Search

IntroductionWhile grapes are considered as non-climacteric fruits, during the post-harvest stages, due to the softening of the tissue, it is very prone to decay, which shortens its post-harvest life. Today, due to the desire of consumers to use high quality food, the use of biodegradable films and coatings with antimicrobial properties, is a suitable alternative to synthetic preservatives, in order to maintain food security and prevent wastage of significant capital. Edible coatings are edible thin layers that are used to increase the shelf life and quality of fruits. This material increases the quality and health of the product by creating a semi-permeable barrier to water vapor and oxygen and carbon dioxide gases between the product and the environment, and to prevent anaerobic respiration, it absorbs a certain amount of gases and to this Sequence increases product shelf life. One of the most important ways to increase the shelf life and maintain the quality of agricultural products, especially fruits, is the use of edible coatings on the crop surface. Chitosan is one of the most important natural derivatives of chitin, of which about 50% of its acetyl’s groups have been removed. Due to the fact that Aloe vera gel has no taste and odor, can be considered a good option as a cover for fruits after harvest and due to its elasticity and strength solution in water, as a suitable layer on the product. Located and protects the fruit from mechanical damage and moisture loss. Material and Methods In this study, 12-year-old mature grape trees of ‘Asgari’ cultivar in the scaffolding garden of Abestan region of Khorramabad city in 1398 were studied. In the pre-harvest stage, chitosan was sprayed on the tree and in the post-harvest stage, Aloe vera gel was applied by dipping the fruit in Aloe vera gel in the laboratory. After treatment, the fruits were stored in the refrigerator at a temperature of 4 ± 0.5 ° C and were examined at different time stages for quantitative and qualitative characteristics of the fruit. 20 identical grape trees (in terms of fruit size and load, with 50 to 70 annual branches in 8-14 buds) selected and grape clusters with different concentrations of chitosan (control (distilled water), 2 and 3 Percentage of chitosan) at different stages of growth (fruit set), 35 and 50 days later) were sprayed directly with 4 liters per vine, by hand sprayer (2 ml Tween 80% was added as the active surfactant). For this stage, immediately after harvesting the grapes, take them to the laboratory and immerse them in concentrations (zero, 25 and 33%) of Aloe vera gel for 10 to 20 seconds and then in the air. They dried. Then, grape fruits weighing about 360-300 g in each experimental unit were stored for 28 days at 4 ° C and examined. This study was performed as a factorial experiment (2 factors) in a completely randomized design with three replications. The first factor is the effect of the treatments studied in seven levels including: control, 2% chitosan (CTS 2%), 3% chitosan (CTS 3%), chitosan 2% + Aloe vera gel 25% (AVG 25% + CTS 2%), chitosan 3% + Aloe vera gel 25% (AVG 25% + CTS 3%), 2% chitosan + 33% Aloe vera gel (AVG 33% + CTS 2%), chitosan 3% + Aloe vera gel 33% (AVG 33% + CTS 3%) and the second factor was storage time at five levels (zero, 7, 14, 21 and 28 days after harvest). Data analysis was performed using SAS software and a significant difference between treatments for each trait with a minimum significant difference at the probability level = 0.05 α was determined. Results and Discussion The results of analysis of variance showed that the effect of treatment and storage time on the desired traits was significant at the level of one percent. Fruits treated with chitosan and Aloe vera gel had higher texture firmness, taste index, phenolic content, antioxidant activity and titratable acids and caries index and pH were lower than the control. The highest content of phenol, antioxidant, flavor index and titratable acidity in all five measurement times belonged to 2% chitosan treatments with both concentrations of Aloe vera gel (25 and 33%) and the lowest amount belonged to the control treatment. In control treatment, the percentage of caries index increased during storage and in grapes treated with chitosan and Aloe vera gel, the caries process was slower and the lowest rate of caries was observed in 2% chitosan treatment with aloe vera gel on the 14th day. In general, it was observed that pre-harvest application of chitosan and post-harvest Aloe vera gel increase the post-harvest life of ‘Asgari’ grapes and improve its quality traits. Chitosan creates a barrier with selective permeability to oxygen and carbon dioxide gases, and by placing carbon dioxide at a higher level and reducing oxygen, it creates a modified atmosphere around the fruit, which reduces respiration and ethylene production. As a result, it reduces the aging process and reduces the consumption of organic acids and sugars and prevents the increase of pH. Low pH prevents browning of the fruit due to the activity of catechins and chlorogenic acid enzymes. Aloe vera gel coating maintains and increases the antioxidant capacity of the whole fruit by reducing fruit juice loss, reducing respiration, reducing ethylene production and delaying aging. Conclusion The combined treatment of chitosan 2% and Aloe vera gel (25 and 33%) increased fruit firmness, titratable acidity, taste index, total phenol content and antioxidant activity of grapes and reduced pH and caries index. Application of these treatments increased the post-harvest life of ‘Asgari’ grapes by 14 days, so it can be stated that the use of chitosan in the pre-harvest stage and the use of Aloe vera gel in the post-harvest stage as biodegradable and natural compounds to increase Shelf life of ‘Asgari’ grape fruit is recommended.

Non-degradable coatings made of petroleum-based plastics hinder the degradation performance of products. This highlights the urgent need to develop biodegradable, bio-based coatings derived from renewable resources to create a more sustainable and greener world with a smaller environmental footprint. This study endeavours to examine the effects of beeswax and coconut oil additions on the morphological, degradation, and water-barrier properties of mycelium-based composite (MBC). Coconut oil is supplemented with varying amounts of beeswax, comprising 0, 20, 40, 60, 80, and 100 wt%. Dip coating is applied to prepare coated-MBC at 65 °C for 2 min. The coated-MBC is characterized by water absorption test, water loss measurement, density measurement, yeast and mould test, shrinkage measurement, weight loss measu rement, soil burial test, Scanning Electron Microscopy (SEM) and macroscopic appearance. Findings revealed that a higher composition of beeswax (80 BW) leads to lower water absorption ability (26.25 %) and no fungal growth for 36 days, in contrast to uncoated-MBC (0 BW), which are used as a reference sample. • Various compositions of beeswax are incorporated into coconut oil at 0, 20, 40, 60, 80 and 100 wt.%. • Uncoated mycelium-based composite serves as the reference. • As the proportion of beeswax in the coating increases, the water-repellent ability of the mycelium-based composite improves due to the hydrophobicity nature of beeswax. • In addition, mycelium-based composites coated with higher proportions of beeswax exhibit a lower density, higher surface roughness, slower degradation rates and reduced weight loss. [ABSTRACT FROM AUTHOR]

Manna is the sap extracted in summer from the phloem of the stem and the old branches of Fraxinus sp. trees. Its composition is characterized by a high content of D-mannitol, gallic acid, tyrosol and a great antioxidant activity. The aim of the present work was to compare the effect of a solution enriched with manna or calcium ascorbate, the latter widely used by researchers as an antioxidant agent on the control of browning of apple slices. After harvest, apple fruit were cut, treated with manna (MN), calcium ascorbate (CA) or with distilled water as a control (CTR), and packed in polylactic acid (PLA) packaging. Physical, chemical and sensory analyses were performed after 3, 5, 7 and 10 days of storage at 5±0.5 °C. After one week of storage, manna and calcium ascorbate-based treatment significantly inhibited apple fruit slices browning of cut surface, to the same extent, while no significant differences occurred in terms of weight loss, DPPH, total carotenoids and flavor score. On the whole, manna may inhibit apple slices water loss without affecting fruit flavour and providing the maintenance of their shelf-life. It seems that manna and calcium ascorbate mechanism and effect on browning inhibition are very similar and account for maintaining stored apple slices shelf-life up to 7 days. Therefore, our work lays the foundations for the use of manna as a natural antioxidant compound capable of reducing fresh-cut enzymatic browning • Manna composition is characterized by gallic acid, tyrosol and antioxidant activity. • Manna treatment reduced softening and weight loss. • Manna and calcium ascorbate effect on browning inhibition are very similar. • Manna treatment application didn't affect apple slices flavor. • The increases of phenols can promote browning on the cut surface of apple. [ABSTRACT FROM AUTHOR]

Ahuyama (Cucurbita moschata) is recognized by its nutritional value, as it is composed of vitamin A, carbohydrates, phosphorus and minerals. Also, for its content of 45 % of total carotenoids; 66 % of β-carotene; 33 % of α-carotene, and 44 % of lutein. However, its high amount of water, about 90%, is conducive to bacterial and/or fungal growth reducing its useful life. Present study evaluated every three days, over a total of 12, three repetitions and three replications of freshly cut green bolus squash variety. Physicochemical attributes like weight, color, firmness, and respiration rate were observed, as well as those microscopic (MOAR and MET); bromatological, and microbiological characteristics to 4 different treatments as follow: SN (control sample); CV (Vinyl wrap); CR (coated with cassava starch and 1 % thyme essential oil); and CB: (binary system with natural source coating and Vinyl wrap) under environmental conditions of 19 °C temperature and 77,75 % average humidity. Vinyl wrap treatment exhibited lower weight, firmness loss, fewer respiration rate loss, and had better color stability. Control and coated samples showed higher sugar and moisture content but lower ash and protein. Additionally, samples with coated and uncoated stretch film registered minor fungal growth. Fresh cut squash could be properly preserved through the use of low-density polyethylene films (vinyl wrap), allowing to effectively delay the course of quality loss because of handling operations. [ABSTRACT FROM AUTHOR]

The effect of Tragacanth gum (T) coating containing (100, 500, and 1,000 mg/L) Satureja khuzistanica essential oil (S), Zataria multiflora Boiss. essential oil (Z), and (1,000 mg/L) sodium metabisulfite (M) on mushroom (Agaricus bisporus) enzymatic browning and postharvest quality was examined throughout 16 days of cold storage. Mushroom respiration rate, soluble solids content (SSC), percentage of open caps, and sensory quality as well as factors related to browning such polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL), and peroxidase (POD) activities were figured out. The significant decrease in respiration rate, cap opening delay, and SSC enhancement was observed after treating mushrooms with TZ and TS. Moreover, TZ‐ and TS‐treated mushrooms prevented enzymatic browning through inhibiting PPO and POD activities and increasing activity of PAL over the storing term. Additionally, the influence of TZ5 and TS5 (containing 500 mg/L essential oil) coatings was validated by sensory evaluation through protecting the overall quality of button mushrooms over the storage. Thus, Tragacanth coating enriched with essential oils might be an encouraging nomination for improving the modality of button mushroom and expanding its shelf life. [ABSTRACT FROM AUTHOR]

Mango is the "king of tropical fruits" because of its attractive appearance, delicious taste, rich aroma, and high nutritional value. However, mango keeps fast metabolizing after harvest, leading to water loss, starch conversion into sugar, texture softening, and decay. Here, a gas barrier coating based on cellulose nanocrystals (CNCs) is proposed to control the post-harvest metabolism of mango. The results of gas barrier permeability show that CNCs enhance the barrier ability of the chitosan (CS) membrane on mango by 202 % and 63 % for oxygen and water vapor, respectively. The gas-barrier coating reduces the climb in pH and the decrease in firmness by 84.9 % and 45.8 %, respectively, decelerating the conversion process from starch to sugar. Besides, introducing clove essential oil (CEO), the CEO mainly adsorbs and crystalizes on the hydrophobic facets of CNCs, presenting high compatibility, increases the antibacterial rate to nearly 100 %. As a consequence, the preservation period of the mango coated by the CNC-based membrane is at least 7-day longer than the control group. Such a gas-barrier coating based on eco-friendly composites must have excellent potential in the preservation of mango, and even for other tropical fruits. [Display omitted] [ABSTRACT FROM AUTHOR]

The hygroscopicity of a wooden material or the ability to absorb, store and release moisture helps to naturally regulate the indoor climate by dampening humidity variations and avoiding extremes. This phenomenon, known as moisture buffering, is an energy-efficient way of moderating moisture levels in a living space, improving air quality, and influencing the health and comfort of the occupants. This work focused on developing a surface treatment that preserves the natural ability of timber to buffer moisture vapor while increasing the resistance to liquid water. For this purpose we suggest a method based on a natural non-continuous coating of hydrophobic Carnauba wax particles. The coating was compared, in terms of water repellency and moisture buffering efficiency, to a continuous wax film and conventional coating methods like lacquer and linseed oil. The resistance of the surfaces to liquid water was studied by contact angle measurement. Moisture buffering experiments were conducted by exposing the surfaces to cyclic changes in relative humidity. It was found that coating with wax particles resulted in more hydrophobic surfaces with enhanced moisture buffering ability, while the rest of the coatings examined either reduced moisture buffering drastically (wax film, lacquer) or were not sufficiently hydrophobic (linseed oil). [ABSTRACT FROM AUTHOR]

Weathering is a geological/geo-environmental process that degrades and transforms rocks, contributing to landslides and instability of geo-systems and infrastructures. The effects of weathering on rock characteristics at the grain scale is crucial for understanding the impact of geological environment-processes on the physical and mechanical behavior of rocks, as well as how these processes are linked to the large-scale behavior of geological systems. In the present study, an investigation on the tribological behavior of highly and completely decomposed granitic rock (termed HDG and CDG, respectively) is presented using micromechanical-based experimental and analytical methods on miniature specimens. Emphasis is placed on examining the influence of the weathering degree and by taking into account analog ground-environment interaction effects on the constitutive (contact) behavior and interface friction of the weathered rocks. The high roughness and coating exposed on the surfaces of the tested samples because of the decomposition of feldspars and micas had important influences on the tribological behavior of the rock. Significant differences were also observed based on the state of the specimens, i.e., nominally dry, immersed in water, or by removing the surface coating from a washing process. An attempt was made to understand the differences between variously weathered materials and provide some basic modeling that can be useful in discrete-based analyses of geomechanics and engineering geology problems. Comparing a broad range of geological materials, including granite of grade I-II revealed that the transportation-sedimentation process and in-situ chemical weathering or rock crushing resulted in significant variabilities in the surface morphological characteristics of the grains. In some aspects of their tribological behavior, HDG grains (grade IV) were rather similar to grade I-II compared with the observed response of grade V. Analog wetting-drying cycles, simulated based on cyclic normal contact tests revealed significant accumulation of plastic displacements for the weathered rocks compared with sedimentary type materials, which implies higher sensitivity of weathered rocks to stress state changes caused by various geo-environmental influences. This is crucial to be considered in the constitutive modeling of ground-environment interaction. • The influence of weathering degree was examined testing granitic rock samples. • Grades IV and V were compared with data on grade I-II of granite and also other rocks/soils. • Analogue ground-environment interaction and wetting-drying cycles were simulated. • The data showed important differences between various rock/soil types in terms of friction. • Ground-environment influences affected the relative role of weathering degree. [ABSTRACT FROM AUTHOR]

The study of the collision behavior of solid objects has received a significant amount of research in various fields such as industrial applications of powders and grains, impacts of proppants and between proppant and rocks during hydraulic fracturing, and the study of debris flows and avalanches and the interactions of landslide materials with protective barriers. This problem has predominantly been studied through the coefficient of restitution (COR), which is computed from the dropping and rebound paths of particles; its value corresponds to 1 for perfectly elastic impacts and 0 for perfectly plastic impacts (i.e., at the collision there is no rebound of the particle). Often, the colliding particles (or particle–block systems) are not perfectly clean, and there is debris (or dust) on their surfaces, forming a coating, which is a highly possible scenario in the debris flows of natural particles and fragments; however, the topic of the influence of natural coatings on the surfaces of particles on the collision behavior of particle–block systems has been largely overlooked. Thus, the present study attempts to provide preliminary results with respect to the influence of natural coating on the surfaces of sand grains in the COR values of grain–block systems using a stiff granitic block as an analogue wall. Montmorillonite powder, which belongs to the smectite clay group, was used and a sample preparation method was standardized to provide a specific amount of clay coating on the surfaces of the sand grains. The results from the study showed a significant influence of the smectite coating in the COR values of the grain–block systems, which was predominantly attributed to the dissipation of energy at the collision moment because of the compression of the soft coating of microparticles. Additionally, the method of analysis for calculating the COR values based on one and two high-speed cameras was explored, as the impacts of natural grains involve deviations from the vertical, which influences the rebound paths. Thus, a sensitivity analysis was performed investigating the differences in the COR values in two-dimensional and three-dimensional analysis of the impact tests. [ABSTRACT FROM AUTHOR]

Pine pitch canker (PPC) is a major threat to pine forests worldwide because of the extensive tree deaths, reduced growth, and degradation of timber quality caused by it. Furthermore, the aggressive fungus responsible for this disease (Fusarium circinatum) can also infect pine seeds, causing damping-off in young seedlings. This study proposes an approach based on coating treatments consisting of natural products to ensure seed protection. Seeds from two pine species (the most sensitive to this disease, Pinus radiata D. Don, and a more resistant one, Pinus sylvestris L.) were coated with single and binary mixtures of low and medium molecular weight chitosan and/or ethanolic-propolis extract. The germination rate, pre- and post-emergence mortality, total phenolic content, and radical scavenging activity were assessed. All treatments, and especially the one based on chitosan oligomers, had a beneficial impact on P. sylvestris seedlings, significantly enhancing survival rates and displaying a positive influence on the total phenolic content and on the seedlings' radical scavenging activity. Conversely, non-significant negative effects on germination percentages were observed in the case of P. radiata seeds. The proposed treatments show promise for the protection of P. sylvestris seedlings against PPC. [ABSTRACT FROM AUTHOR]