Nicolò Dellarosa

Calcium and ascorbic acid affect cellular structure and water mobility in apple tissue during osmotic dehydration in sucrose solutions

The effects of the addition of calcium lactate and ascorbic acid to sucrose osmotic solutions on cell viability and microstructure of apple tissue were studied. In addition, water distribution and mobility modification of the different cellular compartments were observed. Fluorescence microscopy, light microscopy and time domain nuclear magnetic resonance (TD-NMR) were respectively used to evaluate cell viability and microstructural changes during osmotic dehydration. Tissues treated in a sucrose-calcium lactate-ascorbic acid solution did not show viability. Calcium lactate had some effects on cell walls and membranes. Sucrose solution visibly preserved the protoplast viability and slightly influenced the water distribution within the apple tissue, as highlighted by TD-NMR, which showed higher proton intensity in the vacuoles and lower intensity in cytoplasm-free spaces compared to other treatments. The presence of ascorbic acid enhanced calcium impregnation, which was associated with permeability changes of the cellular wall and membranes.

A first step towards a consensus static in vitro model for simulating full-term infant digestion

In vitro alternatives to clinical trials are used for studying human food digestion. For simulating infant digestion, only a few models, lacking physiological relevance, are available. Thanks to an extensive literature review of the in vivo infant digestive conditions, a gastrointestinal static in vitro model was developed for infants born at term and aged 28days. The model was applied to the digestion of a commercial infant formula. Kinetics of digestion, as well as the structural evolution, were compared with those obtained while submitting the same formula to the adult international consensus protocol of in vitro static digestion. The kinetics of proteolysis and lipolysis differed according to the physiological stage resulting mainly from the reduced level of enzymes and bile salts, as well as the higher gastric pH in the infant model. This in vitro static model of infant digestion is of interest for scientists, food or pharmaceutical manufacturers.

The influence of carrier material on some physical and structural properties of carrot juice microcapsules

This study investigates the effect of carrier type on the physical and structural properties of microcapsules of pure carrot juice. Low-crystallised maltodextrin (MD), gum arabic (GA), mixtures of MD and GA (1:1; 2:1; 3:1) and whey protein isolate (WPI) were used as carriers. Microencapsulation was carried out in a spray-drier at inlet air temperature of 160°C. Powders were investigated for dry matter, water activity, diameter, carotene content and hygroscopicity. In addition, differential scanning calorimetry (DSC) and time domain nuclear magnetic resonance (TD-NMR) were applied to analyse microcapsules glass transition temperature (Tg). Carrot powders with GA used as a carrier material resulted in better carotenoids retention and higher stability of powders in terms of higher Tg, lower aw and good hygroscopic properties. However, all powders showed a low aw (below 0.26) and high dry matter content (98-99%) indicating a good potential for protection of microencapsulated carotenoids during the storage.

The impact of pulsed electric fields and ultrasound on water distribution and loss in mushrooms stalks

Pulsed electric fields (PEF) and ultrasound (US) are promising innovative technologies with the potential to increase mass transfer when combined with further processes which in turn can provide potential benefits in the recovery of valuable compounds from food by-products. To provide evidence of the mechanism of mass transfer enhancement, the present study assessed the impact of PEF and US treatments, applied individually and in combination, at low and high temperatures, on the tissue microstructure of mushroom stalks. Different indices such as quantitative water redistribution, water loss and qualitative release of compounds were evaluated. The combination of these physical methods demonstrated that PEF redistributed a greater proportion of intracellular water into extracellular spaces than US. However, the application of high temperature treatments alone showed an even greater proportion of intracellular water migration compared to PEF. When PEF was combined with US at low temperatures the difference was not significant.

Effect of freezing on microstructure and degree of syneresis in differently formulated fruit fillings

This study describes the syneresis and its effect on microstructure in fruit fillings within a wide range of the total soluble solids content and with or without hydrocolloids upon freezing. Linear models showed the relevance of the addition of pectin and gellan gum to fillings to prevent syneresis, increasing the water-holding capacity especially after freezing. Microstructural experiments by means of NMR spin-spin relaxometry combined with fluorescence microscopy allowed to observe that the continuous hydrocolloid gel, containing the dispersed solution of native fruit parts with the addition of inulin and sugars, changed its structure/distribution according to the amount of each ingredient and due to the freezing process. Relaxometry results confirmed that hydrocolloids strength was correlated (R(2)>0.92) with water-holding capacity, due to a relationship between the signal given by the water chemically exchanging with biopolymers, and the changes in the degree of syneresis.

Urine metabolome in women with Chlamydia trachomatis infection

The aim of this study was to characterize the urine metabolome of women with Chlamydia trachomatis (CT) uro-genital infection (n = 21), comparing it with a group of CT-negative subjects (n = 98). By means of a proton-based nuclear magnetic resonance (1H-NMR) spectroscopy, we detected and quantified the urine metabolites of a cohort of 119 pre-menopausal Caucasian women, attending a STI Outpatients Clinic in Italy. In case of a CT positive result, CT molecular genotyping was performed by omp1 gene semi-nested PCR followed by RFLP analysis. We were able to identify several metabolites whose concentrations were significantly higher in the urine samples of CT-positive subjects, including sucrose, mannitol, pyruvate and lactate. In contrast, higher urinary levels of acetone represented the main feature of CT-negative women. These results were not influenced by the age of patients nor by the CT serovars (D, E, F, G, K) responsible of the urethral infections. Since the presence of sugars can increase the stability of chlamydial proteins, higher levels of sucrose and mannitol in the urethral lumen, related to a higher sugar consumption, could have favoured CT infection acquisition or could have been of aid for the bacterial viability. Peculiar dietary habits of the subjects enrolled, in term of type and amount of food consumed, could probably explain these findings. Lactate and pyruvate could result from CT-induced immunopathology, as a product of the inflammatory microenvironment. Further studies are needed to understand the potential role of these metabolites in the pathogenesis of CT infection, as well as their diagnostic/prognostic use.

Water diffusion to assess meat microstructure

In the quest for setting up rapid methods to evaluate water retention ability of meat microstructures, time domain nuclear magnetic resonance (TD-NMR) has gained a prominent role, due to the possibility to observe water located outside the myofibrils, easily lost upon storage or cooking. Diffusion weighted signals could be used to monitor the shape and dimension of the pores in which water is confined, thus boosting the information offered by TD-NMR. The work outlines a parsimonious model to describe relative abundance and diffusion coefficient of intra and extra myofibrillar water populations, exchange rate between them, diameter of the myofibrillar cells. To test our model, we registered diffusion and T2 weighted NMR signals at 20MHz on fresh meat from pectoralis major muscle of 100days old female turkey. We then purposely altered water distribution and myofibrils shape by means of freezing. The model predicted nicely the consequences of the imposed modifications.

Effect of Pulsed Electric Fields on Water Distribution in Apple Tissue as Monitored by NMR Relaxometry

Pulsed electric fields (PEF) technology is a promising innovative non-thermal process to improve mass transfer in food sector. PEF treatments induce a partial cell membranes electroporation which extent depends on electric field strength, number, duration and shape of the pulses and application time. The present work aimed at highlighting the effect of the application of PEF on mass transfer phenomena in apple parenchyma tissue, by evaluating the water distribution across cell compartments by means of NMR relaxometry. Pulsed electric fields treatments were carried out using near-rectangular shaped pulses with fixed 100 μs pulse width and 10 ms repetition time at three different specific voltage (100, 250 and 400 V cm− 1) and two different pulse number series (n=20 and n=60).