methylthio)propanal [(methional), boiled potato-like]; o-aminoacetophenone (grape-like); delta-decalactone (sweet); (E)-4,5-epoxy-(E)-2-decenal (metallic); pentanoic acid (sweaty); 4,5-dimethyl-3-hydroxy-2(5H)-furanone [(sotolon), curry]; 3-methoxy-4-hydroxybenzaldehyde [(vanillin), vanilla]; 2-acetyl-1-pyrroline and 2-acetyl-2-thiazoline (popcorn-like); hexanoic acid (vinegar-like); phenylacetic acid (rose-like); octanoic acid (waxy); nonanal (fatty); and 1-octen-3-one (mushroom-like). The odor intensities of Furaneol, butanoic acid, methional, o-aminoacetophenone, sotolon, vanillin, (E)-4,5-epoxy-(E)-2-decenal, and phenylacetic acid were higher in high-heat-treated samples than others. However, the odor intensities of lactones, 2-acetyl-1-pyrroline, and 2-acetyl-2-thiazoline were not affected by heat treatment. Sensory evaluation results also revealed that heat-generated flavors have a major impact on the flavor profile of NDM.  相似文献   

Optimization of a pilot-scale process for producing lupin protein isolates with valuable technological properties and minimum thermal damage     

D'Agostina A  Antonioni C  Resta D  Arnoldi A  Bez J  Knauf U  Wäsche A 《Journal of agricultural and food chemistry》2006,54(1):92-98

This paper describes a pilot process for obtaining protein isolates from white lupin seed with improved water solubility and technofunctional properties as well as reduced thermal damage. After a careful optimization of the process parameters, two valuable food ingredients were prepared: lupin protein isolate type E, with a useful emulsifying capacity, and lupin protein isolate type F, with a high capability of foam formation and stabilization. The spray-drying process was particularly critical for inducing some thermal damage, but a careful selection of the conditions permitted ingredients having only marginally impaired lysine bioavailability to be obtained. The reproducibility of the protein extraction process was tested on two different lupin varieties.  相似文献   

Occurrence of Polycyclic Musks in Sewage Sludge and their Behaviour in Soils and Plants. Part 1: Behaviour of Polycyclic Musks in Sewage Sludge of Different Treatment Plants in Summer and Winter (5 pp)     

Josef Müller  Walter Böhmer 《Journal of Soils and Sediments》2006,6(4):231-235

Background, Aim and Scope   Part 1: Behaviour of Polycyclic Musks in Sewage Sludge of Different Treatment Plants in Summer and Winter Part 2: Investigation of Polycyclic Musks in Soils and Plants -  Preamble. In Part 1 of the study, screening tests were performed to investigate the occurrence of PCMs in sewage sludges. For a preliminary risk assessment, further information is needed about their behaviour in the terrestrial environment. Hence, Part 2 examined the adsorption of PCMs to soil, their dissipation and leaching in soil and their uptake by plants. Background, Aim and Scope   Polycyclic Musks (PCMs) enter the environment via the waste water system. Because of their persistence, they can accumulate in different matrices like sewage sludge or biota. By the use of sewage sludge as a fertilizer, PCMs are transferred to agricultural soils. Therefore, in Part 1 of the study, screening tests were performed to investigate the occurrence of PCMs in sewage sludge. For a preliminary risk assessment, further information is needed about their behaviour in the terrestrial environment. Hence, Part 2 of the study examined the adsorption of PCMs to soil, their dissipation and leaching in soil, and their uptake by plants. Materials and Methods: In the screening study, samples of activated sewage sludge were taken both in summer and in winter at 21 treatment plants. In order to get an overview of the contamination situation, sampling covered different types of treatment plants (in rural, urban, industrial areas). Analytical methods for the determination of HHCB, AHTN, ADBI, ATTN, AHDI and ATII in the sludge samples were developed and applied. Results: The analytical screening of PCMs showed their presence in activated and dried sewage sludge samples. HHCB and AHTN represented about 95% of the PCMs investigated. Their concentrations in the activated sludge samples varied between 2.9 and 10.4 mg/kg dry mass (dm) and 1.1 to 4.2 mg/kg dm, respectively. Although different types of sewage treatment plants were investigated, similar PCM levels were found, showing the widespread input of these compounds into domestic waste water. Discussion: PCM concentrations in activated sludge varied widely. The variation drops substantially when concentrations are related to the varying dry mass. In dehydrated sludge, PCM concentrations were up to 24 mg/kg dm for HHCB and up to 6.9 mg/kg dm for AHTN. These high values are comparable to those obtained in other investigations analysing PCMs. If the degradation of organic mass during anaerobic decomposition is included in the evaluation, the figures obtained are comparable to those for activated sludge. Elimination in sewage sludge was higher in summer than in winter. Therefore, the contamination of the sludges in winter reached higher levels compared to the summer. Conclusions: The results show that PCMs are widespread contaminants in sewage sludge. Recommendations and Perspectives: PCM should be considered in a risk assessment as potential contaminants of sewage sludge destined for agricultural use. Due to the high PCM levels in sewage sludge, further investigations into the degradation and elimination behaviour in sewage sludge have to be carried out, including that involving PCM metabolites such as lactone derivatives.  相似文献   

Effects of rhodium heterogeneous catalyst and isomerization conditions on linoleic acid conjugation of soybean oil     

Pakdeechanuan P  Intarapichet KO  Fernando LN  Grün IU 《Journal of agricultural and food chemistry》2005,53(4):923-927

Rhodium heterogeneous catalyst was used to catalyze isomerization of linoleic acid in soybean oil to conjugated linoleic acid (CLA). A central composite rotatable design with five levels of three variables, namely, reaction temperature, stirring speed, and reaction time, was used to determine the maximum CLA yield. The formation of CLA during isomerization was greatly dependent on the reaction temperature and time. The CLA content of soybean oil increased from 0.63 to 202.42 mg/g oil when isomerization was done at 200 degrees C, with a stirring speed of 200 rpm for 49 min. Analysis of triacylglycerol positions showed that linoleic acid at any position in a triacylglyceride could possibly be isomerized to CLA.  相似文献   

Influence of storage practices on acrylamide formation during potato frying     

De Wilde T  De Meulenaer B  Mestdagh F  Govaert Y  Vandeburie S  Ooghe W  Fraselle S  Demeulemeester K  Van Peteghem C  Calus A  Degroodt JM  Verhé R 《Journal of agricultural and food chemistry》2005,53(16):6550-6557

A number of parameters linked to storage of potatoes were evaluated with regard to their potential to influence the acrylamide formation in French fries. Acrylamide, which is a potential human carcinogen, is reported to be formed during the frying of potatoes as a result of the reactions between asparagine and reducing sugars. This study was conducted using three potato varieties (Bintje, Ramos, and Saturna) typically used in Belgium, The Netherlands, and the northern part of France for French fry and crisp production. Saturna, mainly used in crisp production, appeared to be the least susceptible for acrylamide formation during frying. Especially storage at low temperatures (4 degrees C) compared to storage at 8 degrees C seemed to enhance acrylamide formation due to a strong increase in reducing sugars caused by low-temperature storage. Because of the reversible nature of this physiological reaction, it was possible to achieve a significant reduction of the reducing sugars after a reconditioning of the cold-stored potatoes for 3 weeks at 15 degrees C. All changes in acrylamide concentrations could mainly be explained by the reducing sugar content of the potato (R2 = 0.84, n = 160). This means that, by ensuring a low reducing sugar content of the potato tuber, the risk for acrylamide formation will largely be reduced. Finally the use of a sprout inhibitor did not influence the composition of the potato, and thus acrylamide formation was not susceptible to this treatment.  相似文献   

Investigations on the Behaviour of Fenpropimorph and its Metabolite Fenpropimorphic Acid in Soils     

Matthias Stockmaier  Robert Kreuzig  Müfit Bahadir 《Pest management science》1996,46(4):361-367

The fate of fenpropimorph and its metabolite fenpropimorphic acid was investigated in a silty sand soil and in a clayey silt soil. In laboratory and field experiments fenpropimorph disappeared without a lag phase. A few days after application fenpropimorphic acid was detected. Additional laboratory experiments with [¹⁴C]fenpropimorph emphasized the significance of mineralization and the formation of non-extractable residues. The determination of soil/water distribution coefficients of parent compound and metabolite yielded a higher leaching potential for fenpropimorphic acid due to its higher polarity. This was confirmed by performing a laboratory column test under worst-case conditions. Under field conditions, however, fenpropimorphic acid was detected only in the superficial soil layers (0–5 cm) of both investigation sites at very low concentrations.  相似文献