Effect of sample preparation on the measurement of sugars, organic acids, and polyphenols in apple fruit by mid-infrared spectroscopy

The objectives of this study were (i) to test different conditions of freezing, thawing, and grinding during sample preparation and (ii) to evaluate the possibility of using mid-infrared spectroscopy for analyzing the composition of sugars, organic acids, and polyphenols in apples. Seven commercial apple cultivars were chosen for their large variability in composition (total polyphenols from 406 to 1033 mg kg(-1) fresh weight). The different conditions of sample preparation affected only the phenolic compounds and not sugars or organic acids. The regression models of the mid-infrared spectra showed a good ability to estimate sugar and organic acid contents (R(2) ≥ 0.96), except for citric acid. Good predictions were obtained for total phenolic, flavan-3-ols, and procyanidins (R(2) ≥ 0.94) provided oxidation was avoided during sample preparation. A rapid and simple procedure was then proposed for phenolic compounds using sodium fluoride during sample homogenization at ambient temperature and freeze-drying before spectra acquisition.     

Changes in the contents of sugars and organic acids during the ripening and storage of sufu, a traditional Oriental fermented product of soybean cubes

In the present study, sufu, an oriental fermented product of soybeans, was prepared by ripening the tofu cubes in Aspergillus oryzae fermented rice-soybean koji mash for 16 days at 37 °C. The sufu product was further kept at room temperature for another 30 days. Examining the changes in the sugar content revealed that stachyose, raffinose, and sucrose contents of tofu and rice-soybean koji granules decreased while levels of glucose and fructose increased during the ripening period and after storage. Glucose was the most abundant sugar detected. Four organic acids, including oxalic, lactic, acetic, and citric acid, were detected in the sufu product and koji granules after ripening. Generally, the contents of these organic acid increased as the ripening period was extended. Among them, acetic acid was the most highly detected.     

Changes in inorganic and organic solutes in citrus growing under saline stresses

Salinity is a key factor limiting cirrus production in many world areas. The two citrus genotypes sour orange (Citrus aurantium L) and macrophylla (Citrus macrophylla Wester), that differ in their ability to restrict sodium (Na) and chloride (Cl) transport to the shoot under salt stress, were studied to compare the contribution of both inorganic and organic solutes in osmotic adjustment. Plants of both citrus genotypes were grown in isosmotic (0.23 MPa) solutions of different ionic composition (Na, NaCl, Cl, and concentrated macronutrients), and leaf and root solutes were measured to determine their relative contribution to osmotic adjustment. Both leaf water and osmotic potentials decreased in response to imposed stress in the nutrient media, regardless of the isosmotic treatment. Growth reduction was more severe in macrophylla than in sour orange, except for macronutrient treatment. The major components associated with the osmotic adjustment were inorganic solutes (ranging from 65 to 85% of total solutes) and organic solutes (ranging from 15 to 35%, depending on the genotype and the isosmotic treatment). Among these, carbohydrates were the major organic components (6–24%), with glucose the main osmoregulating sugar in Cl‐containing treatments. The contribution of the organic acids and amino acids to the osmotic adjustment of plant under saline stress seemed to be less important in these citrus species.     

Composition of amino acids,organic acids,and sugars in the peribacteroid space of soybean root nodules

In leguminous root nodules, bacteroids are differentiated from rhizobia and are surrounded by a peribacteroid membrane (PBM) forming an intracellular structure designated as symbiosome. Through the peribacteroid space (PBS) between the PBM and bacteroids, metabolic substances and signal compounds are exchanged between two symbionts. In this study, organic compounds with low molecular weight in the PBS were collected from isolated symbiosomes of soybean (Glycine max L.) root nodules, and their composition was analyzed and compared with that of the organic compounds in whole root nodules and bacteroids. Major differences were detected in the molar percentages of amino and organic acids, and sugars, to the total low molecular weight organic compounds among whole root nodules, PBS, and bacteroids. The PBS composition was characterized by abundant sugars and poor amino acids. Also the composition of the amino acids, organic acids, and sugars in the PBS was clearly different from that in whole root nodules and bacteroids. The PBS sugar composition was characterized by the predominance of inositols, especially myo-inositol at the 5th and 7th weeks of the host plant growth stages. Changes in the myo- and D-chiro- inositol balance at the host plant growth stages occurred and a syntony was observed between the PBS and bacteroids. The localization of myo-inositol in the PBS accounted for almost 70% of the total myo-inositol in root nodules. A small difference in the PBS composition between two soybean cultivars was recorded but it varied with the growth stages. It was tentatively concluded that the PBS sugar composition affected the bacteroidal sugar composition in soybean plants, and that inositol utilization in the bacteroids could be a factor controlling the bacteroidal function level which varied with the host plant growth stages.     

Assessment of relative sensitivities during early growth stages of selected crop species subjected to simulated acidic rain

Under greenhouse conditions, experiments were performed to assess the cultivar sensitivity (during early growth stages) to simulated acidic rain treatments of six economically important crop species. The accumulation of dry biomass was investigated for the following crops: alfalfa, barley, cabbage, corn, cucumber, and soybean. For each crop, treatments consisted of eight acidity levels in simulated rain — pH 2.6, 3.0, 3.4, 3.8, 4.2, 4.6, 5.0, and 5.6. Crops varied in response to increased rain acidity. Overall, exposure of cultivars to a range of acidities in simulated rain had very little effect on the dry biomass accumulation of shoot and root components. With the exception of cabbage, the crop species examined were highly resistant to injury and dry biomass reduction after exposure to acidic rainfall. The results also demonstrated that plant response to simulated acid rain was not only species dependent, but also cultivar dependent.     

Soil moisture levels affect mycorrhization during early stages of development of agroforestry plants

Plants respond differentially to different arbuscular mycorrhizal fungi (AMF) as well as to the different soil moisture levels. Based on this background, the present study was carried out to investigate the effects of different levels of soil moisture and AMF inoculations on mycorrhization and growth of important agroforestry plants, viz., Phaseolus mungo, Triticum aestivum, Eucalyptus tereticornis, and Albizia procera. The experiments consisted of main treatment, i.e., three levels of soil moisture [field capacity (FC?=?16 %), half-field capacity (FC/2?=?8 %) and double-field capacity (2×FC?=?32 %)] and four subtreatments (mycorrhizal inoculations), viz., Acaulospora scrobiculata, Glomus cerebriforme, Glomus intraradices, and un-inoculated (control). AMF inoculations significantly (P?<?0.05) increased growth and P uptake, in all tested plant species. In P. mungo, maximum AMF efficiency was observed at FC while in other plants, AMF were equally effective at FC/2 and 2×FC. Different inoculants were effective at different moisture levels. Furthermore, mycorrhization was the highest at FC. AMF inoculations were more important than soil moisture (explaining 33–97 % variation in growth) in P. mungo, T. aestivum, and A. procera (forward selection method), whereas soil moisture was more important for growth of E. tereticornis. Thus, it may be stated that depending upon soil moisture, inoculation of plants with suitable AMF consortium can be beneficial.     

Priming effects of sugars,amino acids,organic acids and catechol on the mineralization of lignin and peat

The ¹⁴C‐labeled substrates glucose, fructose, alanine, glycine, oxalic acid, acetic acid, and catechol were incubated at 20 °C in a model system that consisted of sand mixed with lignin or peat (3 % C_org). Each substrate was added at either 80 or 400 μg C (g sand)^—1. During 26 days of incubation with an inoculum extracted from forest soil, the amount of CO₂ evolved was measured hourly. The amount of ¹⁴CO₂ was determined after 4, 6, 12, 19, and 26 days. After 26 days of incubation, each substrate showed priming effects, but not in all examined treatments. Most substrates stimulated the degradation of the model substances (positive priming effects). Negative priming effects only were found in the lignin system with oxalic acid and catechol addition at both concentrations. The strongest positive priming occurred in the peat system with the oxalic acid addition of 80 μg C g^—1 where 1.8 % of the peat were mineralized after 26 days, compared to 0.7 % in the control. The addition of 400 μg alanine‐C g^—1 caused the strongest increase in lignin mineralization, amounting to 3.9 % compared to 2.8 % in the control. During the incubation the extent of priming changed with time. Most substrates caused the strongest effects during the first 4 to 10 days of incubation. The extent of priming depended on substrate type, substrate concentration, and organic model substance. Possibly this is due to the activation of different microorganisms.     

Changes in sugars,acids, and volatiles during ripening of koubo [Cereus peruvianus (L.) Miller] fruits

The columnar cactus Cereus peruvianus (L.) Miller, Cactaceae (koubo), is grown commercially in Israel. The unripe fruits are green, and the color changes to violet and then to red when the fruit is fully ripe. The content of soluble sugars was found to increase 5-fold during ripening. Glucose and fructose were the main sugars accumulated in the fruit pulp, and each increased from 0.5 to 5.5 g/100 g fresh weight during ripening. The polysaccharides content decreased during ripening from 1.4 to 0.4 g/100 g fresh weight. The titratable acidity decreased and the pH increased during ripening. The major organic acid found in the fruit was malic acid, which decreased from 0.75 g/100 g fresh weight at the mature green stage to 0.355 g/100 g fresh weight in ripe fruits. Citric, succinic, and oxalic acids were found in concentrations lower than 0.07 g/100 g fresh weight. Prominent accumulation of aroma volatiles occurred toward the end of the ripening process. The main volatile found in the ripe fruit was linalool, reaching concentrations of 1.5-3.5 microg/g fresh weight.     

Changes in chloroplast pigments of olive varieties during fruit ripening

Changes in chlorophyll and carotenoid pigments of five olive (Olea europaea L.) varieties destined for milling were investigated at six consecutive ripening stages. There was a manifest dependence between olive variety, moment of picking, and chloroplast pigment composition of the fruits. Although the content of chlorophylls and carotenoids differed with fruit variety, ripening always involved their gradual loss, which becames more pronounced with increased presence of anthocyanin compounds. The relative rates of disappearance of chlorophylls and carotenoids were markedly different between varieties, implying that the catabolism of these pigments takes place at a relative rate inherent to each variety. The varieties less rich in pigments showed the most extreme behavior. The highest relative rate of disappearance was observed in fruits of the Blanqueta variety, and the lowest was observed in those of Arbequina. The chlorophyll a/chlorophyll b ratio remained practically constant during ripening, with a value very similar for Hojiblanca, Picual, Cornicabra, and Blanqueta, but much higher for Arbequina, implying that the structure of the photosynthetic apparatus is different in the latter variety. In the five varieties studied, lutein was the slowest carotenoid to be degraded, so that its percentage in the fruits increased with ripening, whereas beta-carotene was the fastest to disappear. In ripe fruits covered with anthocyanins, chloroplast pigments were retained in both skin and pulp, with the rate of disappearance being much higher in the latter.     

Gas chromatographic determination of fenpropimorph residues in citrus fruit

A rapid gas chromatographic method for determining fenpropimorph residues in citrus fruit is reported. The fungicide is extracted with hexane after pH adjustment of the fruit homogenate. A short liquid-liquid partitioning process is performed before gas chromatography on an OV-17 column with nitrogen-phosphorus specific detection. The limit of detection of the method was 0.01 mg/kg, based on a 25 g sample. Recovery was always higher than 70%. Fenpropimorph residues in "Washington Navel" oranges and "Hernandina" clementine fruits dipped in a 1500 mg/L fungicide solution were determined. The fungicide remains mainly in the peel, with levels less than 0.1 mg/kg in the pulp. Fungicide residues in the peel decrease during storage, mainly in Washington Navel peel, where values decreased from 5.2 to 2.8 mg/kg.     

Determination of organic acids, sugars, diacetyl, and acetoin in cheese by high-performance liquid chromatography.

Sugars (lactose, glucose, and galactose), nonvolatile acids (citric, orotic, piruvic, lactic, ossalic, and hippuric), some free fatty acids (formic, acetic, propionic, butyric, isobutyric, valeric, and isovaleric), diacetyl, and acetoin were separated on an Aminex HPX-87H column using a simple isocratic HPLC method and identified by retention times with ultraviolet and refractive index detectors. With the proposed technique it is possible to evaluate the development of microbial fermentations and, at the same time, degree of cheese ripening.     

Changes in virgin olive oil quality during low-temperature fruit storage

'Frantoio' olive fruits were stored at low temperature (4 +/- 2 degrees C) for 3 weeks to investigate the effect of postharvest fruit storage on virgin olive oil quality. Volatile compounds and phenolic compounds explained the changes in sensory quality that could not be explained with quality indices (FFA, PV, K232, and K270). Increases in concentrations of ( E)-2-hexenal and hexanal corresponded to positive sensory quality, whereas increases in ( E)-2-hexenol and (+)-acetoxypinoresinol were associated with negative sensory quality. Volatile and phenolic compounds were also indicative of the period of low-temperature fruit storage. Oleuropein and ligstroside derivatives in olive oil decreased with respect to storage time, and their significant ( p < 0.05) change corresponded to changes in bitterness and pungency. ( Z)-2-Penten-1-ol increased during low-temperature fruit storage, whereas 2-pentylfuran decreased. Changes in volatile compounds, phenolic compounds, quality indices, and sensory notes indicated that virgin olive oil quality was lost within the first week of low-temperature fruit storage and regained at 2 weeks. This research suggests that low-temperature olive fruit storage may be beneficial, with a possibility of increasing oil yield and moderating the sensory quality of virgin olive oils. This study demonstrates that deeper insights into virgin olive oil quality changes during low-temperature fruit storage may be gained by studying volatile and phenolic compounds in addition to quality indices and physical appearance of the fruit.     

Multivariate analysis for the evaluation of fiber, sugars, and organic acids in commercial presentations of table olives

Table olives constitute an important part of the Mediterranean diet and the diet of many non-olive-producing countries. The aim of this work was to determine the fiber, sugar, and organic acid contents in Spanish commercial presentations of table olives and characterize them by means of a multivariate analysis. The selection of variables was carried out on the basis of a canonical analysis and their classification, according to processing styles and cultivars, through a linear discriminant analysis. Values of dietary fiber in table olives ranged from 2 to 5 g/100 g edible portion (e.p.). Some stuffing materials (almond, hot red pepper, and hazelnut) or the addition of capers produced a significant increase in the total dietary fiber in green olives. Glucose, fructose, and mannitol were usually found in the ranges of 0-55, 0-70, and 0-107 mg/100 g e.p., respectively. Succinic acid was detected only in green and directly brined olives (0-40 mg/100 g e.p.), while lactic and acetic acids were used within the ranges of 0-681 and 5-492.8 mg/100 g e.p., respectively. A multivariate analysis showed that fiber, mannitol, and succinic, lactic, and acetic acids can be used to discriminate between processing styles (95.5% correct assignations) and cultivars (61.20%). Current data can also be used in the evaluation of the dietary value of table olives.     

Risk assessment of repetitive movements in the citrus fruit industry

Musculoskeletal disorders are injuries of the muscles, nerves, tendons, ligaments, joints, cartilage, or spinal discs and are often classified as soft tissue injuries. They are the result of chronic or gradual development and are not caused by acute incidents such as slips, trips, or falls. The significance of this phenomenon prompted us to carry out a broader study of pathologies attributable to repetitive movements in the upper limbs within the citrus growing industry. Calabria, a very important region for citrus fruit growing in Italy, was chosen as the study area. The study analyzed the risks of repetitive movements for 180 workers on 35 different farms using the OCRA (Occupational Repetitive Actions) checklist method By analyzing the scores obtained in the different work phases, it was possible to determine the tasks that incur more risk in the citrus fruit industry. The OCRA checklist considers all the repetitive tasks involved in a complex job and estimates the level of exposure to each worker. In support of the specific aims of the present study, it is possible to identify a series of working conditions for which the level of risk may be reasonably estimated and for which it is possible to adopt a checklist system. The results of this study suggest that there must be a significant increase in the use of effective ergonomic interventions in the workplace in order to attain reductions in the number of local musculoskeletal complaints.     

Changes in free amino acids and sugars in potatoes due to sulfate fertilization and the effect on acrylamide formation

To examine how sulfur deprivation may affect acrylamide formation in cooked potatoes, three varieties of potato were grown under conditions of either severe sulfur deprivation or an adequate supply of sulfur. In all three varieties sulfur deprivation led to a decrease in acrylamide formation, even though the levels of sugars, which are acrylamide precursors, were higher in tubers of the sulfur-deprived plants. In one variety the concentration of free asparagine, the other precursor for acrylamide, was also higher. There was a very close correlation between the concentration of asparagine in the tubers expressed as a proportion of the total free amino acid pool and the formation of acrylamide upon cooking, whereas sugars were poorly correlated with acrylamide. In potatoes, where concentrations of sugars are usually limiting, competition between asparagine and other amino acids participating in the Maillard reaction may be a key determinant of the amount of acrylamide that is formed during processing.     

Amino sugars in fungal melanins and soil humic acids

Humic acids from six Brazilian topsoils (three Latosols and three Podzols) and five soil fungal melanins were hydrolysed and the released amino sugars qualitatively and quantitatively determined by capillary gas-liquid chromatography. Melanins were obtained from liquid culture media, synthesized with nitrate or asparagine as a source of N, of Stachybotrys atra, Aspergillus glaucus, Eurotium echinulatum and Hendersonula toruloidea. Glucosamine (48–60%), galactosamine (39–52%), and traces of mannosamine were detected in all humic acids. The total amino sugar content ranged from 1351 to 2287 mg kg^?1. In the fungal melanins analysed, mostly glucosamine (80–99%) and trace to small amounts of galactosamine and mannosamine (<10%) were found in amounts ranging from 192 to 635 mg kg^?1. The Occurrence of mannosamine in fungal melanins and fungal polysaccharides had not previously been found. The present study gives additional data to the theory that fungal melanins may play a role, as precursors, in the formation of soil organic matter.     

Evidence for microbial decomposition of organic acids during podzolization

Microbial aspects of podzolization were studied by percolating organic acids through sterile and non-sterile soil in columns. Six columns containing sand from a fluvioglacial sediment were percolated (90 mm d^?1) with mor extract and an oxalate-citrate solution. In three of these, sterilized soil solutions were used. Weathering was enhanced by organic acids which formed complexes with aluminium and iron. In the non-sterile soil columns weathering by organic acids was inhibited at 7–8 cm because the acids were degraded by microorganisms. Weathering was evident from colour change, contents of extractable aluminium and iron, and the micromorphology. Enhanced weathering in the sterile columns was also suggested by larger amounts of aluminium, iron, silica and base cations leached from the columns. Comparison of the output of aluminium, iron and silica from the sterile soil with that from the non-sterile soil, suggests that probably an aluminium-iron-silicate phase was formed in the deeper parts of the non-sterile columns.     

Changes in fruit antioxidant activity among blueberry cultivars during cold-temperature storage

Antioxidant activity, total phenolic content, anthocyanin content, and six other fruit characters including titratable acid concentration, soluble solids, firmness, and percentage of bruised berries were determined for nine blueberry (Vaccinium L. sp.) cultivars at harvest and at various postharvest intervals after storage at 5 degrees C. Berries from MSU-58, Brigitta, and Legacy stored successfully for 7 weeks, Bluegold stored for 3-5 weeks, Bluecrop, Elliott, and Nelson stored for 3 weeks, and Jersey and Little Giant stored for fewer than 3 weeks. During the time they retained marketable quality, one cultivar (MSU-58) demonstrated a 29% increase in antioxidant activity. None of the cultivars showed a significant decrease from the harvest antioxidant activity value during storage. Antioxidant activity, total phenolic content, and anthocyanin content were strongly correlated with each other (r = 0.87-0.99, P < 0.01). All three parameters were moderately correlated with soluble solids (r = 0.47, P < or =0.05; r = 0.44, P < or = 0.05; and r = 0.64, P < or = 0.01, respectively), and antioxidant activity and total phenolic content were both moderately correlated with pH (r = 0.53 and 0.49, respectively; P < or = 0.05). However, antioxidant activity, total phenolic content, and anthocyanin content showed no correlation with firmness, percent severely bruised berries, or weight loss. Antioxidant activity and total phenolic content at harvest both correlated with titratable acidity at harvest (r = 0.68, P < or = 0.05 and r = 0.70, P < or = 0.05, respectively) on a cultivar mean basis. Berries from Elliott were also harvested from plants at two levels of bush ripeness (30-50% and 60-80% ripe berries on plants) and separated into three fruit maturity classes on the basis of percent blue color. The level of bush ripeness had no significant effect on antioxidant activity, total phenolic content, or anthocyanin content; however, fruit maturity had a significant effect on antioxidant activity, total phenolic content, and anthocyanin content, and bush ripeness x fruit maturity interactions were significant for these three traits. Berries with 50-75% blue coloration harvested from bushes with 60-80% mature fruit showed a significant increase in antioxidant activity, total phenolic content, and anthocyanin content during the first 3 weeks in storage. Our results demonstrate that increases in antioxidant activity, total phenolic content, and anthocyanin content may occur in the blueberry during cold storage and are cultivar-dependent. The increases that occur in immature fruit, such as in Elliott, may be advantageous for producers who wish to delay marketing of the fruit.