Gums induced microstructure stability in Ca(II)-alginate beads containing lactase analyzed by SAXS

[EN] Previous works show that the addition of trehalose and gums in ß-galactosidase (lactase) Ca(II)-alginate encapsulation systems improved its intrinsic stability against freezing and dehydration processes in the pristine state. However, there is no available information on the evolution in microstructure due to the constraints imposed by the operational conditions. The aim of this research is to study the time course of microstructural changes of Ca(II)-alginate matrices driven by the presence of trehalose, arabic and guar gums as excipients and to discuss how these changes in¿uence the di¿usional transport (assessed by LF-NMR) and the enzymatic activity of the encapsulated lactase. The structural modi¿cations at di¿erent scales were assessed by SAXS. The incorporation of gums as second excipients induces a signi¿cant stabilization in the microstructure not only at the rod scale, but also in the characteristic size and density of alginate dimers (basic units of construction of rods) and the degree of interconnection of rods at a larger scale, improving the performance in terms of lactase activity.This work was supported by the Brazilian Synchrotron Light Laboratory (LNLS, Brazil, proposal SAXS1-20160278), Universidad de Buenos Aires (UBACyT 20020130100610BA), Agencia Nacional de Promocion Cientifica y Tecnologica (ANPCyT PICT 2013 0434 and 2013 1331), CIN-CONICET (PDTS 2015 no 196), and Consejo Nacional de Investigaciones Cientificas y Tecnicas. The author Maria Victoria Traffano-Schiffo wants to thank "Programa para la Formacion de Personal Investigador (FPI)" Pre-doctoral Program of the Universitat Politecnica de Valencia (UPV) for support her PhD studies and also her mobility to Argentina.Traffano-Schiffo, MV.; Castro Giraldez, M.; Fito Suñer, PJ.; Perullini, M.; Santagapita, PR. (2018). Gums induced microstructure stability in Ca(II)-alginate beads containing lactase analyzed by SAXS. Carbohydrate Polymers. 179:402-407. https://doi.org/10.1016/j.carbpol.2017.09.096S40240717

Changes on epicuticular waxes and colour induced by ozone in blueberries

Data of paper: https://doi.org/10.1016/j.jfca.2022.104404ATR-FTIR spectra and color raw data.THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

Isothermal and differential scanning calorimetries to evaluate structural and metabolic alterations of osmo-dehydrated kiwifruit as a function of ripening stage

The effects of osmotic dehydration (OD) on kiwifruit outer pericarp tissue as affected by treatment extent (0\u2013300 min) and raw kiwifruit ripening stage (9 and 14 \ub0Bx) were investigated. Differential scanning calorimetry (DSC) measurements show decomposition of cell wall components (pectins, cellulose and hemi-celluloses). Changes in decomposition parameters (peak temperature lowered and enthalpy increased) were observed related to kiwifruit ripening degree and OD extent increased. Cell wall pectin network disassembly led to the formation of compounds with lower degradation temperature. Raw unripe fruits showed higher \ufb01rmness values and lower compressibility compared to ripe and OD treated fruits. Isothermal calorimetry revealed metabolic heat production of unripe fruits decreasing linearly with the OD extent. Ripe fruit heat production sharply decreased during the \ufb01rst treatment hour, probably as a consequence of membrane integrity loss. Industrial relevance: OD leads to moisture removal and solute uptake in vegetable tissue, providing minimally processed commodities or ingredients for bakery or ice-cream industry. The industrial relevance is the energy-ef\ufb01ciency, since the process does not require water-phase change. OD provokes still unknown collateral alterations on tissue structure and metabolism. The present work applies a new calorimetric approach to evaluate both structure and metabolism changes on kiwifruit as reliant on process extent and raw fruit ripening stage

Osmotic dehydration processing of kiwifruit pericarp tissue studied by means of LF-NMR relaxometry

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

The potential role of isothermal calorimetry in studies of the stability of fresh-cut fruits

Attention is drawn to the feasibility of using high sensitivity isothermal heat conduction calorimetry to study metabolic responses of differently processed and stored fresh-cut fruit. The heat production of endogenous (tissue metabolism during 12 h of analysis at 10 C for kiwifruit and strawberry) and exogenous (microbial growth during 18 d of analysis at 10 C for cantaloupe) biological processes was investigated. Osmotic dehydration of fresh kiwifruit in sucrose solution (61.5 g/L) at different treatment times (30, 60 and 180 min), resulted in metabolic heat production decrease, confirming the progressive cell death induced by osmotic dehydration. Analysis on strawberry slices under two atmospheric conditions (air and innovative modified atmosphere) seemed to confirm the inhibitory effect of N2O on metabolic activity. Cantaloupe samples immersed in three different syrups (SS: sucrose syrup (20 Brix); SS1: SS þ 0.5 g/L ascorbic acid þ 0.5 g/L citric acid; SS2: SS1 þ 0.1 g/L potassium sorbate) showed a stability increase when additives with antimicrobial properties were included. Our findings confirm that isothermal calorimetry provides a versatile and high sensitive tool for conducting fundamental metabolic studies on the effect of different processing operations on the quality and shelf life of fresh-cut fruit and vegetables

Isothermal calorimetry approach for the study of fresh-cut fruit stability

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

Modification of Transverse NMR Relaxation Times and Water Diffusion Coefficients of Kiwifruit Pericarp Tissue Subjected to Osmotic Dehydration

The objective of the present study was to evaluate cellular compartment modifications of kiwifruit (Actinidia deliciosa) outer pericarp tissue caused by osmotic treatment in a 61.5 % sucrose solution, through the quantification of transverse relaxation time (T2) and water self-diffusion coefficient (Dw) obtained by low field nuclear magnetic resonance means. Raw material ripening stage was taken into account as an osmotic dehydration (OD) process variable by analyzing two different kiwifruit groups, low (LB) and high (HB) °Brix. Three T2 values were obtained of about 20, 310, and 1,250 ms, which could be ascribed to the proton populations, located in the cell walls, in the cytoplasm/extracellular space, and in the vacuoles, respectively. According to T2 intensity values, vacuole protons represented between 47 and 60 % of the total kiwifruit protons, for LB and HB kiwifruits, respectively. The leakage of water leading to vacuole shrinkage seemed to cause concentration of solutes, retained by the tonoplast, making the vacuole T2 value decrease along the OD. As expected, the Dw values of raw kiwifruits were lower than the value of the free pure water. The water mobility (and hence Dw), depending on the kiwifruit distinctive cellular structures and solutes, decreased even more during OD due to water loss and sugar gain phenomena. Dw represents an average value of the diffusion coefficient of the whole kiwifruit tissue protons. In order to obtain Dw values specific for each cellular compartment, a multiple component model fitting was also used. According to these results, the vacuole water self-diffusion coefficient (Dw,v) was much higher than Dw