Percent Decay Research Articles

Effect of composite edible coatings and modified atmospheric packaging on physical quality characteristics of ber (Ziziphus mauritiana Lamk.) cv. Umran

Ber (Ziziphus mauritiana Lamk.) is an indigenous and economically important tropical fruit which is also known as Indian jujube, and belongs to the family Rhamnaceae. The major constraint for the market glut is the shelf life of ber fruit which is only 4 to 5 days. Due to the short shelf life of ber fruit, there is a need for proper preservation methods to enhance the shelf life. Methods to increase its shelf life by applying different surface coating treatments were developed to regulate the market for fresh fruit. Evaluation of a composite edible coating made of Aloe vera gel was scheduled along with modified atmospheric packaging to enhance the shelf life and maintain the quality of the ber cv. Umran. The physical characteristics of fruits were analyzed and recorded at four days intervals when kept at ambient conditions of 22-25 °C. The study revealed that during 16 days Aloe vera gel coatings proved beneficial in preserving the quality of ber fruit stored in modified polyethylene bags. The lowest Physiological loss in weight (PLW) %, percent decay, and shrinkage while the highest holding in weight and diameter of fruits were found in Aloe vera gel (75%) coatings integrated with 1% ascorbic acid and 1% citric acid as an antioxidant. According to the findings, it is concluded that Aloe vera gel based edible coatings incorporated with 1% ascorbic acid, duly packed in polyethylene bags and kept at ambient conditions were proved to best combinations and could be used to maintain the quality of ber fruits until 16 days.

Utilization of Aloe vera gel and Acalypha indica. L leaf extract as edible coating to increase the shelf life of guava (Psidium guajava. L) fruit

The technology that is commonly used to control postharvest pathogen attacks is coating with synthetic chemicals, but this has an unfriendly impact on the environment and consumers. Coating with A. vera L gel and plant extracts is a natural way to extend shelf life and maintain postharvest quality. The research was focused on finding the composition of guava fruit coating with A. vera. L gel and A. indica. L leaf extract that provided physicochemical properties with optimal quality during storage. Parameters tested were weight loss, percent decay, moisture content, total dissolved solids and total titrated acid from guava fruit. The coating composition that gives the best guava fruit quality with a storage time of 15 days were 85% A. vera gel, 10% A. indica. L leaf extract, 0.025% Carboxy Methyl Cellulose (CMC) and 0.5% glycerol. The guava fruit coated with this composition had a weight loss of 11.19%, moisture content of 57.15%, a spoilage of 3.33%, a total dissolved solids of 7.67 oBrix and a total titrated acid of 1.90%. This value was better than uncoated fruit with weight loss of 30.48%, moisture content 28.42%, spoilage 14.44%, total dissolved solids 12.33 oBrix and total titrated acid 0.40%.

Shelf life and quality of tomato (Lycopersicon esculentum Mill.) fruits as affected by neem leaf extract dipping and beeswax coating

ABSTRACT The effect of Beeswax (BW) coating and Neem leaf extract (NLE) dipping on the shelf life of tomatoes (Lycopersicon esculentum Mill.) was investigated over a storage period of 36 days. The experiment was done by a factorial combination of four levels of NLE dipping (0, 15%, 20% and 25%) and BW coating (0, 3%, 6% and 9%) in randomized complete block design with three replications. It was observed that BW9*NLE25 significantly (P < .001) extended the shelf life of tomato fruits by eight days and effectively reduced weight loss by 55–68%, the changes in TA by 20–66.7%, PH by 6.3–14.1%, and TSS by 2.8–6.9%. Toward the end of the storage period (on the 28th day), BW9*NLE25 found to have 39.4% higher marketable fruits while reducing the percent decay by 96.1% compared to untreated tomato fruits. The study result showed that BW9*NLE25 could potentially be utilized to extend the shelf life and maintain the quality of tomato fruits by farmers, retailers, and wholesalers.

Incidence of Internal Decay in American Elms (Ulmus americana) Under Regular Fungicide Injection to Manage Dutch Elm Disease

Fungicide injection is regularly performed to prevent and manage Dutch elm disease (DED) of American elm (Ulmus americana). In an effort to better understand the effects of long-term fungicide injection on tree health, sonic tomography (SoT) and electrical-resistance tomography (ERT) were used to nondestructively determine the incidence and severity of internal decay in the lower trunk of American elms in suburban and urban settings. Overall, 253 sonic and electrical-resistance tomograms were generated from 210 American elms. Sampled trees were partitioned into two fungicide injection groups: (1) regular injection; and (2) irregular injection or no known history of injection. Among all American elms, the incidence of internal decay in the lower trunk was 30% (63/210) with a mean percent decay, as determined by SoT, of 39%. Based on Chi-square analysis, there were no significant differences in the frequency of elms with decay by injection history (P = 0.799). Mean percent decay was significantly different by dbh class (P = 0.005) and while linear regression demonstrated a positive correlation between percent decay and dbh, most of the variability went unexplained (R2 = 0.182). For elms with decay, there was a significantly higher frequency of trees in the lowest decay class (&lt; 25% of the cross section) compared to the highest decay class (&gt; 75% of the cross section). The results suggest that the wounding associated with regular fungicide injection does not increase the likelihood of internal decay and that American elms exhibit a low frequency and severity of internal decay.

Cultural, Chemical, and Alternative Control Strategies for Rhizopus Soft Rot of Sweetpotato.

Rhizopus soft rot, caused primarily by Rhizopus stolonifer, is one of the most common postharvest diseases of sweetpotato and is often considered the most devastating. Traditionally, Rhizopus soft rot has been effectively controlled using postharvest dips in dicloran fungicides; however, due to changes in market preferences, use of these fungicides is now limited. This, along with the lack of labeled and effective fungicides for control of Rhizopus soft rot in sweetpotato, creates the need for integrated strategies to control the disease. The effects of storage temperature (13, 23, and 29°C), relative humidity (80, 90, and 100%), and initial inoculum levels (3-, 5-, and 7-mm-diameter mycelial plugs) on progression of Rhizopus soft rot in 'Covington' sweetpotato were examined. Percent decay due to Rhizopus soft rot infection was significantly reduced (P < 0.0001) at a low temperature (13°C) but was not significantly affected by changes in relative humidity or initial inoculum level (P >0.05). Sporulation of R. stolonifer was also significantly reduced at the lowest temperature of 13°C. High relative humidity (>95%) significantly increased sporulation of R. stolonifer and sporulation also increased as initial inoculum level increased. Efficacy of chlorine dioxide (ClO2) fumigation, UV-C irradiation, and postharvest dips in alternative control products were also investigated for control of Rhizopus soft rot. Static ClO2 treatments were effective in reducing sporulation on treated roots but had no significant impact on incidence of Rhizopus soft rot. UV irradiation at 3.24 KJ/m2 1 h after inoculation as well as dips in aqueous ClO2 and StorOx 2.0 significantly (P < 0.05) reduced disease incidence. Understanding the epidemiological factors favoring Rhizopus soft rot and identifying alternative control strategies allow for improved recommendations to limit postharvest losses in sweetpotato.

Teaching Hands-on Urban Forestry Health Assessment Using the Resistograph and the CTLA Method

Undergraduate students were instructed how to assess the health of 24 urban willow oak trees. Students received hands-on training using the Resistograph 400 on two sites: a depressional site and a well-drained site on the campus of Stephen F. Austin State University in an upper division Urban Forestry course. Students followed the instructed and prescribed method of drilling three holes at 120 degree intervals at 3.5 feet in height above ground in each oak tree. Tree condition data were recorded on paper strips and analyzed in laboratory for percent decay measured for each sample. The results were averaged for the three samples per tree and the percent of soundwood was determined. Resistograph data were then analyzed by the students using SAS ANOVA for the 24 trees within the two sites. Results indicted a significantly higher amount of decay on the depressional sites compared to the well-drained sites. Data collected using the standard CTLA tree health assessment method indicated willow oaks in depressional sites had a significantly lower condition rating based on six measured tree variables. This study demonstrated that incorporating intensive hands-on instruction within an undergraduate student’s education increases retention rates, enhances their educational experience, and produces a more well-rounded urban forester.

Density Separation, Storage, Shelf Life, and Sensory Evaluation of 'Fry' Muscadine Grapes

Muscadine grapes (Vitis rotundifolia Michx.), native to the southeastern United States, have a distinct flavor, and grocers are interested in marketing them as table grapes. Two studies using 'Fry' muscadines were conducted to assist the muscadine industry in providing quality table grapes. Study 1 (1998 and 1999) evaluated density sorting and relationships between maturity, color, soluble solids, firmness, shelf life, and sensory evaluation of grapes. Study 2 (1998) determined the effect of storage on quality attributes of different maturities of grapes and evaluated use of polyethylene bags to extend their storage. Density separation successfully sorted grapes by maturity. Muscadine berry color may allow for visual or electronic sorting to eliminate immature fruit. Sensory panelists could distinguish differences in maturities for all sensory attributes. In 1999 maturities 3 and 4 (≈24-33 soluble solids: acid ratio) were preferred overall by panelists. As maturity increased, soluble solids and pH increased, and acidity decreased. Firmness decreased as maturity and storage at 2 °C increased. Percent decay increased with maturity and storage time. Grapes stored in polyethylene bags had reduced decay. A chart developed from the 1999 data related berry color to soluble solids: acid ratio, soluble solids, tartaric acid, and pH. Data from these studies can be used by industry to establish harvest parameters and enhance marketability of 'Fry' muscadine grapes.

Control of silver scurf disease in stored potato by using hydrogen peroxide plus (HPP)

The present study showed that it is possible to control the silver scurf disease caused by the fungus Helminthosporium solani Durieu and Mont. in stored potato ( Solanum tuberosum) by fogging the storage rooms with 10% hydrogen peroxide plus (HPP). The percentage of infected tubers after 6 months of storage, following five treatments, was 2% compared with 38% in the non-treated control. Percent decay after a single treatment with 10% HPP 6 months post harvest was 16%. Furthermore, treatment with HPP controlled the growth of the fungus on the skin of infected harvested tubers.

Fogging disinfectants inside storage rooms against pathogens of potatoes and sweet potatoes

Sweet potatoes [ Impomoea batatas (L.) Lam], cv. ‘Georgia Jet’ can be showed for 5 months by disinfecting the roots inside the storage rooms by means of fogging with 1% iprodione (a systemic fungicide), applied with the Tabor Atomizing System combined with the curing procedure. The percent decay after 5 months of storage, which followed this combined treatment, was 5%, compared with 61% in the non-treated control. The percentage of potato ( Solanum tuberosum) decay caused by Erwinia carotovora subspecies carotovora after 5 months of storage, following disinfecting the tubers by fogging the storage rooms with Compound P via the Tabor Atomizing System, was 4%, compared with 26% in the non-treated control.

Effect of toluene diisocyanate index on morphology and physical properties of flexible slabstock polyurethane foams

The effect of toluene diisocyanate (TDI) index on the physical properties, structure, and morphology of flexible slabstock polyurethane foams was investigated. Foams based on a 2700 molecular weight triol, 6 pph water, and varying amounts of an 80/20 mixture of 2,4- and 2,6-TDIs were characterized using a number of physical property and morphological measurements. Extraction experiments using dimethyl formamide (DMF) showed that increasing the index increased the level of covalent crosslinking with perhaps a maximum being reached at an index ca. 100. Viscoelastic measurements also supported the claim of increased crosslinking with TDI index. The initial load in load relaxation experiments at 65% strain systematically increased with increasing TDI while the percent decay in a 3-h period decreased. Temperature and/or humidity “plasticized” the load relaxation behavior in all the foams studied, indicating that the hard segment domain physical “crosslinks” play a significant role in the properties of these materials. Interestingly, compression set measurements appeared to be independent of the index, likely due to some level of hard segment continuity, but the induced recovery of the compression set at elevated temperatures was indeed sensitive to the index. The amount of recovery systematically increased with increasing TDI index due to the more enhanced “recoverable” covalent network. Scanning electron microscopy (SEM) studies of the foams showed that the cellular structure was not significantly affected by the index. However, SEM also showed that the structure of the high index foam was not greatly altered by the extraction process while the lowest index foam's cellular structure was severely disfigured. The fine structure of the foams was found to be influenced by the TDI index. Small angle X-ray scattering, differential scanning calorimetry, and dynamic mechanical analysis all provided evidence that an increase in the TDI index promoted some phase mixing of the soft and hard segments. FTIR showed that the short-range ordering within the hard segment domains displayed a maximum at an index of 100. This was attributed to the concentration of hard segment domains being lower at a lower index and their ordering being disrupted at higher indexes due to more extensive covalent crosslinking prior to completion of phase separation. Wide angle X-ray scattering results also confirmed that for the highest index level, the short-range ordering of the TDI moieties was decreased. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2395–2408, 1997

Effects of Harvesting Practices on Damage to Florida Grapefruit and Oranges

A series of tests were conducted to assess damage of field harvesting and handling practices to fresh citrus. Respiration, weight loss, percent decay, and a dye score, related to abrasive damage, were measured. The respiration level and dye scores were monitored at various handling points while the weight loss and decay were evaluated for an overall handling procedure. Concurrent research was conducted with an instrumented sphere (IS) to measure impact points in harvest operations of fruit removal, bagging, and transfer to pallet bins. The most conclusive indicator of damage was the dye score which ranged from 1.1 (four-point visual scale) for hand-picked control samples to 2.4 for samples dropped to the ground, subsequently gathered and placed in pallet bins, and transported to a packinghouse.

146 STORABILITY OF APPLES DAMAGED BY TUFTED APPLE BUD MOTH

In the 1992-93 experiments tufted apple bud moth (TABM) damage generally had little effect on at-harvest maturity/quality indices of `Golden Delicious', `Delicious' or `York Imperial' apples. However, at harvest starch scores of `Golden Delicious' and the soluble solids (SS) of `York Imperial' were higher in fruit with TABM damage. Following storage however, there were little or no effects of TABM damage on firmness or SS in any of the 3 cultivars. Percent decay was 0 and 18% in `Golden Delicious' and 2 and 6% in `Delicious' for control fruit and those with the most TABM damage (&gt; 10 mm aggregate diameter), respectively. These were significant linear relationships - R2 = 0.41 and 0.12 for `Golden Delicious' and `Delicious', respectively. Weight loss increased by 2-3 fold in the apples in the highest damage category. These results show that the post-storage quality of apples with slight TABM damage did not differ from that of undamaged fruit. Good CA atmospheres for storage of undamaged fruit were also good for storage of damaged fruit. Additional studies done in 1993-94 included experiments attempting to mimic TABM damage artificially on fruit while still on the trees. Apples with natural TABM damage were inoculated with P. expansum before storage to insure decay potential.

702 PB 318 SHELF-LIFE AND PHYSIOCHEMICAL PROPERTIES OF HIGHBUSH (VACCINIUM CORYMBOSLM) AND RABBITEY E-(V. ASHEI) BLUEBERRIES FOR FRESH MARKET

Three varieties of rabbit eye (Vaccinium ashei) blueberries (`Climax',, `Premier', and `Tifblue') were harvested in Mississippi and two varieties of highbush (v. corymbosum blueberries (`BlueCrop' and `Jersey') were harvested in Michigan. Each variety was harvested at three different locations as replications. The berries were rapidly cooled to 5°C after harvest, placed in 1-pint containers, and analyzed at 7-day intervals for 28 days with day 0 being 48 h after harvest. Shear, compression and puncture forces were higher for rabbiteye spp. than for highbush spp. `Bluecrop' blueberries showed the lowest shear force whereas, Climax, had the most shear force. Puncture force (skin toughness) was lower for `Bluecrop' and `Jersey' and higher for, Climax, There was an increase in shear force by all varieties with storage time. `Premier, and `Climax' had lower soluble solids, but they increased with storage time. `Jersey' had the highest pH and `Tifblue' the lowest. Although all varieties lost moisture with time, `Bluecrop' always had higher moisture. Mold growth varied with time; however, `Bluecrop' had a higher percentage of moldy berries throughout refrigeration. The percent decay was higher for highbush blueberries after 16 d of refrigeration. Rabbiteye's toughness and firmness give them a longer refrigerated shelf-life over highbush blueberries.

Percent decay estimation using decayed wood area at breast or stump height

The estimation of tree percent decay is important for estimating the quantity and quality of wood available for timber products. Several different independent variables have been used to estimate the percent decay of standing trees, but often the resulting percent decay predictions are poor. Other independent variables are required for more precise prediction of percent decay. The objective of this study was to examine the use of percent decay area measured at breast or stump height as a possible variable for estimating tree percent decay. Data used in testing included one species group, true fir (Abies spp.), and two species, western red cedar (Thujaplicata Donn) and trembling aspen (Populustremuloides Michx.), from several zones of the province of British Columbia. The use of percent decay area at either breast or stump height resulted in substantial improvements in the estimation of percent decay for all species in all zones. As an alternative to the expensive task of measuring percent decay area on all trees, a sampling design is suggested and one possible design is illustrated.

Using limited dependent variable estimators for estimating percent decay

The data used for the estimation of percent decay are bounded by zero and 100. Because a value of 100% indicates that the tree is completely decayed, this value is not observable in nature. However, a value of zero percent is often observed over a wide range of the independent variables. The distribution of percent decay is a combination of a truncated continuous distribution for percent decay greater than zero and a discrete component for the zero percents. The use of ordinary least squares with this type of data results in biased and inconsistent estimates of the coefficients of a percent decay equation. An alternative is the tobit estimator (a combined regression and probit estimator based on a maximum likelihood equation), which results in consistent estimates of the coefficients if the error terms of the model are independent and identically distributed as the truncated normal distribution. A Monte Carlo simulation using data for three species with different proportions of zero percents was performed to compare the ordinary least squares and tobit estimators. As expected, the tobit estimator resulted in quite different estimates of the coefficients of the equations than did ordinary least squares. An unexpected result was that the estimated expected percent decay was slightly more biased for the tobit estimator than for the ordinary least squares estimator, even with a large number of zero percents in the data set. Possible explanations for the Monte Carlo simulation results and recommendations for fitting percent decay equations are given in the paper.

Spontaneous decay of oxidized ascorbic acid (dehydro-L-ascorbic acid) evaluated by high-pressure liquid chromatography

We applied high-pressure liquid chromatography to assess the decomposition of the oxidized form of vitamin C, dehydro-L-ascorbic acid. We selected experimental conditions that might represent a wide variety of clinical and research procedures. Decay of dehydro-L-ascorbic acid proceeded much more rapidly at high pH (7-8) than at low pH (3-5) and was more rapid at 37 or 45 degrees C than at 0 or 23 degrees C. When evaluated at pH 6.6, the percent decay was somewhat more rapid from an initial concentration of 1000 mumol/L than at 5-10 mumol/L. The analytical procedure (HPLC) provided useful information about the rate of decay under various conditions. This may facilitate future biological and clinical studies that require a distinction between the oxidized and reduced forms of vitamin C.

Individual Seal-packaging Enables the Use of Curing at High Temperatures to Reduce Decay and Heal Injury of Citrus Fruits

Abstract The marked extension of life of citrus fruit by individual seal-packaging has attracted both basic and commercial interest (5). Delayed physiological deterioration by seal packaging was related to the alleviation of water stress of the harvested fruit (10). A risk from this technique is the possibility that decay might be enhanced by the water-saturated atmosphere of the sealed fruit (5). Although most reports do not describe any marked effect on decay, several noted that the percent decay of ‘Shamouti’ and ‘Valencia’ oranges was lightly increased by seal-packaging (5). This increase could be a function of time, since the storage life of sealed fruit is longer than that of nonsealed fruit (5, 20). Sealing of citrus fruit increased stem-end rot in general and Alternaria rot in particular (5). However, this type of decay usually requires 8 weeks for incubation, longer than fruit are usually kept in sealed packages. The major pathogen causing decay of citrus is still the green mold Penicillium digitatum Sacc. (20).

Evaluation of Chlorophyll Fluorescence Parameters for an Intact‐Plant Herbicide Bioassay1

The correlations between various chlorophyll fluorescence induction curve parameters and metribuzin [4‐Amino‐6‐(1,1‐dimethyl‐ethyl)‐3‐(methylthio)‐1,2,4‐triazin‐5(4/H)‐one], diuron [3‐(3,4‐Dichlorophenyl)‐1,1‐dimethylurea], and atrazine (2‐chloro‐4‐ethylamino‐6‐ isopropylamino‐S‐triazine) concentrations were compared in laboratory studies. The ratio of the initial inflection point (I) to the initial peak (P) was the most precise indicator of photosynthetic inhibition over time intervals of 4 to 48 h after an oat (Avena sativa L. ‘Chilocco’) plant was transplanted into herbicide‐treated soil. The height of the initial inflection point (I), the peak level (P), and the fluorescence level 30 s after the onset of illumination (T) were also useful at 4 and 8 h after transplanting, but correlated poorly with herbicide concentration at later time intervals. Other variables examined included the slopes from I to P and P to S, the percent decay from P to T, and the complementary area. These parameters did not correlate to herbicide concentration as well, and had a much higher degree of variability associated with them.

Effects of Laminated Root Rot on Relationships Between Stem Growth and Root-System Size, Morphology, and Spatial Distribution in Douglas-fir

Abstract Root-system size (length, cross-sectional area, and volume) was measured in 30- to 40-year-old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) in five stands. Mean root-system size varied widely among stands (length 2,485-5,316 cm; cross-sectional area 4,070-13,520 cm²; volume 72,760-251,020 cm³). Percentage of roots decayed by Phellinus weirii varied among stands and among root orders ranging 22-83 percent by length and 21-84 percent by volume. Root size distribution in P. weirii-infected trees was generally of the same magnitude and pattern as in healthy trees. Diameter at breast height (dbh) was highly correlated with total root-system size in all stands in all three root measures. Height was highly correlated with total root-system size in four stands. Diameter at breast height increment and dbh increment percent and height-dbh ratio were moderately correlated with root-system size in some stands and for some root measures. Height increment percent was poorly correlated with root-system size. Correlations of most stem variables with sizes or percent decay of roots stratified by root orders and by distance and depth zones were significantly stronger than correlations with total root-system size. Healthy and infected trees differed in the root orders and zones that were most strongly correlated with stem-growth variables. Diameter at breast height and height were mostly positively correlated with infected and healthy root sizes whereas increment variables were predominantly inversely correlated with infected root size. Stem radii measured vertically above junctions of infected roots with the stem base were smaller than those measured above junctions of healthy roots. Radial increments above infected roots producing adventitious branches were greater than those above other infected roots or above healthy roots. Forest Sci. 32:202-219.

Physical and Chemical Changes in Muscadine Grapes During Postharvest Storage

Commercially harvested muscadine grapes were stored at 20°C, 4.5°C and 0°C to determine the biochemical parameters that may change during storage. These included percent decay, soluble solids, titratable acids, firmness, pectins, total phenols, organic acids, sugars and water loss. Decay increased rapidly in fruit stored at the higher temperatures. Percent soluble solids, percent titratable acidity, individual sugars and organic acids did not change during storage at three temperatures tested. Total phenol content increased while pectin content decreased during storage with the higher storage temperature showing greater changes.