Calcium Pretreatments Research Articles

Effects of pre-storage calcium applications on physical and chemical attributes of potato

Pre-storage applications are of considerable importance in reducing chemical and physiological changes occurring in potato tubers during prolonged storage. The objective of this study is to determine the effect of increasing doses of pre-storage applied calcium on physical and chemical properties of potato tubers. The experiment was carried out in a completely randomized design with three replications at cold storage with +4 °C temperature and 85-90% moisture. The potato tubers were soaked in three calcium solutions (5%, 10% and 15%) for one hour, along with the control of pure water. The calcium pretreatments showed significant ameliorative effects on all physical and chemical attributes of four months stored potato tubers. With calcium application, sprouting tuber rate and shooting length decreased by 15% and 42% as compared to the control, respectively. The pre-storage applications of calcium significantly reduced the losses occurring in total phenolic content and antioxidant activity during storage. In conclusion, the present study suggested that pre-storage calcium applications could reduce storage losses occurring in potato tubers.

Salicylic acid and calcium pretreatments alleviate the toxic effect of salinity in the Oueslati olive variety

Abstract Pretreatment in arboriculture is a new physiological approach allowing the improvement of plant tolerance to salt stress. This research aims to screen various pretreatments of salicylic acid (SA) and/or calcium chloride (CaCl2) to mitigate the effect of salinity on ‘Oueslati’ olive plants (Olea europeae L.) on physiological attributes under 200 mmol L−1 of NaCl application. One - year- old plants were transplanted to sand culture in a greenhouse, and were pretreated with two levels of foliar application of SA (0.5 and 1 mmol L−1) and by adding CaCl2 (10 and 20 mmol L−1) to the culture solution twice a week for 45 days. At the end of the pretreatment, the plants were subjected to 200 mmol L−1 NaCl exposure for 75 days. The result showed that shoots and roots growth were decreased significantly due to salinity, sodium (Na+) ions increased and K+/Na+ ratio decreased in leaves. Rate of assimilation (A), transpiration (E) and stomatal conductance (gs) decreased in leaves. Salinity caused significant increase in both malondialdehyde (MDA) and H2O2 concentration, a decrease in total polyphenol and flavonoid levels and an increase in scavenging activity (IC50) (21%). Moreover, salinity caused a decrease in xylem and an increase in phloem thickness in leaves. However, pretreatments could partly improve the adverse effects of salinity on the most studied parameters. SA (1 mmol L−1) is able to restrict Na+ ions transport from the roots to the leaves limiting its toxicity in the sensitive organs. SA (1 mmol L−1) and CaCl2 (10 mmol L−1) pretreatment alleviate the effects of salinity on dry weight of shoots and roots as well as, photosynthetic activity in pretreated plants. Moreover, at the same pretreatment, results showed a decrease of the Na+ translocation to the leaves. Furthermore, it has been shown that pretreatment of ‘Oueslati’ olive plants enhance the non-enzymatic antioxidant activity (total polyphenol and flavonoid content).These results suggest that pretreatments may be useful methods to increase salt tolerance in olive, for use in arid and semi-arid environments.

The effect of calcium chloride and calcium lactate pretreatment concentration on peach cell integrity after high‐pressure processing

SummaryThe objective of this study was to determine the effect of calcium chloride and calcium lactate pretreatments at different concentrations (1, 1.5 and 2% w/v) on enzymatic browning of clingstone and freestone peaches following high‐pressure processing (HPP) at 200 MPa for 10 min. Proton nuclear magnetic resonance (1H‐NMR) relaxometry indicated that following calcium pretreatment and HPP, both peach types had lower percentages of water in the vacuole compartment and a simultaneous increase in the percentage of water in the cytoplasm compartment. Calcium pretreatment of freestone peaches did not affect the development of browning, regardless of the form of calcium or the concentration, whereas calcium lactate pretreatment undesirably enhanced clingstone peach discoloration. Calcium pretreatments have the potential to reduce the loss of cell integrity that results from HPP; however, in this study, the effect was not sufficient to inhibit the interaction between the polyphenol oxidase enzyme that catalyses browning and its substrates.

Effect of pretreatments on carrot texture after thermal and pressure-assisted thermal processing

The effect of various physical and chemical pretreatments such as pressure (100–400MPa), temperature (50–70°C), calcium chloride (0.5–1.5% w/v), and their combinations on carrot texture was studied after pressure-assisted thermal processing (PATP) and thermal processing. Untreated PATP and thermally processed samples without any pretreatment served as controls. Individual pretreatments were effective to a limited extent in improving the product quality. Pressure (200MPa), heat (60°C) and calcium chloride (1.0%) pretreatments increased product hardness by 1.2, 2.0 and 2.4 times after PATP and 2.7, 3.6 and 2.4 times, respectively, after thermal processing. Combined pretreatments increased the hardness of the samples by 9.16 times (from 14.08 to 129.07N) and 13.22 times (from 4.36 to 57.63N), respectively, in comparison to untreated PATP or thermally processed samples. The calcium content of the samples was found to have a positive influence in preserving hardness. The microstructure analysis of PATP carrots indicated that the combined high pressure, heat, and calcium pretreatments better preserved cell structure. This combined pretreatment process could serve as an effective tool in preserving the quality of PATP as well as thermally processed carrot.

Ultrastructural and Changes in Pectin Composition of Sweet Cherry from the Application of Prefreezing Treatments

Thermal and calcium pretreatments applied to preserve the sweet cherry texture by the freezing/thawing process produced biochemical changes in the pectic substances and ultrastructural alterations to the cells and tissues, which were visible under scanning electron microscopy. Partial dehydration of the epidermic tissue caused by calcium (100 mM CaCl2) and thermal (50 °C/10 min) pretreatment attenuated the surface damage produced by freezing. However, pretreatment at 70 °C/2 min caused partial destruction of the epidermic tissue and plasmolysis of the parenchymatic cells. After freezing, the cell walls in the parenchymatic tissue of the fruits pretreated with 100 mM CaCl2 exhibited swelling as a result of gelling of the cell-wall pectic material. Thermal pretreatments increased the ethylenediaminetetraacetic acid (EDTA)-soluble pectin fraction and reduced the degree of pectin esterification. Thermal treatments at 70 °C, without immersion in calcium, reduced the water- and pectinase-soluble pectin fractions, whereas immersion in calcium prevented depolymerization of these fractions. Immersion in 100 mM CaCl2 increased the water-soluble pectin fraction.

Comparison of drying kinetics and texture effects of two calcium pretreatments before microwave‐assisted dehydration of apple and potato

SummaryThe effects on drying rate and texture of treating two plant tissues with calcium, before drying in air with microwave assistance, were studied in this work. The two tissues, potato and apple cubes, which have different structures and composition, were pretreated by immersion in CaCl2 solutions at 20 or at 70 °C before microwave‐assisted air dehydration at 50, 60 and 70 °C. The pretreatments with calcium influenced the strength of the plant tissue cell wall, producing products of varying hardness after rehydration. The effect of the two calcium pretreatments was quite different for apples and potatoes. For apples, calcium pretreatment at 20 °C increased the hardness of rehydrated apples compared with untreated apples, but calcium pretreatment at 70 °C had no effect on texture. For potatoes, both calcium pretreatments at 20 and at 70 °C significantly increased the hardness of rehydrated potatoes. The water diffusivity during drying varied mainly because of the type of plant tissue, with secondary effects caused by the drying temperature and the type of calcium pretreatment.

395 Storage Disorders of Araza Fruit (Eugenia stipitata Mc. Vaugh) Related to Postharvest Treatments

Araza (Eugenia stipitata Mc Vaugh) is a plant from the Myrtaceae family originated from Amazonia. The postharvest behavior of its promissory fruit has been sparingly studied. Weight loss, softening, decay, and chilling injury (skin scald) at temperatures below 10-12 °C limits its shelf-life to less than 10 days. The application of calcium pretreatments slightly improved flesh firmness after 7 days at 20 °C and resulted in skin injury, particularly at concentrations higher than 4% (w/v). A warming treatment of 6, 12 or 18 h at 20 °C was applied to fruit after 6 d storage at 10 °C. Treated fruit had less scald, suppressed decay, and ripened normally after a total of 2 weeks of storage and a shelf life of 3 days.

Effect of Calcium Pretreatments on the Texture of Frozen Cherries. Role of Pectinesterase in the Changes in the Pectic Materials

This work has been financed by the Comision Interministerial de Ciencia y Tecnologia (C.I.C.y.T., Projects ALI9110728 and ALI941943)