Carbohydrate and acid contents of Gala apples and Bartlett pears from regular and controlled atmosphere storage.

Gala apples and Bartlett pears were harvested over two crop seasons at different maturities and growing sources then stored in refrigerated storage alone and in controlled atmosphere storage (1% O(2) plus 1% CO(2) or 2% O(2) plus 3% CO(2)). Before and after storage of 45 or 90 days, the juice from the fruit was examined for carbohydrate and acid compositions and contents. For Gala apples, the type and length of storage had no significant effect on juice carbohydrate and acid contents and compositions, whereas the time of harvest greatly influenced both parameters. Storage atmosphere did not affect the carbohydrate and acid contents and compositions of Bartlett pear juice; however, the source of the fruit and subsequent amount of ripening did appear to significantly cause changes in the same parameters. The carbohydrate and acid compositions and contents of Gala apple juice were within the compositional range for worldwide apple juice. Bartlett pear juice contained significantly greater concentrations of citric acid than shown in previously published studies.     

Impacts of farmland conversion to apple (Malus domestica) orchard on soil organic carbon stocks and enzyme activities in a semiarid loess region

Land‐use change often affects the sizes of soil organic carbon (SOC) stocks and the activities of soil enzymes. Responses of relevant soil quality indices caused by farmland conversion to orchard are largely unknown in the semiarid loess regions. This study was conducted at orchard sites, which have been under very intensive cultivation, to evaluate the impacts of farmland conversion to apple (Malus domestica) orchard on SOC stocks and soil enzyme activities in the semiarid loess region of Weibei, Shaanxi province, China. The spatial and temporal changes in a variety of soil quality indices were measured for the 0–100 cm soil profile in apple orchards of three age groups (< 10 y, juvenile; 10–15 y, mature; > 15 y, over‐mature) and adjacent farmlands (control). After farmland conversion, total SOC (TOC) content and density and soil alkaline phosphatase activity significantly decreased, while soil catalase activity increased for the 0–100 cm soil profile. The labile SOC (LOC) content, its proportion to TOC content, and carbon management index (CMI, changes in the total content and lability of SOC) significantly increased in the 0–40 cm soil layer, whereas soil urease and invertase activities only increased in the 0–20 cm layer (P < 0.05). With increasing age of apple orchards, SOC stocks significantly increased after 10 y, being more than 10% larger in mature and over mature orchards than in adjacent farmlands. The LOC content and CMI value also had an increasing trend, while soil enzyme activities showed different response patterns. There were significant correlations between soil enzyme activities, SOC fractions, and CMI value (P < 0.05). We concluded that farmland conversion to apple orchard affected soil quality by reducing SOC stocks in the soil profile and changing SOC content as well as soil enzyme activities at various depth intervals. Long‐term apple cultivation was effective to restore SOC stocks, although it took over a decade to rebuild a new increasing trend after farmland conversion.     

Long-term storage of Pink Lady apples modifies volatile-involved enzyme activities: consequences on production of volatile esters

Pink Lady apples were harvested at commercial maturity and stored at 1 degrees C and 92% relative humidity under either air or controlled atmosphere conditions (2 kPa O 2:2 kPa CO 2 and 1 kPa O 2:1 kPa CO 2) for 27 weeks. Data on the emission of volatile compounds and on the activity of some related enzymes in both skin and flesh tissues were obtained during subsequent shelf life at 20 degrees C. Major effects of storage atmosphere and poststorage period were observed on the emission of volatile esters and their precursors. Changes in the production of volatile esters were partly due to alterations in the activity of alcohol o-acyltransferase, but the specific esters emitted by fruit after storage also resulted largely from modifications in the supply of the corresponding substrates. Samples stored under air were characterized by higher availability of acetaldehyde, whereas those stored under CA showed enhanced emission of the alcohol precursors ethanol and 1-hexanol (2 kPa O 2) and 1-butanol (1 kPa O 2), with accordingly higher production of ethyl, hexyl, and butyl esters. Multivariate analysis revealed that a large part of the observed differences in precursor availability arose from modifications in the activity of the enzymes considered. Higher pyruvate decarboxylase activity in air-stored fruit possibly accounted for higher acetaldehyde levels in these samples, while storage under 1 kPa O 2 led to significantly decreased lipoxygenase activity and thus to lessened production of 1-hexanol and hexyl esters. Low acetaldehyde availability together with enhanced hydroperoxide lyase and alcohol dehydrogenase levels in these fruits are suggested to have led to higher emission of 1-butanol and butyl esters.     

Comparison of the volatile profile and sensory analysis of 'Golden Reinders' apples after the application of a cold air period after ultralow oxygen (ULO) storage

All efforts to improve fruit quality are rewarded when consumers are satisfied after tasting the fruit. Apples are often stored under controlled atmosphere conditions to preserve them over time, but this frequently results in a loss of flavor. The aim of this work, which was based on two seasons, was to evaluate the influence of a period of short-term air storage (periods of 2 and 4 weeks) after removal from ultralow oxygen (ULO) storage (1 kPa of O(2)/1 kPa of CO(2)) with respect to increases in volatile compound emissions and the effect on standard and sensory quality in 'Golden Reinders' apples. The results showed that emissions of 26 volatile compounds increased as a result of ULO + 2 weeks or ULO + 4 weeks of storage. However, the results of tastings involving a panel of consumers and trained experts revealed that this increase was not matched by corresponding increases in either the degree of consumer preference or flavor attributes.     

Changes in enzyme activities of spruce (Picea balfouriana) forest soil as related to burning in the eastern Qinghai-Tibetan Plateau

The effect of forest fire on soil enzyme activity of spruce (Picea balfouriana) forest in the eastern Qinghai-Tibetan Plateau was assessed. Six specific enzymes were chosen for investigation: invertase, acid phosphatase, proteinase, catalase, peroxidase and polyphenoloxidase. It was found that the activities of invertase and proteinase were reduced by burning, but the activities of acid phosphatase, polyphenoloxidase and peroxidase increased. Meanwhile, burning significantly (P < 0.05) resulted in the decrease of concentrations of available N and K of 0–20 cm depth layer soil, and significantly (P < 0.05) decreased concentrations of organic matter content, total N and P, as well as available N, P and K in soil at both 20–40 and 40–60 cm depths except for available P at 20–40 cm soil depth. These results illustrated that burning could influence the enzyme activities and chemical properties of soil not only of upper but also lower soil layers. Correlation analysis indicated that invertase activities in 0–20 cm depth layer soil were significantly positively correlated with organic matter, total N and P, as well as available N and P. Furthermore, all six enzymes studied were sensitive to fire disturbance, and thus could be used as indicators of soil quality. Our study also showed that soil enzyme activities were associated with soil depth, decreasing from top to bottom in both burned and unburned spruce forests. The distribution pattern of soil enzyme activities suggested that the rate of organic matter decomposition and nutrient cycling depended on soil depth, which had important structural and functional characteristics in nutrient cycling dynamics and implications in plantation nutrient management. The finding that burning effects on enzyme activities and soil properties between different soil layers were homogenized was attributed to the 8-years’ regeneration of forest after burning.     

Changes in compositional parameters of tubers of potato (Solanum tuberosum) during low-temperature storage and their relationship to chip processing quality

A four-year study of a number of compositional parameters of potato tubers during low-temperature storage was conducted to examine the compositional differences between cold-tolerant (low sugar-accumulating) and cold-sensitive (high sugar-accumulating) tubers in relation to potato chip processing quality. Compositional parameters analyzed included sucrose, reducing sugars, nitrogen, protein, ascorbic acid, and dry matter content. Pearson correlation analysis of the data illustrated that chip color was most closely correlated with reducing sugar concentration. Multiple regression analysis revealed that the relative contribution of each parameter to chip color varied greatly among the cultivars and selections evaluated and from season to season. This analysis demonstrates that the quantitative relationships between the measured compositional parameters and chip color were not sufficient to provide a general predictive index of chip color quality for tubers processed directly from low-temperature storage.     

Changes in enzyme activities of spruce (Picea balfouriana) forest soil as related to burning in the eastern Qinghai-Tibetan Plateau

The effect of forest fire on soil enzyme activity of spruce (Picea balfouriana) forest in the eastern Qinghai-Tibetan Plateau was assessed. Six specific enzymes were chosen for investigation: invertase, acid phosphatase, proteinase, catalase, peroxidase and polyphenoloxidase. It was found that the activities of invertase and proteinase were reduced by burning, but the activities of acid phosphatase, polyphenoloxidase and peroxidase increased. Meanwhile, burning significantly (P < 0.05) resulted in the decrease of concentrations of available N and K of 0–20 cm depth layer soil, and significantly (P < 0.05) decreased concentrations of organic matter content, total N and P, as well as available N, P and K in soil at both 20–40 and 40–60 cm depths except for available P at 20–40 cm soil depth. These results illustrated that burning could influence the enzyme activities and chemical properties of soil not only of upper but also lower soil layers. Correlation analysis indicated that invertase activities in 0–20 cm depth layer soil were significantly positively correlated with organic matter, total N and P, as well as available N and P. Furthermore, all six enzymes studied were sensitive to fire disturbance, and thus could be used as indicators of soil quality. Our study also showed that soil enzyme activities were associated with soil depth, decreasing from top to bottom in both burned and unburned spruce forests. The distribution pattern of soil enzyme activities suggested that the rate of organic matter decomposition and nutrient cycling depended on soil depth, which had important structural and functional characteristics in nutrient cycling dynamics and implications in plantation nutrient management. The finding that burning effects on enzyme activities and soil properties between different soil layers were homogenized was attributed to the 8-years’ regeneration of forest after burning.     

Pre-extraction preparation (fresh, frozen, freeze-dried, or acetone powdered) and long-term storage of fruit and vegetable tissues: effects on antioxidant enzyme activity

Activities of the antioxidant enzymes ascorbate peroxidase, catalase, dehydroascorbate reductase, glutathione reductase, guaiacol peroxidase, monodehydroascorbate reductase, and superoxide dismutase were assayed in honeydew (Cucumis melo L.) fruit and spinach (Spinacia oleracea L.) leaves either as fresh, frozen to -80 degrees C, frozen in liquid nitrogen, freeze-dried, or acetone powder, representing the various ways tissues are treated prior to enzyme extraction. Treated tissues were analyzed following treatment or stored for up to 8 weeks at -80 degrees C. Enzyme activities in fruit frozen with or without liquid nitrogen and leaves frozen with or without liquid nitrogen or freeze-dried were equal to those of fresh tissue. Enzyme activities in freeze-dried or acetone-powdered fruit and leaves and in acetone-powdered tissues were significantly higher or lower than those in fresh tissue. Enzyme activities in both tissues frozen with or without liquid nitrogen and stored for 8 weeks at -80 degrees C changed little; those in freeze-dried and acetone-powdered tissues, however, significantly increased/decreased over the same period. Fresh tissue should be used in antioxidant enzyme assays, but if storage is necessary, tissues should be placed directly into a -80 degrees C freezer.     

Assessment of storage protein variation in relation to some morphological characters in a sample of Spanish landraces of common wheat (Triticum aestivum L. ssp. aestivum)

Fifty nine Spanish landraces of common wheat belonging to differentagrotypes were evaluated with four morphological spike characters and 11 seedprotein loci in order to study the level of agreement between the agrotypeclassification and the morphological and biochemical variation of the wheats. Asa result of the work 22 new gliadin alleles were found and 12 of them werecatalogued. Multivariate and cluster analysis performed on the two sets of data(morphological plus biochemical and biochemical only) showed that there was aclear relationship between seed protein composition and the wheat classificationfor the agrotypes Barbilla, Candeal andNegrete. For the other groups, agrotype classification was notconsistent with the variation for biochemical characters although, some allelesin common were found except for the Jeja type. Morphologicaltraits revealed that they could be useful as first step in discriminating amongagrotypes. In contrast, biochemical markers showed that genetic variation amongaccessions was higher than among agrotypes. The protein lociGli-B1,Gli-A2,Gli-D2 andGli-A1 were shown to be the mostpolymorphic and useful in discriminating between the accessions studied.     

Volatile composition of coffee berries at different stages of ripeness and their possible attraction to the coffee berry borer Hypothenemus hampei (Coleoptera: Curculionidae)

The analysis of volatile emissions of coffee berries in different physiological states of ripeness was performed using dynamic headspace and gas chromatography/mass spectrometry analysis for Coffea arabica, var. Colombia. The composition of the volatiles emitted by coffee berries is dominated by very high levels of alcohols, mainly ethanol, in all stages of ripeness in comparison with other compounds. Overripe coffee berries have high volatile emissions and show a composition dominated mainly by esters followed by alcohols, ketones, and aldehydes. The lowest level compounds were monoterpenes. 2-Methyl furan was detected in various ripening stages; this compound has not been previously reported as a coffee berry volatile. The presence of ethanol and other alcohols in the volatile composition might explain the effectiveness of using traps with mixed alcohols for detection and capture of coffee berry borers.     

Release of angiotensin I converting enzyme (ACE) inhibitory activity during in vitro gastrointestinal digestion: from batch experiment to semicontinuous model

Gastrointestinal digestion is of major importance in the bioavailability of angiotensin I converting enzyme (ACE) inhibitory peptides, bioactive peptides with possible antihypertensive effects. In this study, the conditions of in vitro gastrointestinal digestion leading to the formation and degradation of ACE inhibitory peptides were investigated for pea and whey protein. In batch experiments, the digestion simulating the physiological conditions sufficed to achieve the highest ACE inhibitory activity, with IC(50) values of 0.076 mg/mL for pea and 0.048 mg/mL for whey protein. The degree of proteolysis did not correlate with the ACE inhibitory activity and was always higher for pea than whey. In a semicontinuous model of gastrointestinal digestion, response surface methodology studied the influence of temperature and incubation time in both the stomach and small intestine phases on the ACE inhibitory activity and degree of proteolysis. For pea protein, a linear model for the degree of proteolysis and a quadratic model for the ACE inhibitory activity could be constituted. Within the model, a maximal degree of proteolysis was observed at the highest temperature and the longest incubation time in the small intestine phase, while maximal ACE inhibitory activity was obtained at the longest incubation times in the stomach and small intestine phase. These results show that ACE inhibitory activity of pea and whey hydrolysates can be controlled by the conditions of in vitro gastrointestinal digestion.     

Degradation of gluten by proteases from dry and germinating wheat (Triticum durum) seeds: An in vitro approach to storage protein mobilization

Vital gluten was used as an ideal substrate to investigate the role of some proteases in storage protein degradation. Aspartic proteinase and carboxypeptidase were identified as endogenous enzymes adsorbed on gluten and their optimum pH values determined. SDS-PAGE of soluble products released by gluten digestion revealed that the activity of these proteases plays a minor role in protein mobilization, whereas cysteine proteinase, purified from wheat seeds at the fourth day of germination, is extremely effective, producing a remarkable protein degradation in short times. Synergistic effects of aspartic and cysteine proteinase were not observed. Spin labeling of the sulfhydryl groups of gluten proteins enabled a comparative EPR investigation of the consequences of proteolytic degradation on gluten elasticity. It was found that storage protein mobilization brings a loss of elasticity to the polymeric network of gluten, which is particularly marked when the hydrolysis is performed by cysteine proteinase.     

Nitrogen fixation (C2H2 reduction) in a salt marsh: Its relationship to temperature and an evaluation of an in situ chamber technique

A temperature controlled chamber for the in situ measurement of nitrogen fixation (acetylene reduction) in a vegetated salt marsh is described. Rates of acetylene reduction activity (ARA) were linear during a 9 h incubation. Measurements of acetylene penetration into the sediment indicate that the chamber technique measures ARA within the top 2–4 cm of the sediment column. This depth of penetration accounted for approx. 60% of the total ARA in the sediment column. Measurements of in situ ARA in three zones of a vegetated salt marsh (tall, medium and short height Spartina alterniflora) over a year were positively correlated with seasonal temperature variations. About 70–80% of the seasonal variation in ARA was explained by the Arrhenius relationship: ARA (μmol C₂H₄m⁻²h⁻¹)=α exp(−β/fT); where T is the ambient air temperature (°C) and α and β are constants. The constant α in this model increased from 20.1 to 40.5 while β increased from 17.5 to 20.7 along a transect from the tall to short height-form S. alterniflora communities. These differences suggest that there is spatial variability within the salt marsh among the variables that affect nitrogen fixation.     

Recovery in soil cover and vegetation structure after ancient landslide in mountain fens under Caltho-Alnetum community and response of soil microarthropods (Hexapoda: Collembola) to natural restoration process

Purpose

The objective of this study was to determine the long-term environmental changes induced by ancient landslide in the mountain fen. Attempts were made to demonstrate the progress of the soil cover restoration process about 200 years after the landslides and associated with changes in vegetation and soil microarthropod biodiversity and occurrence pattern associated with the restoration of soil cover.

Material and methods

The study covered mountain fen of the Caltho-Alnetum in the Babiogórski National Park in Outer Flysch Carpathians, Poland, where ancient landslide deposits are causing disturbance in fen hydrologic regime and over time related to various rate of fen area natural restoration processes. The drill test has been used to assess changes in layering and thickness of the fen soils. The following soil parameters, such as pH and total organic carbon content, were determined at each distinguish layer. The diversity and distribution pattern of soil microarthropods, represented by Collembola, was examined in two parts of the fen: restored and not-restored. The soil parameters, such as pH, electrical conductivity, total exchangeable base, total organic carbon, and nitrogen content, were determined in the soil samples simultaneously. The assessment of the vegetation structure recovery within studied mountain fen after landslide was referred to average parameters of the community completed for other natural mountain fens under the Caltho-Alnetum community. The research results were statistically verified.

Results and discussion

The test drillings showed that landslides change soil layering, site-specific soil properties of mountain fen such as chemistry (the statistically significant differences were noted only in the case of total organic carbon content), vegetation structure, and soil microarthropod communities. By changing site-specific conditions, landslides influence on the biodiversity and peatland ecosystems functioning.

Conclusion

Our results clearly demonstrate that the landslide itself initiated a complex and lengthy process of changes in biological aspects of peatlands including the biodiversity of the underground fauna and plant community. Soil microarthropod communities represented by Collembola can be used as a good indicator of mountain fen restoration process.