Changes In Dry Matter Content Research Articles

Heterofermentative Lentilactobacillus buchneri and low dry matter reduce high-risk antibiotic resistance genes in corn silage by regulating pathogens and mobile genetic element

The study of antibiotic resistance in the silage microbiome has attracted initial attention. However, the influences of lactic acid bacteria inoculants and dry matter (DM) content on antibiotic resistance genes (ARGs) reduction in whole-plant corn silage remain poorly studied. This study accessed the ARGs’ risk and transmission mechanism in whole-plant corn silage with different DM levels and treated with Lactiplantibacillus plantarum or Lentilactobacillus buchneri. The macrolide and tetracycline were the main ARGs in corn silage. The dominant species (Lent. buchneri and Lactobacillus acetotolerans) were the main ARGs carriers in whole-plant corn silage. The application of Lent. buchneri increased total ARGs abundance regardless of corn DM. Whole-plant corn silage with 30 % DM reduced the abundances of integrase and plasmid compared with 40 % DM. The correlation and structural equation model analysis demonstrated that bacterial community succession, resulting from changes in DM content, was the primary driving factor influencing the ARGs distribution in whole-plant corn silage. Interestingly, whole-plant corn silage inoculated with Lent. buchneri reduced abundances of high-risk ARGs (mdtG, mepA, tetM, mecA, vatE and tetW) by regulating pathogens (Escherichia coli), mobile genetic elements (MGEs) genes (IS3 and IS1182), and this effect was more pronounced at 30 % DM level. In summary, although whole-plant corn silage inoculated with Lent. buchneri increased the total ARGs abundance at both DM levels, it decreased the abundance of high-risk ARGs by reducing the abundances of the pathogens and MGEs, and this effect was more noticeable at 30 % DM level.

The Effect of Electrical Conductivity on Fruit Growth Pattern in Hydroponically Grown Tomatoes

Osmotic stress enhances fruit quality, including the dry matter content, in tomatoes (Solanum lycopersicum L.). This study aimed at providing further insight into the precision control of fruit yield and quality on the long-term moderate osmotic stress conditions in tomato fruit production. We compared the growth pattern between fruits of two cultivars, typical Japanese and Dutch cultivars, under two different nutrient concentrations (2.3 and 5.0 dS·m−1) to understand the effect of electrical conductivity (EC) on dry mass and water content of fruits. The experiment was performed with a rockwool bag culture system in a controlled greenhouse. Increasing EC resulted in an approximately 20% decrease in fruit yield and a 0.5–1% increase in fruit dry matter content in both cultivars. This yield reduction was not caused by the fruit number, but by an approximately 25% decrease in individual fresh fruit weight. Non-linear models were used to describe the changes in dry matter content, water content, and dry weight of tomato fruit as a function of cumulative temperature. The decay rate of dry matter content in the fruit decreased with high EC treatments in the Japanese cultivar. The points at which the rates of changes in water and dry weight increased the in fruit were around 585 and 480 °C-days after anthesis, respectively, under the low EC condition. Rates of water increase in the fruit were changed by high EC treatment, while the shifts were opposite with respect to the cultivars. Dry weight increase in the fruit was not affected by EC treatment. Collectively, our findings clarify the effect of EC on the fruit growth characteristics of Japanese and Dutch tomato cultivars, and provide new insights into the yield of high-Brix tomato cultivation.

High Light Intensity Applied Shortly Before Harvest Improves Lettuce Nutritional Quality and Extends the Shelf Life.

The effect of light intensity applied shortly before harvest on the nutritional quality, postharvest performance, and shelf life of loose-leaf lettuce (Lactuca sativa L. cv. Expertise RZ Salanova®) was investigated. Lettuce was grown either in a greenhouse with supplemental high-pressure sodium light (Experiment 1, EXP 1) or in a climate room under white LED light (Experiment 2, EXP 2). In both experiments full grown plants were transferred to a climate room for the End of Production (EoP) light treatments during the last week of cultivation. During EoP lighting plants were exposed to different intensities (0, 110, and 270 μmol m–2 s–1 in EXP 1; 50, 210, and 470 μmol m–2 s–1 in EXP 2) from white-red LEDs for 6 (EXP 2) or 7 days (EXP 1). Mature leaves were then harvested and stored in darkness at 10°C to study the postharvest performance. Changes in dry matter content, total ascorbic acid, and carbohydrates (including glucose, fructose sucrose, and starch) levels were determined during EoP lighting and during the subsequent shelf life as indicators of lettuce nutritional quality. Quality aspects (appearance, texture, and odor) were accessed during the shelf life as indicators of postharvest performance. In both experiments, high light intensities applied in EoP lighting increased dry matter percentage and contents of ascorbic acid (AsA) and carbohydrates at harvest and these increased levels were maintained during the shelf life. Increased light intensity in EoP treatment also extended the shelf life. The levels of AsA and carbohydrates at harvest correlated positively with the subsequent shelf life, indicating that the prolonged shelf life relies on the improved energy and antioxidant status of the crop at harvest.

Physiological status and nutritional condition of cultured juvenile Thenus australiensis over the moult cycle.

The moult cycle is arguably the most critical aspect of crustacean biology and is associated with dramatic changes in behaviour, physiology and condition. Here we describe the first detailed investigation of the combined changes in morphology, physiological status and nutritional condition over the moult cycle of juvenile T. australiensis. Haemolymph refractive index (measured as Brix) was evaluated as a non-destructive method for predicting physiological status and nutritional condition. Post-moult, inter-moult and pre-moult stages were identifiable by microscopic examination of the pleopod distal tips, though differentiation of the pre-moult substages was not possible using this technique. Monitoring of ecdysial suture lines on the exoskeleton gill chambers was found to be highly useful for visually determining progression through the pre-moult stage and predicting the timing of ecdysis. A classical pattern of inter-moult growth was observed where size and wet weight remained relatively uniform over the moult cycle while highly significant changes in whole-body composition were simultaneously observed over time. Growth was most evident by changes in dry weight and dry matter content which more than doubled by the onset of pre-moult. Changes in dry matter content were generally mirrored by Brix and whole-body crude protein, total lipid and gross energy content. Brix strongly correlated with dry matter content and significant correlations were also found for all other primary measures of nutritional condition. Typical moult-related changes were also found for circulating ecdysteroids. This study clearly demonstrates pronounced cyclical changes in physiology and condition of juvenile T. australiensis over a typical moult cycle. The significant correlations between haemolymph and whole-body composition validates Brix as a practical and non-destructive method to objectively assess physiological status, nutritional condition and quality in T. australiensis and further demonstrates its potential for individual crustacean assessment in experimental research and practical commercial applications.

Evaluation of LiDAR scanning for measurement of yield in perennial ryegrass

mproving pasture yields is a primary goal for plant breeders. However, measuring and selecting for yield is a major bottleneck in breeding, requiring methods that are laborious, destructive, and/or imprecise. A computerised scanner developed in Canterbury using LiDAR (light detection and ranging) technology was evaluated in the Waikato on perennial ryegrass paired-row breeding plots. At eight timepoints, all plots were scanned prior to mechanical defoliation and recording of fresh weight (FW) and dry matter (DM) yield on a random subset of plots. Yield data on 1206 FW and 504 DM samples were compared with LiDAR scan results on a seasonal basis by regression. Winter, spring, summer and autumn correlation with FW were R2 = 0.81, 0.92, 0.94 and 0.90, respectively, and with DM yield R2 = 0.87, 0.73, 0.87 and 0.79, respectively. These results indicate LiDAR estimation of DM yield was accurate within seasons for the paired-row breeding plots, although it was sensitive to large changes in dry matter content (%) among seasons, which may require seasonal algorithms to correct for this variation if this technology is to be adopted. In conclusion, the scanner could be useful in removing a major bottleneck in perennial ryegrass breeding and may have application for agronomy and farm management in cases where precise non-destructive real-time estimation of DM yield are of value.

Relationship between dry matter content at harvest and maturity index and post-harvest quality of ‘Fuji’ apples

Abstract Two experiments were carried out to evaluate the relationship between dry matter content (DMC) and maturity index of ‘Fuji’ apple fruit sports (‘Mishima’, ‘Fuji Select’ and ‘Fuji Suprema’) during the final stage of fruit growth, and the relationship between DMC at harvest and the post-harvest fruit quality. Fruit were harvested from orchards of three regions (Caçador, São Joaquim and Vacaria), on two rootstocks (M9 and Marubakaido with M9 interstock). In experiment 1 (2014), fruit were periodically sampled beginning 83 days before the commercial harvest period. In experiment 2, fruit were harvested at optimum maturity for long-term storage and stored in air at 0.5 ºC (2014) or after optimum maturity for long-term storage and stored in controlled atmosphere at 0.7 ºC (2014 and 2015). Apple fruit maturity on the tree was characterized by decreased flesh firmness and increased starch index and soluble solids content (SS) and by a small change in DMC. DMC at harvest was correlated with flesh firmness and SS in one of two years, but DMC was not correlated with the incidence of disorders after storage. The results show that DMC at harvest is not suitable as a maturity index of ‘Fuji’ apples, and its use as a post-harvest quality predictor is not consistent between crop years.

Abscisic acid and its metabolites are involved in drought tolerance in four native species of Patagonian semiarid shrublands (Argentina)

Drought is the main stress that affects growth of native species of Patagonian Monte. Physiological and biochemical traits with functional roles in adaptation to drought are still scarce in native species. The aim of this study was to evaluate changes in dry matter content and abscisic acid (ABA) and its metabolites (phaseic acid-PA, dihydrophaseic acid-DPA, ABA conjugated with glucose-ABA-GE) level in green leaves and fine roots of four native species during contrasting seasons regarding water availability. Results show that grasses had higher leaf dry matter content (LDMC) and root dry matter content (RDMC) than Lycium chilense shrub and LDMC decreased during autumn in Larrea divaricata. In green leaves, there was an interaction between species and seasons for ABA and PA contents. L. divaricata had high ABA content during spring and low ABA content during autumn; while L. chilense showed the opposite pattern. During spring, drought tolerant species had high PA content while drought avoidant species had low PA content, and during autumn these species showed the opposite pattern. ABA-GE content was highest in L. chilense green leaves. In fine roots, ABA content was highest in L. divaricata and during spring PA was higher in L. divaricata than P. ligularis and L. chilense. PA was the only metabolite that decreased in L. divaricata during autumn. Results showed that ABA homeostasis maintains the functioning of different life forms with different drought resistance strategies in Patagonia semiarid shrublands. In green leaves of the drought avoidant L. chilense shrub, the ABA conjugation pathway was active in both seasons. During spring, the most drought tolerant L. divaricata showed highest activation of ABA synthesis and ABA oxidation pathways. During autumn L. chilense showed highest activation of ABA synthesis and together with P. ligularis showed active the ABA oxidation pathway.

Effect of intermittent feeding and oat hulls to improve phytase efficacy and digestive function in broiler chickens

ABSTRACT1. Two trials were carried out to investigate the impact of intermittent feeding and oat hulls as methods to stimulate the anterior digestive tract in broiler chickens.2. In Trial 1, 7-d-old broilers were placed 4 per cage in 48 cages and fed either ad libitum or intermittently on a diet with 50 g/kg of either oat hulls or cellulose, with or without 1000 FTU phytase, in a 2 × 2 × 2 factorial arrangement. Ad libitum fed birds had two 4-h dark periods with 1-h light in between, while intermittently fed birds in addition had restricted access to feed through four 1 h feeding bouts.3. In Trial 2, 144 broiler chickens were divided amongst 12 pens which were intermittently fed on the same diets as in Trial 1 in a 2 × 2 factorial arrangement. At 34 d of age, after 16 h feed withdrawal, birds were fed for 1 h, followed by dissection of 4 birds per treatment every hour for 9 h. Contents from different segments of the digestive tract were collected quantitatively to assess dry matter (DM) and starch flow.4. In Trial 1, phytase improved performance and nutrient availability, while oat hulls and intermittent feeding improved some measures of nutrient availability. Intermittent feeding augmented the effect of phytase on myo-inositol hexakisphosphate (IP6) degradation in the anterior digestive tract.5. In Trial 2, birds filled up their crop and slowly passed these contents on to lower segments of the digestive tract. Already 1 h after commencement of feeding, the entire length of the small intestine was filled with DM, and no significant changes in DM content were observed before 4–5 h later, when the small intestine gradually became emptied. The tendency for a higher initial load of DM and starch in birds without oat hulls seems to support the hypothesis that one important function of the gizzard is feed-flow regulation.6. In conclusion, the anterior digestive tract seems to have an important regulative function in broiler chickens when stimulated by intermittent feeding or structural components. More research is needed in order to elucidate the role of the crop and gizzard for phytase function.

Wound healing and dry matter content of orange-fleshed sweetpotato cultivars as influenced by curing methods

Abstract Curing in sweetpotato is a crucial pre- or postharvest practice that could guarantee improved shelf life,but rarely practised by sweetpotato farmers in Sub-Saharan Africa, principally due to lack of knowledge. Wound healing ability of cultivars has been associated with good root storability. In this study, two orange fleshed sweetpotato cultivars (Apomuden and Nane) were either cured in-ground by dehaulming prior to harvest or field-piled over a seven-day period to study their responses to wound healing and changes in dry matter content. Apomuden is a low dry matter content(19%) variety in Ghana while Nane is a high dry matter content (27%) farmer cultivar under evaluation for formal release. A potato peeler was used to deliberately create the wounds on 21 storage roots. The curing treatment was applied and the subsequent post-treatment quality status of the storage roots was monitored daily over a seven-day period. Wound healing ability was scored as follows: 0 = no lignification, 0.5 = patchy lignification and1= complete lignification. Wound healing ability score was not significantly different for Apomuden and Nane (0.83,0.78, respectively; p = 0.120). However, storage roots curedby field-piled curing method resulted in significantly better wound healing ability than dehaulming (0.86, 0.75,respectively, p = 0.001). Over the seven-day curing period,Nane had a significantly higher and stable dry mattercontent compared with Apomuden (p = 0.008), whose dry matter content was lower and fluctuating. The field-piled curing resulted in higher (p = 0.020) dry matter content,24%, compared with in-ground curing (22%). The field piled curing method, which can easily be adopted by sweetpotato farmers, increased the dry matter content of the storage roots; therefore, it could potentially reduce the post-harvest losses in sweetpotato. The high dry matter content of Nane is a desirable root quality attribute for orange-fleshed cultivars and could augment existing cultivars in Ghana.

Towards the development of innovative multi-mycotoxin reference materials as promising metrological tool for emerging and regulated mycotoxin analyses.

The interest in LC-MS/MS multi-mycotoxin methods unveiled an urgent need for multi-mycotoxin reference material. A multi-fusariotoxin, including deoxynivalenol (DON); zearalenone (ZEN); T-2 toxin (T-2); HT-2 toxin (HT-2); enniatin A, A1, B, and B1 (ENNs); and beauvericin (BEA), contaminated wheat flour was obtained by inoculation Fusarium spp. strains. The candidate material has successfully passed the homogeneity test and submitted to an international interlaboratory study achieved by 19 laboratories from 11 countries using their routine analytical method. The dispersion of the results for ZEN and BEA did not allow the derivation of reliable consensus values, while the assignment was only possible for DON, HT-2, T-2, and ENN A. No link was found between the methods used by the participants and the results. Significant changes in dry matter contents (≥±1.4% of the initial dry matter) and significant changes in ergosterol contents (≥±10%) did not occur. Using the mycotoxin contents in wheat flour stored at -80°C as reference values, statistically significant decreases were observed only for T-2 contents at +24°C, in contrast to the storage at -20 and +4°C. For the other involved toxins, the candidate material was found to be stable at -20, +4, or +24°C. Based on the T-2 decreases, a shelf life of 6years was derived from isochronous study when the material is kept at -20°C. At room temperature (e.g., +24°C) or higher, this time validity drastically decreases down to 6months. The development of this metrological tool is an important step towards food and feed quality control using multi-mycotoxin analyses. In vivo animal experiments using multi-mycotoxin-contaminated feeds dealing with the carryover or mitigation could further benefit from the methodology of this work.

Dry matter, Free Sugar and Starch Changes in Tuber Regions of White Yam (Dioscorea rotundata Poir.), and the Effect of Storage Environment

This study was conducted to determine the changes in dry matter (DM), free sugar (FS) and starch contents in the three yam (D. rotundata) tuber regions under two storage environmental conditions (natural light- yam barn, or and darkness). Three varieties of D. rotundata (alaako, Dodoro and Odo) were studied. The dry matter content of the Head region was the highest (28.6%), followed by the Middle (26.9%) and Tail (22.3%) regions. Change in dry matter content of the tuber is mainly due to rapid changes in the dry matter content of the Tail region over time. Storage environment significantly (P< 0.05) affected dry matter content of the three tuber regions at 8 and 16 weeks in storage (WIS). Head regions per variety were lower in dry matter when stored under Light than in the Dark at 8 WIS, while the reverse was the case for the Tail. This may relate to the release of endodormancy. By 16 WIS, when tubers stored under Light had well developed sprouts and those stored in the Dark only showed the first sign of sprouting, all Head regions had higher dry matter content under Light than in Dark storage. This may be due to the presence of sprouts. Storage environment did not significantly affect starch content at the various tuber regions. Head regions had higher percentage free sugar content under Light than Dark storage, and these effects were manifested between 8 and 16 WIS.

Osmotic Concentration of Gooseberry Fruits - The Influence of Temperature, Time and Pretreatment Methods on Mass Transfer and Total Polyphenol and Organic Acid Content.

The objective of the study is to assess the influence of temperature, time and enzymatic pretreatment on the osmotic concentration of gooseberry fruits (cultivar Biały Triumf). The fruits were osmotically concentrated in a sucrose solution at 65 °Brix and 40 to 70 °C for 5 to 240 min. Two experimental procedures were employed. In the first procedure, prior to concentration the fruits were immersed in the solution containing lipolytic enzymes, and then in the solution containing pectinolytic enzymes. In the second procedure, pectinolytic enzymes were added to the sucrose solution. The kinetics of the osmotic concentration was studied based on the changes in dry matter content, water loss, and solid gain. Higher temperature and longer process time led to higher values of the mentioned parameters. After 1 h of concentration at 40 °C, dry matter content was 13.9%, while at 70 °C it was 20.4%. The use of pectinolytic enzymes during osmotic concentration resulted in higher effectiveness of the process. After 2 h of concentration with the use of pectinolytic enzymes, solid gain was seven times higher than that in the control sample. Enzymatic treatment with lipase and pectinase before concentration also increased solid gain during osmotic concentration (up to twelve times after 2 h at 40 °C). The lower processing temperature, the higher retention of phenolic compounds in fruits was observed. The retention of phenolics was the highest at 40 °C (92.2% at 2 h). Among organic acids (malic, shikimic and citric), the highest retention was exhibited by citric acid; at 1 h of concentration, its fraction in the obtained fruit syrup content was from 95.9 to 83.1% as compared to the starting material.

On the Determination of Water Content in Biomass Processing

Processing of lignocellulosic materials to fuels such as methane and bioethanol may involve several processing steps including pretreatment, saccharification, fermentation, and anaerobic digestion. The amounts of substrate used in these processes are usually based on dry matter content, and the processes themselves typically lead to a change in dry matter content. Thus, it is of great importance to be able to measure dry matter accurately. Dry matter content is commonly determined by measuring loss of water during oven drying. We have used Karl Fischer (KF) titration to measure the water content in a wide range of biomass fractions and have compared these data to results obtained by oven drying. This revealed considerable differences for all tested materials. For lignocellulosic materials, oven drying tends to overestimate dry matter content for untreated material. On the other hand, oven drying generally underestimates dry matter content in pretreated materials due to loss of organic volatiles. These differences have major consequences for the calculation of mass balances and yields in bioprocessing. The KF method gives more accurate water determination than oven drying due to the unique selectivity of the analysis. The method is suitable for the analysis of lignocellulosic biomasses and is particularly useful for determination of water content in pretreated materials, where oven drying usually underestimates the dry matter content due to loss of volatiles.

Some physiological changes in Waldsteinia trifolia (Roch.) leaves in different months of the year

The study concerned an evergreen herbal plant <i>Waldsteinia trifolia</i> Roch. This species can be found more and more often in garden plantings in Poland. The aim of the study was to estimate the content of photosynthetic pigments, anthocyanins and dry matter as well as the permeability of cytoplasmatic membranes of <i>Waldsteinia</i> leaves. Plants grew in an ornamental plant collection at the premises of the Faculty of Horticulture of the Agricultural University in Kraków. The study was conducted in 2006 and 2007 in the following months: March, May, June, September, October and November. The permeability of cytoplasmatic membranes was estimated based on electrolyte leakage from leaf discs at 20°C in relation to total electrolytes in the tissue after unfreezing. The first days with temperature drops down to around 0°C in autumn resulted in a decrease in chlorophyll a, b and carotenoid content, but significantly increased anthocyanin content. The ratio of chlorophyll a to b and the ratio of total chlorophylls to carotenoids did not change in particular months. In both years of study, similar changes in dry matter content of the <i>Waldsteinia</i> leaves were observed. Dry matter content significantly increased in June and November and decreased in May and October. In June and in autumn, after first slight frosts, an increase of electrolyte leakage from the leaf discs was observed. However, high dry matter content (40.3%) was accompanied by lower permeability of the cytoplasmatic membranes of the leaves after winter during March. These results have shown good adaptation of <i>Waldsteinia trifolia</i> plants to the climatic conditions in Poland.

Dormancy and sprouting in onion (Allium cepa L.) bulbs. I. Changes in carbohydrate metabolism

SummaryDormancy and sprouting were studied in two onion cultivars with a clear period of dormancy using a large number of replicates, and single-bulb sampling. Dormancy was evaluated on the basis of sprout leaf elongation. Changes in respiratory activity, ATP and ADP content, sucrose synthase activity, dry matter (DM) content, and the contents of glucose, fructose, sucrose, fructan, and water-soluble carbohydrates (WSC), were determined in sprout leaves, stem plate and bulb scales at weekly intervals. During dormancy, and before sprouting, changes in DM contents and various WSC in different bulb parts suggested mobilisation and translocation of WSC. After a period of dormancy, the sucrose synthase activity and respiratory activity in the centre of the bulb increased, concomitant with initial sprout growth. The demonstrated separation between dormancy and the sprouting period in these cultivars should provide a good starting point for comprehensive studies on dormancy regulation in onion bulbs.

Optimising harvest timing by predicting dry matter content of whole-crop cereals for silage

Abstract Timing of harvest is the single most important factor affecting the yield and quality of whole-crop cereals used for conserved feed. Changes in dry matter content (%DM) and relationships to herbage quality and maturation are presented for experiments conducted over three seasons beginning in 2001/ 2002. Changes in crop characteristics such as ear moisture, ear fresh weight, ear dry weight and leaf fraction were monitored to determine whether growers could use crop-based measurements in place of whole-crop % DM content to assist withdecision making close to harvest. A preliminary model defined the rate of crop maturation for a range of currently grown cultivars. Linear patterns of dry down occurred with only small variation in drying rate for the duration of grain filling. A model with specific inputs for cultivar, date of awn tip appearance (GS49), and developmental response to thermal time formed the basis of a decision support tool that enables growers and contractors to predict optimum harvest timing for whole-crop cereals. Keywords: silage maturity, supplements, forage, herbage quality

Effect of various bale treatments on physical quality and chemical composition of rhodes grass (Chloris gayana) hay

The effect of harvest season (winter vs. summer), moisture content at baling and bale mass on hay physical quality and chemical composition of two varieties of Rhodes grass (Chloris gayana) was studied during bale storage. Three moisture levels (15–20%, 20–25%, 25–30%) and three bale masses (13 kg, 18 kg, 24 kg, at an equal volume) were tested in varieties Pioneer and Alimba ‐ the most common cultivars in the Arabian Gulf region. Variety Alimba has a rougher texture with more stems and fewer leaves. This caused significantly higher water retention and consequently higher bale temperatures. In summer, bale temperatures of Alimba stored at 25–30% moisture content and 24 kg bale mass averaged 37.7°C compared with 28·2°C in variety Pioneer. Lowest dry‐matter (DM) content was 793 g kg−1 and was recorded in the winter cut of variety Alimba baled at the upper moisture level (25–30%), whereas the highest was that of variety Pioneer. Lowest crude protein content was that of variety Pioneer (61 g kg DM−1). Prolonged heat build‐up of some bales caused dark‐brown discoloration, and, although colour variations were significant, they were not large. There was no contribution of bale mass to changes in DM content, indicating that the selected levels of bale mass in the experiment were lower than those expected to cause significant effects on hay chemical composition and nutritive value. In general, it is recommended to store Rhodes grass hay at moistures up to 30% and even higher in the summer season in the case of variety Alimba. Higher moisture contents at baling could preserve hay quality by minimizing shattering of leaves excessively dried under the prevailing hay‐making conditions, especially in the variety Pioneer.

Changes in the structure and function of the epaxial muscle of rainbow trout ( Oncorhynchus mykiss) in relation to ration and age : III. Chemical composition

The chemical composition of white and red muscle has been studied in rainbow trout in relation to age and ration level (RL), together with the deposition and mobilization of fat from the three main adipose tissues (viscera, dorsal and abdominal wall). Protein in red and white muscle increased with age up to 1.4 years and remained practically constant from then on, irrespective of ration level. In all tissues studied, fat content increased with age until a final steady level was reached, dependent on ration level and tissue. In white muscle and viscera, however, this increase was preceded by a decrease in fat content (0.3–1.1 years). Subjecting fish to a new RL resulted in a change in the fat content to the same level as that in fish fed at this RL from the start. The total amount of fat was regulated in all tissues, except visceral adipose tissue, by altering the relative fat content rather than by increasing or decreasing the relative size of the tissue. Overall changes in dry matter content, from hatching to sexual maturation, correlated mainly with protein in white and with fat in red muscle. However, when young and older fish were studied separately it became apparent that a change in protein content was closely related to changes in dry matter in both muscle types early in life (fish < 1.1 years) and fat later on (> 1.1 years). The glycogen level varied in parallel in red and white muscle, except for the large increase in white versus red muscle after the glycogen depletion in connection with saltwater transfer. Subjecting fish to a new RL caused rapid changes in glycogen content in young specimens. Underfed fish produced markedly elevated levels of muscle glycogen. Season, sex or sexual maturation had no effect on the chemical composition of the muscle.

The effects of radiation and extended storage on the chemical quality of garlic bulbs

Several chemical parameters were investigated in ‘red’ variety garlic, irradiated to inhibit sprouting, with doses of 30 Gy and kept under warehouse conditions. The studies were conducted between 210 and 270 days post harvest (critical marketing periods) when this variety was not normally available for raw consumption. It was found that, during storage, the irradiated garlic showed a significant increase in ascorbic acid content but no change in dry matter content compared with non-irradiated garlic. Compared with non-irradiated garlic, at 270 days' storage, the irradiated garlic had a higher index of flavour, measured as enzymatic pyruvate, a higher acidity and a lower content of water-soluble carbohydrates. From these observations, the irradiated garlic should be suitable for prolonged storage with the object of marketing it during critical periods.

A Definition of Optimum Nutrient Requirements in Birch Seedlings

AbstractBirch seedlings (Betula verrucosa Enrh.) were grown in nutrient solutions with pH varied in the range 2.5 to 6.8 or temperature varied in the range 2.5 to 35°C. The criteria for maximum growth previously established for birch seedlings were used and maintained by means of automatic pH and conductivity titrations with stock solutions containing the optimum nutrient proportions. Both nitrogen sources, NH4 and NO3, were present in the solutions. Growth rate was maximum or close to maximum between pH 4.0 and 6.8, whether kept at a specific level or allowed to vary between the extremes. At pH 3.5 and lower, the calcium uptake was decreased and root damage was observed. The seedlings has also a high dry matter content and obviously an unsatisfactory water balance. pH 2.5 was rapidly lethal. Growth rate was linearly correlated with solution temperature up to 20°C. Temperatures above 30°C, especially in the range 32.5 to 35°C, resulted in rapid decrease in growth rate. The nutrient contents in the seedlings were strongly affected by solution temperature in the low as well as in the high range when expressed on a dry weight basis. However, this effect was almost entirely attributable to changes in dry matter content. When expressed on a fresh weight basis, nutrient uptake and nutrient status of the seedlings appeared to be optimum throughout, although a variation remained since the varying dry matter content is included in the fresh weight basis. The results indicate, in agreement with the literature, that disturbed water uptake and water balance is the way in which growth is affected by root medium temperature. Similarly, extremely low pH levels in the nutrient solution meant root damage, although birch seedlings appear comparatively insensitive to pH variations. Thus, the growth technique used supplied the seedlings with adequate nutrients, so that the criteria used in the definition of nutrient requirements in birch seedlings are valid within wide ranges of solution pH and temperature; and other factors than nutrition determine growth.