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This paper presents the results of the comparison of different analytical techniques (Differential Scanning Calorimetry - DSC, Low Field Nuclear Magnetic Resonance - LF-NMR, Light Microscopy - LM and Transmission Electron Microscopy – TEM) in order to evaluate the mass transfer, water status and cellular compartment modifications of the kiwifruit outer pericarp tissue during osmotic dehydration treatment (OD). Two kiwifruit species, A. deliciosa and A. chinensis were submitted to OD. OD was performed in a 61.5 % w/v sucrose solution at three different temperatures (25, 35 and 45 °C), with treatment time from 0 to 300 min. Peleg’s model highlighted that the main response differences between the two kiwifruit species occurred during the initial phase of the osmotic treatment. DSC parameters appeared to be sensitive to water and solid exchange between fruits and osmotic solution. LF-NMR proton T2 revealed the consequences of the water-solid exchange on the cell compartments, namely vacuole, cytoplasm plus extracellular space and cell wall. During OD, the reduction of the vacuole proton pool, detected by LF-NMR, suggested a shrinkage of such compartment, confirmed by LM. Cell walls of outer pericarp showed considerable changes in size, structure and stain uptake during OD observed at TEM. The proposed multianalytical approaches should enable better design of combined processing technologies permitting the evaluation of their effects on tissue response. U ovom radu su prikazani rezultati poređenja različitih analitičkih tehnika (Diferencijalna skeniranja Kalorimetrija – DSC, Niska Polje nuklearna magnetna rezonanca - LF-NMR, svetlost mikroskopije - LM i Prenos elektronsku mikroskopiju - TEM), u cilju određivanja prenosa mase, statusa vode i modifikacije ćelija tkiva perikarpa kivija tokom osmotske dehidratacije tretmana (OD). Dve sorte kivija su bile izložene osmotskom tretmanu, A. deliciosa i A. chinensis. Osmotsko sušenje obavljeno je u 61,5% rastvoru saharoze na tri različite temperature (25, 35 i 45°C), sa vremenom trajanja sušenja od 0 do 300 minuta. Pelegovim modelom naglašene su glavne razlike između dve sorte kivija koje se događaju tokom početne faze osmotskog tretmana. DSC parametri osetljivi su na izmenu vode i čvrste materije između voća i osmotskog rastvora. LF-NMR-om otkrivene su posledice razmene vode i čvrste materije na ćeliju, odnosno vakuole, citoplazmu sa vanćelijskim prostorom i ćelijski zid. Tokom OD, smanjenje vakuole protona bazena, otkrivena je LF-NMR, predložio skupljanja takvog odeljka, potvrđeno LM. Ćelijske zidove spoljne perikarpa su pokazali značajne promene u veličini, strukturi i mrlja uzimanja u toku OD posmatrano na sistem. Predloženi multianalitical pristupi treba da omogući bolji dizajn u kombinaciji obrade tehnologija dozvoljava procenu njihovog uticaja na tkivo odgovor. Fil: Dalla Rosa, Marco. Università di Bologna; Italia Fil: Tylewicz, Urszula. Università di Bologna; Italia Fil: Panarese, Valentina. Università di Bologna; Italia Fil: Laghi, Luca. Università di Bologna; Italia Fil: Pisi, Annamaria. Università di Bologna; Italia Fil: Santagapita, Patricio Roman. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Rocculi, Pietro. Università di Bologna; Italia

In this research, recent results of isothermal calorimetry studies focused on differently processed and stored fresh-cut fruit are presented. Particularly the calorimetric approach has been applied in order to better understand the physiological response of fresh-cut kiwifruit, apple and cantaloupe tissues as a consequence of: - osmo-dehyration in sucrose solution for different treatment times, on the metabolic heat production of fresh-cut kiwifruit; - modified atmosphere exposure, on the metabolic heat production of fresh-cut apples, with an innovative instrument set-up; - storage in different syrup formulations, on the microbial growth heat production on fresh-cut cantaloupe. Obtained results are very promising, evidencing important aspects such as: - a progressive metabolic heat reduction of kiwifruit tissue with the proceeding of the osmotic treatment; - the inhibitory effect of specific gas mixtures with traditional and/or innovative packaging gases in terms of metabolic heat production of apple tissue; - the potentiality of this technique for the optimization of syrup formulation, in order to increase the microbiological stability of fresh-cut cantaloupe.

Osmotic dehydration is a partial dewatering process by immersion of cellular tissue in a hypertonic solution, which is accompanied by solutes counter-diffusion into the tissue. Low field-nuclear magnetic resonance (LF-NMR) seems to be a promising technique to follow the distribution of water/solutes through the cellular tissue during treatment. The objective of the present study was to evaluate the cellular compartment modifications of kiwifruit (Actinidia deliciosa) outer pericarp tissue caused by osmotic treatment in a 61.5% sucrose solution through the quantification of transversal relaxation time (T2) and water self diffusion coefficient (Dw) obtained by LF-NMR means. Proton T2 of the samples was measured using CPMG sequence. Three T2 were obtained of around 30, 200 and 1000 ms, which could be ascribed to the protons located in the cell walls, in the cytoplasm/ extracellular space, and in vacuoles, respectively and could be directly compared to those described in the literature for several fruits and vegetables. Vacuoles T2 represented around 66% of total kiwifruit protons. The leakage of water leading to vacuoles shrinkage seemed to cause a concentration of solutes, retained by the tonoplast, making the vacuoles T2 decrease at each treatment time. Dw were measured by means of the pulsed field spin-echo (PFSE) sequence. As expected, the kiwifruit Dw values measured in the raw kiwifruit were lower than free water one, as the structures and solutes of raw kiwifruit reduce water mobility, and decrease even more during osmotic treatment, due to the water loss and sugar gain. The coefficient measured by means of PFSE represented an average value of the whole kiwifruit tissue protons. In order to obtain Dw values specific for each cellular compartment, a two compartment fitting was also used. The Dw correspondent to vacuoles was much higher than the average one Dw.

[Excerpt] Introduction: There is only little information available in the literature about the effect of reversible electropermeabilization on plant cells and tissues. We here present a first exploration of the effect of pulsed electric fields (PEF) on barley seed germination. PEF is used as a physical means of stressing the seeds and affect their metabolism. [...], info:eu-repo/semantics/publishedVersion

In this study calorimetric measurements provided evidence of a drastic increase of spinach leaf gross metabolism as a consequence of vacuum impregnation (VI) at a minimum pressure of 150 mbar with trehalose and sucrose isotonic solutions. When applying VI extracellular air is replaced by the impregnation solution, potentially limiting tissue respiration to any remaining air volume in the tissue. However the observation that impregnated leaves showed photosynthetic activity suggests that not all air was exhausted during VI. Hence impregnation appears to reach a maximum with remaining gas filled compartments. Metabolic inhibitors impregnated together with sugars showed that the short-term metabolic response, causing the drastic increase of gross metabolism upon VI, depends on mitochondrial oxygen consuming pathways. The metabolic effect following mannitol impregnation was comparable with water impregnation, suggesting that the strong metabolic effect reported here is only seen for molecules that can be metabolized and provide energy to the cells. Industrial relevance: Vacuum impregnation is used to incorporate additives in fruit and vegetable tissues, such as anti-browning agents, microbial preservatives or cryoprotectants. As a promising technology in the food industry, deeper insights on the metabolic consequences of vacuum impregnation are required to define and control the shelf-life of the processed fruits and vegetables. (C) 2014 Elsevier Ltd. All rights reserved. (Less)