Postharvest Storage Duration Research Articles

Impact of Storage on Nondestructive Detectability of Codling Moth Infestation in Apples

Highlights Codling moth responds differently to low temperature conditions during the supply chain. The length of storage and temperature determine the sensitivity of the codling moth to detection. Hyperspectral imaging sensor detectability of codling moth increased with temperature. Abstract. Different conditions during cold storage of codling moth (CM)-infested apples lead to different infestation levels, which affect overall product quality. In this study, the effects of postharvest storage duration (up to 20 weeks) and temperature (0°C, 4°C, and 10°C) on the detectability of CM-infested apples were investigated using the near-infrared (NIR) hyperspectral imaging (HSI) method (900–1700 nm). Fresh organic Gala apples were obtained directly from a commercial market and stored in a controlled environmental chamber at three temperatures for 20 weeks in two groups: control and CM-infested samples. Every four weeks, NIR hyperspectral images in reflectance mode were acquired directly for each set of samples. Machine learning models for the classification of CM-infested apples were developed based on the HSI data. The results revealed that storage duration and temperature had a significant effect on the performance of the classification models in the detection of CM-infested and control apples. Overall, the best classification rates were obtained for apples stored for 16 weeks, with accuracies of 97%, 94%, and 100% at storage temperatures of 0°C, 4°C, and 10°C, respectively. This study is critical for determining the effectiveness of HSI as a nondestructive method for sorting apples into classes based on CM infestation when stored under different conditions and duration, as in this study. Keywords: Apples, Codling moth, Detectability, Machine learning, Nondestructive method.

Cultivar and Postharvest Storage Duration Influence Fruit Quality, Nutritional and Phytochemical Profiles of Soilless-Grown Cantaloupe and Honeydew Melons.

There is an increasing demand for sweet melon (Cucumis melo L.) fruit in fruit and vegetable markets due to its nutritional content, resulting in different cultivars being grown in different production systems. This study evaluated the nutritional and phytochemical contents of soilless-grown cantaloupe and honeydew sweet melon cultivars at harvest and postharvest. At harvest, vitamin C and β-carotene concentrations were higher in orange-fleshed (cantaloupe) cvs. Magritte, Divine, Majestic, Cyclone, MAB 79001, E25F.00185, E25F.00075 and Adore, compared to green-fleshed (honeydew) cvs. Honey Brew and Honey Star. The zinc (Zn), phosphorus (P), potassium (K), magnesium (Mg) and calcium (Ca) contents were higher in orange-fleshed compared to green-fleshed cultivars. Total phenolics content (TPC) in cv. E25F.00075 was the highest (2.87 mg GAE∙g−1 dry weight). A significant, positive, correlation occurred between β-carotene and Zn, P, K, Ca and Mg contents. Postharvest storage duration affected TPC and total soluble solid content. The interaction of cultivar and postharvest storage duration affected flavonoid, vitamin C and β-carotene contents, free radical scavenging activity and fruit juice pH. Vitamin C and β-carotene contents decreased with increased postharvest storage duration while flavonoid content increased. The cantaloupe cultivars performed significantly better compared to the honeydew cultivars as evident in their high mineral element content, and vitamin C and β-carotene concentrations. Selection of appropriate cultivars in a production system should consider variation in nutritional traits of cultivars and postharvest storage duration. Soilless production of sweet melon cultivars in tunnels offers a viable alternative to open field to produce high-quality melons at harvest and postharvest.

The effects of pH, salinity, age of leaves, post-harvest storage duration, and psyllid infestation on nutritional qualities of giant leucaena fodder

Giant leucaena (Leucaena leucocephala subsp. glabrata) can be managed as a profusely branched bushy plant by repeated harvest of its foliage for use as fodder. The objective of this research was to determine the effects of soil pH and salinity, age of the leaves, post-harvest storage duration, and psyllid infection on the nutritional qualities of leucaena fodder. To determine the effects of soil pH and salinity on fodder quality, giant leucaena K636 plants were grown in large pots containing soils adjusted to different pH and salinity levels. The effects of age of the leaves, post-harvest storage duration and psyllid infection on fodder quality were studied using leucaena samples collected from Waimanalo Research Station. Among five pH levels tested, pH 6.0 was found to produce the highest amounts of protein and structural fibers in the foliage. Mimosine contents were highest at pH 6 and 7 and lowest at pH 5.0. The growth of giant leucaena was retarded and the nutritional quality were adversely affected under salinity conditions. Compared to young leaves, old leaves contained 18.5% less protein, 95% less mimosine, 30% less tannin and 40% more structural fibers. Post-harvest storage duration up to 72 h, at room temperature did not seem to affect protein, tannin and structural fiber contents of the foliage; however, mimosine content was reduced by 25%. These results will help to identify ideal soil pH, age of foliage, and post-harvest storage duration for obtaining high forage yield and nutritional quality for giant leucaena.

Nitrogen levels, plant density and postharvest storage duration affect phytochemical and antioxidant properties of field-grown basil and rocket crops

ABSTRACT Growers usually apply elevated nitrogen levels when plants are established at high densities to obtain improved yields. It is not known how this practice affects phytochemical and antioxidant properties of basil (Ocimum basilicum L.) and rocket [Diplotaxis tenuifolia (L.) DC]) during postharvest storage, which are important quality aspects of these crops for human health. This study investigated effects of N application (60, 90, 120, 150, or 180 kg.ha−1), plant density (40,000; 62,500 and 93,750 plants.ha−1 for basil; 40,000; 80,000 and 133,333 plants.ha−1 for rocket), and postharvest storage duration (0, 5, 10 or 15 days) on phytochemical and antioxidant properties of basil and rocket. After harvest, leaves were packaged in biaxially oriented polypropylene (anti-mist) bags and kept at 12°C and 85% relative humidity in a cold temperature room. Nitrogen application of 120 kg.ha−1 at day 0 of storage, caused the highest accumulation of total phenolic content (TPC), flavonoid content (FC), strong free radical scavenging activity, and % antioxidant with limited effect due to plant density on basil. In rocket, application of 60 to 120 kg.ha−1 N at day 0 of storage had high TPC; FC was high at 90 to 180 kg.ha−1 N and 10 days of storage. Rocket had strong scavenging activity, as a result of 120 to 180 kg.ha−1 N, at 15 days of storage, and for 60 and 90 kg.ha−1 N at 0 and 10 days of storage. Postharvest quality of basil was affected by storage time and N application; TPC, FC, and free radical scavenging activity (FRS) were reduced as storage time lengthened. Rocket had improved postharvest quality at 10 days of storage. Spacing had limited effect on all parameters in basil and rocket. The most economic treatment in basil was 60 kg.ha−1 N for TPC, FC, FRS, and antioxidant activity; in rocket, it was 120 kg.ha−1 with longer shelf-life of 10 days of storage with regard to antioxidant activity. Optimization of agronomic practises for improved production should consider phytochemical quality assurance to ensure crop health benefits to consumers are not compromised.

Effect of storage temperature and maturity stage on the postharvest period of ‘Horvin’ plums (Prunus domestica L.)

Plums are classified as a climacteric fruit with a high respiration rate between the end of their development and the start of the ripening process, thus making it necessary to apply techniques to preserve the organoleptic characteristics required for the product to have good market acceptance. The aim of this study was to evaluate the effect of harvest maturity (states 2, 3, 4, and 5) and storage temperature (2, 4, and 18 °C) on the organoleptic and physicochemical quality and postharvest storage duration of ‘Horvin’ plums. The experimental design was completely randomized with a 4 x 3 factorial arrangement. The first factor corresponded to the stage of maturity, and the second one to refrigeration temperatures, for a total of 12 treatments. Every three or four days, fruit peel color, accumulated mass loss, respiratory intensity, firmness, pH, total titratable acidity, and total soluble solids were measured every during storage. Measurements were taken until the fruits lost their organoleptic quality. For most of the measured variables, the fruits stored at 2 °C and harvested in maturity stage 5 maintained the best postharvest quality during storage. The fruits without refrigeration only reached 10 days, while the fruits stored at 4 °C and 2 °C maintained quality of consumption for 24 and 31 days, respectively. Maturity stage 5 presented the highest values of accumulated mass loss, pH, total soluble solids, color index, maturity index, and respiratory intensity.

Determining the Effect of Postharvest Cold Storage Treatment on the Survival of Immature Drosophila suzukii (Diptera: Drosophilidae) in Small Fruits.

We evaluated the effect of postharvest cold storage temperature (0.0-2.2°C) and duration (3-5 d) on pupal emergence of single life stage populations of laboratory-generated Drosophila suzukii (Matsumura) and mixed-age populations collected in the field from blackberries, blueberries, strawberries, and raspberries. For field-infested fruit, cold storage at any temperature and duration resulted in less pupal emergence compared with the control held at 20°C, but D. suzukii subjected to higher temperatures and shorter storage durations in caneberries had higher survival. When a single life stage of D. suzukii was exposed to cold storage, pupal emergence was significantly reduced across all fruit types held at 0°C and for most life stages and fruit types held at 1.5 and 2.2°C, dependent on the substrate. Freshly laid eggs exposed to cold storage produced the lowest pupal emergence. Our results suggest using cold storage treatment is an effective postharvest management strategy for small-fruit growers to use on-farm as part of an integrated program to manage D. suzukii infestation. An economic assessment was made to examine the profit implications of an investment in cold storage units to counter pest pressure. Results suggest that investment in a cold storage unit would breakeven in about 4 yr. On farms that already have cold storage installed, we estimated a $0.11/kg decrease in blueberry market price for holding fruit for 3 d. Together, this cost assessment will provide growers with the knowledge to make decisions based on infestation risk and the seasonal sale price of blueberries.

Preserving postharvest storage quality of fresh-cut cactus pears by using different bio-materials

BackgroundCactus pear (Opuntia ficus-indica (L.) Miller) is an important food source for human beings but its consumption and marketability are limited due to the presence of spines and glochids on the fruit surface. Fresh-cut, ready-to-eat cactus pears have higher preference than the whole fruits. However, fresh-cut fruits have tissue wounding and quick deterioration, which decrease the marketability of the products. Therefore, present study was aimed to improve the storage quality of ready-to-eat cactus pears with the application of environmentally friendly bio-materials.MethodsFruits of present study were hand collected by a traditional way from a farm located in Yayla village of Northern Cyprus. Fruits were then peeled to prepare fresh-cut prickly pears for further experiments. Fruit peeling was carried out in three steps: (i) slicing off and discarding the both ends of the prickly pears, (ii) making one long vertical slice down the body, and (iii) peeling back the skin by sliping our finger into the slice and preparing a peeled prickly pear without skin. The six treatments of present study are: (1) control—dipping the fruits into distilled water, (2) covering the fruits with Vitis vinifera leaves, (3) dipping the fruits into jelly, (4) dipping the fruits into Aloe vera gel, (5) dipping the fruits into Portulaca oleracea extract and (6) dipping the fruits into cactus gel. Totally 108 fruits (replications) were used for each treatment and 18 fruits from each treatment were selected for quality analysis with 3-days interval (3, 6, 9, 12, 15 and 18 days). Fruits of each treatment (6 from same treatment) were placed into an open plastic box (dimensions: 20 * 13 * 5 cm; material: PET) and was covered with a stretch film (LLDPE, 10 µm) for storage. The fruit boxes were stored at storage rooms adjusted to 5 ± 1 °C and 55 ± 5% relative humidity.ResultsResults showed that, all treatments have varying positive effects on the prevention of weight loss. Among them, the highest positive effect was received from A. vera gel treatment (0.98%), and is followed by cactus gel (1.15%), V. vinifera leaf (1.39%) and jelly (1.61%) at the end of the experiments (18 days). A. vera gel and cactus gel were also found to have highest influence on the prevention of off-odor and decay incidence; and to protect the sensory and visual quality of the ready-to-eat cactus pears.ConclusionsResults suggested that the postharvest storage duration of ready-to-eat cactus pears might be extended from 9 to 15 days with the use of Aloe vera gel or cactus gel.

Effect of different post-harvest treatments on free amino acid content in Fucus vesiculosus

The effect of different post-harvest treatments (fresh, freezing and air-drying) and storage duration on free amino acid (FAA) content of brown seaweed Fucus vesiculosus were studied. The FAA profile of thalli algae was studied every 3 months over 1 year. The FAA were extracted in ethanol/water (70: 30) solution, purified by ion exchange chromatography, derivatized and determined using hight-performance liquid chromatography. Free amino acid profile was significantly (p<0.001) different among the fresh, freezing and air-drying seaweeds. Long-term storage of seaweeds for 12 months in both dried and frozen form contributed to increased levels of free amino acids. The total free amino acid content increased from 285.80 mg/100 g dry matter of fresh seaweeds to 597.38 mg/100 g dry matter of dried seaweeds and to 473.84 mg/100 g dry matter of the frozen form. The total content of essential amino acids increased from 49.65 mg/100 g dry matter in fresh seaweeds to 130.45 mg/100 g dry matter of dried seaweeds and to 106.70 mg/100 g dry matter of frozen seaweeds. The content of glutamic acid responsible for the taste increased from 132.36 mg/100 g dry matter of fresh seaweeds to 169.50 mg/100 g dry matter of dried seaweeds, and to 242.00 mg/100 g dry matter of frozen seaweeds. Thus, the long-term storage of dried and frozen seaweeds contributes to the improvement of their qualities.

Storage time assessment and shelf-life prediction models for postharvest Agaricus bisporus

Rapid senescence and short shelf-life of fresh Agaricus bisporus can cause serious economic losses. Sometimes even illegal additives are used to maintain the freshness of A. bisporus. This misconduct can bring health risks to consumers. Therefore, it is meaningful to establish shelf-life prediction model for taking necessary measures to reduce the losses, and establish storage time assessment model to evaluate the true postharvest storage duration of A. bisporus to prevent commercial misconduct. We developed storage time assessment model and shelf-life prediction model based on mushroom texture (hardness, gumminess, chewiness), signal of water mobility and typical flavor. With the extension of storage time, all the qualities of A. bisporus showed a decreasing tendency at different temperatures. Quality decreases were proven suitable to the first-order kinetic model. Gumminess was a more accurate index to assess how long postharvest A. bisporus has already been stored (the storage time), whereas chewiness was a more precise index to predict how long postharvest A. bisporus can be stored (the shelf-life). These mathematical models can be useful to assess the storage time and predict the shelf-life of fresh A. bisporus during distribution chain and storage under a temperature range of 4–20 °C.

The quality of baby spinach as affected by developmental stage as well as postharvest storage conditions

ABSTRACTBaby spinach is rich in phytochemicals that provide great benefits to consumers’ health. The study aim was to investigate the effect of the growth harvest stage, postharvest storage duration and temperature on quality of baby spinach leaves. A 3 × 5 × 3 factorial experiment was laid out in a randomised complete block design with four replicates per treatment. The treatments were arranged as follows namely: stage I [28 days after sowing (DAS)], stage II (35 DAS)and stage III (42 DAS), and leaves were kept up to 12 d at three different temperatures – 4, 10 and 20°C. The study demonstrated that the overall appearance and odour were both well maintained in the leaves of baby spinach harvested at stage II. The baby spinach harvested 28 DAS led to higher content of iron [1.13 mg g−1 dry weight (DW)], magnesium (14.4 mg g−1 DW), and zinc (0.17 mg g−1 DW). The highest level of total antioxidant activity (0.43 mg g−1 DW) and flavonoids (12 mg g−1 DW) after 12 d of storage was observed in baby spinach leaves at stage I when stored at 4°C. Therefore, baby spinach leaves harvested 28 DAS and store at 4°C for 6 d improved shelf life and nutraceutical quality. Thus, early harvest of fresh produced baby spinach harvested in order to attain high phytochemical and mineral content when stored at low temperature (4°C) without exceeding 6 days is recommended.

Seed quality in pumpkin (Cucurbita pepoL) cv. Punjab samrat as affected by fruit harvesting and storage duration

An experiment was conducted in 2013 to study the seed quality of pumpkin (Cucurbita pepo L.) variety Punjab Samrat as affected by stage of fruit harvest and post harvest storage duration. Fruits were harvested 25, 35 and 45 days after pollination (DAP) which were stored for 0, 10, 20 and 30 days after each date of harvesting (DAH). The number of seeds per fruit, 100 seed weight, seed weight per fruit and percentage of developed fruits were higher in fruits harvested at 45 days after pollination. Maximum germination index, germination percentage and seedling vigour indices was obtained when fruits were harvested 45 DAP and stored for 30 DAH. However the content of malondialdehyde which is an indicator of membrane damage decreased in seeds obtained from fruits harvested at alter stages and stored for longer duration. The amount of total sugars decreased while total lipids and total free amino acids increased in fruits harvested at 45 DAP and stored for 30 DAH. Germination index, germination percentage and seedling vigour indices were also maximum seeds obtained from fruits harvested 45 DAP and stored for 30 days DAH.

Influence of Postharvest Storage Temperature and Duration on Quality of Baby Spinach

Spinach (Spinacia oleracea) is a member of the Amaranthaceae family. Baby spinach leaves have a very high respiration rate, thus postharvest quality is affected mostly by tissue decay and the development of off-odors. Thus, this study was conducted to investigate the influence of storage temperature and time on the postharvest quality of baby spinach. Baby spinach leaves were harvested 36 days after planting and subsequently stored at 4 and 22 °C for 0, 2, 4, 6, 8, 10, or 12 days. Thereafter, the leaves were incubated for 72 hours at 40 °C to dry. Minerals, trace elements, total phenols, total carotenoids, flavonoids, and antioxidant activities were measured. Concentration of magnesium (Mg), zinc (Zn), and iron (Fe) were declined after 8 days of storage at 4 °C, while at 22 °C they declined after 2 days of storage. Mg, Zn, and Fe revealed a similar trend with significantly higher carotenoids found up to 6 days in storage at 4 °C, while at 22 °C the carotenoid levels declined after only 2 days. Total phenolic compounds gradually decreased in samples stored at 4 °C. However, samples stored at 22 °C showed a rapid decrease after 4 days. Both total antioxidant activities and vitamin C content showed a similar trend, with the content remaining constant at 4 °C and decreasing after 6 days, whereas the total antioxidant activities and vitamin C for leaves stored at 22 °C decreased immediately after 2 days. Results demonstrated that quality of baby spinach deteriorates as storage time and temperature increase.

Effects of Post-harvest Storage Duration and Variety on Nutrient Digestibility and Energy Content Wheat in Finishing Pigs.

This study was conducted to investigate the effects of post-harvest storage duration and wheat variety on the digestibility and energy content of new season wheat fed to finishing pigs. Two wheat varieties (Shi and Zhong) were harvested in 2013 and stored in the warehouse of the Fengning Pig Experimental Base at China Agricultural University for 3, 6, 9, or 12 mo. For each storage period, 12 barrows were placed in metabolism crates and allotted to diets containing 1 of the 2 wheat varieties in a randomized complete block design. The experimental diets contained 97.34% wheat and 2.66% of a vitamin and trace mineral premix. With an extension of storage duration from 3 mo to 12 mo, the gross energy (GE) and crude protein (CP) of the wheat decreased by 2.0% and 12.01%, respectively, while the concentration of neutral detergent fiber (NDF), acid detergent fiber (ADF) and starch content increased by 30.26%, 19.08%, and 2.46%, respectively. Total non-starch polysaccharide, total arabinose, total xylose and total mannose contents decreased by 46.27%, 45.80%, 41.71%, and 75.66%, respectively. However, there were no significant differences in the chemical composition between the two wheat varieties with the exception of ADF which was approximately 13.37% lower in Shi. With an extension of storage duration from 3 mo to 12 mo, the digestible energy (DE), metabolizable energy (ME) content and the apparent total tract digestibility of GE, CP, dry matter, organic matter, ether extract, ADF and metabolizability of energy in wheat decreased linearly (p<0.01) by 5.74%, 7.60%, 3.75%, 3.88%, 3.50%, 2.47%, 26.22%, 27.62%, and 3.94%, respectively. But the digestibility of NDF changed quadratically (p<0.01). There was an interaction between wheat variety and storage time for CP digestibility (p<0.05), such that the CP digestibility of variety Zhong was stable during 9 mo of storage, while the CP digestibility of variety Shi decreased (p<0.05). In conclusion, the GE, DE, and ME of wheat was stable during the first 3 to 6 mo of post-harvest storage, and decreased during the following 6 to 12 mo of storage under the conditions of this study.

Temporal valuation of corn respiration rates using pressure sensors

Proper grain management requires chronological and precise measurements of carbon dioxide evolved from grain respiration during the postharvest storage duration. The main goal of this research was to develop a new technique that evaluates temporal corn respiration rate using pressure sensors. The effects of corn storage temperature (23, 35, and 45 °C) and initial moisture content (12.9, 14.8, 17.0, 18.8, and 20.7% w.b) on the cumulative respiration were studied for duration of nine days. Additionally, the established technique was used to develop an empirical equation to predict the corn respiration rate as affected by storage temperature, moisture content, and storage duration. The pressure sensor method was found to be reliable in measuring corn respiration rate as affected by the tested parameters. The highest cumulative respiration of 2.625 g/kg was observed with the moisture content of 18.8% and the medium temperature level of 35 °C after nine days. Increasing and/or decreasing the moisture content level from 18.8% negatively affected the cumulative respiration. Respiration rates reached their maximum values of 0.199, 0.755, 0.987, and 1.147 g/kg.d under the medium temperature level of 35 °C and the moisture contents of 14.8% (5th day), 17.0% (5th day), 18.8% (3rd day), and 20.9% (2nd day), respectively. The logarithmic value of the corn cumulative respiration was positively correlated with the initial moisture content values, the storage temperature, and the storage duration with an adjusted coefficient of determination value of 0.80.

The impact of seaweed life phase and postharvest storage duration on the chemical and rheological properties of hybrid carrageenans isolated from Portuguese Mastocarpus stellatus

Abstract Variations in chemical and gelling characteristics of hybrid carrageenan extracted from Mastocarpus stellatus seaweeds are studied in order to explore potential links between the seaweeds life phase, the seaweeds postharvest storage duration and the phycocolloids properties. Chemical structures of phycocolloids were assessed by Fourier Transform Infrared spectroscopy (FTIR) and 1 H NMR spectroscopy. Rheological properties of hybrid carrageenans, such as intrinsic viscosity ([ η ]), gel elasticity ( G 0 ), gel setting temperature ( T g ) and gel melting temperature ( T m ), were measured with a stress rheometer. Seasonal variation in the degree of sulphates of native extracts and in their corresponding gelling properties is found. The minimum in gelling properties coincides with a minimum of fructified gametophytes in populations harvested during the cold season. Alkali treated extracts also show minimum gelling properties during the cold season but no correlation with variations in the chemical characteristics could be identified. The gel setting temperature is the only significant change in the properties of hybrid carrageenans extracted from dried seaweeds stored over 39 months in opaque and sealed plastic bags. These results point to non trivial relationships between the life stages of M. stellatus seaweeds, the chemical structure and gel properties of the alkali-extracted phycocolloids, and suggest a route towards the sustainable exploitation of the natural resource.

Postharvest shelf-life discrimination of nectarines produced under different irrigation strategies using NIR-spectroscopy

Quick assessment of storage time in fruits is important for both growers and consumers due to the fresh fruit market is becoming increasingly demanding with regard to product quality. This study sought to evaluate the ability of near-infrared reflectance spectroscopy (NIRS) to classify intact nectarines in post-harvest storage, as a function of pre-harvest irrigation strategies applied and post-harvest cold storage duration. A total of 220 nectarine fruits ( Prunus persica (L.) Batsch cv. ‘Sweet Lady’) were sampled after 7, 14, 21 and 28 days of refrigerated storage (0 °C, 95% RH) and at commercial harvest time. Two commercially-available spectrophotometers were evaluated for this purpose: a handheld MEMS spectrophotometer of 1600–2400 nm and a diode-array Vis/NIR spectrophotometer of 400–1700 nm. Models developed using partial least squares 2-discriminant analysis (PLS2-DA) correctly classified between 86 and 96% of samples by post-harvest storage time using the handheld instrument, and between 66 and 89% in the case of the diode-array spectrophotometer. Classification models based on pre-harvest irrigation treatment classified 57–84% of the samples correctly, due to the similarity in physical–chemical properties of fruits in both irrigation strategies. These results showed that NIRS could be used to monitor changes in nectarine quality parameters during pre- and post-harvest as an essential tool for decision-making both in-field and on-line.

Miniature handheld NIR sensor for the on-site non-destructive assessment of post-harvest quality and refrigerated storage behavior in plums

This study evaluated the feasibility of using a handheld micro-electro-mechanical system (MEMS) spectrometer working in the 1600–2400 nm range for the measurement of quality-related parameters (soluble solid content, firmness, variety and post-harvest storage duration under refrigeration) in intact plums. Spectroscopic measurements were also made for each fruit using a diode-array Vis–NIR spectrophotometer (400–1700 nm) for purposes of comparison. A total of 264 plums ( Prunus salicina L.) cv. ‘Black Diamond’, ‘Golden Globe’, ‘Golden Japan’, ‘Fortune’, ‘Friar’ and ‘Santa Rosa’, received and stored at 0 °C and 95% RH for 9 days, were used to build calibration models using different spectral signal pre-treatments and the modified partial least squares regression method. The two NIR instruments evaluated provided good precision, although the diode-array instrument yielded slightly greater precision for soluble solid content; statistic values were r 2 = 0.73 and the standard error of cross validation (SECV) = 1.11% for calibration, and r 2 = 0.68 and the standard error of prediction (SEP) = 1.22% for validation. Firmness measurements were less precise in both instruments, though again slightly better in the diode-array instrument: r 2 = 0.64 and SECV = 1.77 N for calibration; and r 2 = 0.61 and SEP = 2.30 N for validation, respectively. The performance of the two instruments for classifying plums by variety and by refrigerated post-harvest storage duration (0, 6 and 9 days) was evaluated using partial least square-discriminant analysis. A total of 96.5 % of samples were correctly assigned to their variety, while 94.5 % of plums were correctly assigned to their refrigerated storage day. In general, promising results were obtained with both instruments, with similar levels of accuracy for the measurements for soluble solid content, variety and refrigerated storage duration; the prediction model developed using the diode-array spectrophotometer provided better results for firmness.

Instantaneous quantitative and qualitative assessment of pear quality using near infrared spectroscopy

A comparative study was made of the performance of different spectrophotometers as part of a research into the potential of NIR reflectance spectroscopy as a non-destructive method for predicting soluble solid content, firmness and postharvest shelf-storage time in intact pears. Three commercially available spectrophotometers were used: a scanning monochromator (SM) of 400–2500 nm, a combination of diode array and scanning monochromator (DASM) of 350–2500 nm and a diode array (DA) of 900–1700 nm. A total of 332 pears ( Pyrus communis L.) cv. ‘Blanquilla’ and ‘Conference’ were used to develop calibration models in different spectral regions, using various spectral signal pretreatments. Models to predict soluble solid content yielded coefficients of determination ( r 2) ranging from 0.39 to 0.76, and a standard error of cross-validation (SECV) of between 0.59 and 1.49 °Brix, depending on the instrument used. Models for predicting firmness yielded r 2 values of between 0.45 and 0.79 and SECVs ranging from 5.33 to 7.36 N. Subsequently, the ability of these instruments to classify fruit as a function of postharvest shelf-storage time (0, 6 and 8 days) was tested using partial least squares discriminant analysis (PLS-DA), which yielded percentages of correctly classified samples (ratio of correctly classified samples to total samples) ranging from 81.1 to 94.4%, depending on the instrument used. The results obtained highlight the potential of these NIR instruments for assessing internal quality indices and predicting postharvest storage duration in pears, particularly when the instruments SM and DASM were used.

A rapid germination protocol for mile-a-minute weed, Polygonum perfoliatum L

A method for breaking dormancy and rapidly inducing germination of Polysonnnz perj%liarr elni:;d ,u,raficdltun, inunrlattun, culd.\re~ str3tific3lion CI'C), rvnrni-uct .trx~ficitiun (=23'C) and comhinniionf of lllccc treatm:nts After-ripened. sture.1 achenes that were scarified far 60 minutes in 93% sulfuric acid and inundated with deionized watdr germinated following three to four weeks of stratification at 4'C. A subsequent study showed that post-harvest storage duration (after-ripening) influenced the results of the germination protocol. Achenes germinated after one week of post-harvest storage at =23C, but a high germination percentage (85 + 4%) was not achieved until after five weeks of past-harvest storage. Achenes that were stratified in leachate water had lower germination percentages than achenes stratified in deionized water, but inhibition of germination was reduced over time. The results of these experiments suggest that P. pefoliot~mz achene dormancy is enforced by both coat-imposed and chemical-based mechanisms. Coat- imposed dormancy was overcome by scarifying achenes for 60 minutes in 93% sulfuric acid while chemical-based dormancy was overcome by storing freshly harvested achenes for at least one week at =23C and stratifying the seed in deionized water at 4°C tar four weeks.

Preserving Color in `Michigan Purple' Potatoes

The objective of this study was to evaluate preharvest fertilizer application and postharvest storage temperature and duration as they affect the intensity and stability of color in red and purple potato cultivars during storage. `Michigan Purple', `Dakota Rose', and `Chieftain' were stored at 4 °C and hue angle (h°) was measured weekly. The initial `Michigan Purple' h° of 1.1° changed to 23.2° after 18 weeks of storage (a shift in h° from 350° to 30° changes from purple to red) while the initial hue angle of 18.5° and 34.1° for red-skinned cultivars, `Dakota Rose' and `Chieftain', changed to 27.2° and 43.2°, respectively. Hence, the degree of color shift was greater in `Michigan Purple' although all the cultivars in this experiment underwent significant color change during storage. Hue angle of `Michigan Purple' tubers stored at 4°, 10°, and 20 °C for 8 weeks changed 19.4°, 12°, and 14.2° toward the redder h°, respectively. Thus, the color of `Michigan Purple' tubers changed the least at 10°C. Hue angle of `Michigan Purple' tubers fertilized with 180 lbs/acre slow-releasing nitrogen, 180 lbs/acre nitrogen, 270 lbs/acre nitrogen, and 2.5 lbs/acre poultry manure was measured after 5 weeks at 4 °C. Hue angles were 0.92°, 11.65°, 3.99°, and 1.34°, respectively. The hue of the first three treatments differed significantly from one another, but the hue of the potatoes treated with 180 lbs/acre slow-releasing nitrogen and 2.5 lbs/acre poultry manure did not differ. Preharvest factors like plant nutrition can influence tuber color in storage and `Michigan Purple' tuber color is particularly sensitive to storage temperature.