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Global market demand for minimally processed (fresh cut) table grapes is increasing due to the premium product quality and easiness in consumption as they are ready-to-eat. However, fresh table grapes necessarily deteriorate after harvest due to their delicate tissue and preparation operations. Therefore, innovative technologies for the postharvest quality maintenance of minimally processed fresh grapes are required. In this study, berry quality, biochemical features and bioactive compounds of minimally processed (berry pedicel detached) grapes (Vitis viniferacv. ‘Crimson Seedless’) as affected by postharvest immersing the berries in melatonin at different concentrations (0, 0.1, 1 and 10 mmol L−1) were investigated with a 7-day interval during storage at 1.0 ± 0.5 °C for 35 days. Melatonin dips at all doses significantly extended the physical and biochemical quality of minimally processed (stem excised) grapes by restricting polygalacturonase activity and retarding the losses in berry weight, skin rupture force and visual quality. Melatonin treatments also effectively delayed the changes in berry skin color, phenol content, antioxidant activity and many other biochemical components in berry must. For a sustainable storage of the minimally processed table grapes, a 1-mmol L−1melatonin concentration can be recommended due to its relatively higher effectiveness over other doses as well as cost-effectiveness of the lower doses.

This study aimed to reveal the effects of different concentrations (0, 5, 10, and 20%) of Aloe veragel (AV) coating on the quality-related characteristics of table grapes (‘Alphonse Lavallée’ and ‘Red Globe’) during cold storage at 1.0 ± 0.5 °C with 90 ± 5.0% relative humidity for 75 days. Sulphur dioxide (SO2) was also used as a common chemical-based postharvest application to compare the effectiveness of the treatments. During the cold storage, AV treatments were remarkably effective in delaying the loss in fresh weight of grapes with greater effects than both the control and SO2. Postharvest changes in biochemical features such as the soluble solid contents (SSC), titratable acidity (TA), and maturity index (MI) of both grape cultivars were significantly delayed by AV concentrations. Higher concentrations of AV displayed better protection in the physical, biochemical, and visual quality-related properties of the grape cultivars. Considering the general findings, the use of 10% AV treatment could be recommended as a natural, safe, and healthy alternative strategy to chemicals as it provided better conservation of the fresh grapes in long-term cold storage.

Edible coating is an environmentally friendly, safe, and effective practice to extend the physical and biochemical qualities of fresh commodities. The present study evaluated the effects of preharvest Aloe vera(AV) spraying 1 week before harvest (25%), postharvest AV coating (25%), and their combined use on the quality of table grape (‘Sultani Cekirdeksiz’ syn.‘Thompson Seedless’) during cold storage at 1.0 ± 0.5 °C and 90 ± 5.0% relative humidity for 120 d. Berry adherence was significantly improved by preharvest AV pulverization by increasing the berry detachment force, a prime feature determining the storage and marketing lifetime of table grapes. Both preharvest and postharvest AV treatments remarkably delayed the loss in weight and maintained the rachis chlorophyll content and antioxidant capacity during the storage. Visual quality was obviously higher in grapes subjected to both treatments. Overall investigations showed that both treatments significantly maintained the storage lifetime of the grapes. Based on the findings, AV treatment as a natural and healthy compound could be used as a suitable alternative to extend the marketable period of table grapes and minimize postharvest losses.

A brief investigation of the effects of oxidation on the calorific values of three Turkish lignite samples has been made. The lignite samples have been vacuum dried and oxidized in pure oxygen at 35, 45, and 55 C at 100 kPa for 10 days. The calorific values of the oxidized and unoxidized samples have been measured. A relation has been observed between the extent of oxidation and decrease in calorific value. Various possibilities of modelling the relation have been explored.

A DTA study has been made to investigate the thermal reactivities of five Turkish lignites (Elbistan, Ilgin, Karliova, Xangal, Yatagan) in an air atmosphere. The coal samples exhibited thermal reactivity at temperatures starting from 20 °C and continuing up to 671 °C. Endothermic peaks were observed at the lower end of the temperature range, the highest endothermic peak temperature being 146°C for Elbistan lignite. Exothermic peaks appeared at around 260, 360 and 600 °C. These temperatures are considered to signify the release and combustion of single benzene ring structures and combustion of condensed aromatic rings respectively. Corresponding stages are observed in the TGA traces. After correcting for differences in methodology, the overall heat effects measured by DTA are within greater than 90% of the calorific values of the coal samples determined by bomb calorimetry.