1,721,054 research outputs found
NUOVI CAMPI APPLICATIVI DELLA SPETTROSCOPIA NIR PER IL CONTROLLO DI PROCESSO E DI PARAMETRI QUALITATIVI DEI PRODOTTI ALIMENTARI
No full textThe aim of this study was to examine the ability of FT-NIR spectroscopy to monitor the food quality and the process kinetics. In particular this technique was applied to the shelf life evaluation of dairy product, such as packed industrial Ricotta and Crescenza cheese stored at constant temperature for different times. This technique was also used to study the cooking kinetics of milled, parboiled and quick cooking rice samples. FT-NIR spectroscopy was used with some success to investigate macromolecular changes during yeasted bread doughs proofing and bread staling. Comparison of results from FT-NIR spectra, electronic nose, image analysis and calorimetric technique was carried out. FT-NIR was shown to have considerable merit in following chemical-physical modifications involved during a process and thus the potential to be used as on-line method for controlling macromolecular changes during storage, cooking, dough proving and bread staling
Effects of osmo-air dehydration treatments on chemical, antioxidant and morphological characteristics of blueberries
No full textOsmo-air dehydration treatments are widely applied to fruits in order to prolong shelf-life, reduce
packaging and logistic costs, and to improve both sensory and nutritional quality of the end products. In
this work, osmo-air dehydration was applied to blueberries (Vaccinium corymbosum); blanched blueberries
were dipped in sucrose (60 Bx) and fructose/glucose (48.6 Bx) osmotic solutions (aw 1⁄4 0.90) for
24 h, and the osmotic exchanges were determined by mass balances (water loss, solid gain, sugar intake,
changes in total phenolics and anthocyanins). Untreated and infused berries were subsequently air dried
at 70 C to final moisture content of 10e14%, and drying kinetics as well as compositional and
morphological changes of berries were followed in the course of drying. Data show that the osmotic
treatment causes significant losses in the antioxidant components (total phenolics, total and individual
anthocyanins) and in the antioxidant activity. Losses in the antioxidant components also occur in the
course of air drying, with similar kinetics in untreated and infused blueberries. Glucose/fructose infusion
gives better results in terms of morphological changes, with lower shrinkage and wrinkling of the
berries
Tecniche combinate NIRS e Naso Elettronico per lo studio della shelf life di prodotti lattiero-caseari
No full textApplicazione della spettroscopia NIR allo studio on-line della lievitazione di impasti
No full textNegli ultimi anni la spettroscopia NIR si sta dimostrando un metodo valido per la caratterizzazione compositiva e funzionale dei prodotti alimentari e per il monitoraggio on-line di processi, permettendo di analizzare i campioni in modo non distruttivo. In questo lavoro di ricerca la tecnica NIRS è stata utilizzata per controllare in continuo la lievitazione di impasti a differente formulazione.
A tale scopo sono state utilizzate due differenti attrezzature, uno spettrometro basato sul principio della trasformata di Fourier (FT-NIR), ed uno spettrofoto-metro VIS/NIR a monocromatore. Le misure spettroscopiche sono state condotte in continuo utilizzando una fibra ottica posizionata nel centro geometrico del campione e collegata allo strumento. I risultati ottenuti mostrano le potenzialità della tecnica NIRS di identificare una cinetica significativa delle trasformazioni in atto durante i processi, individuando il ruolo di due bande spettrali attribuibili all’assorbimento di acqua e alle trasformazioni dell’amido nella discriminazione dei campioni
Spectroscopic techniques coupled with chemometric tools for the evaluation of light induced oxidation in cheese
No full textAim of this study was to evaluate the application of these methods, combined with chemometric strategies, as non-destructive techniques to evaluate the light induced oxidation in cheese. Semi hard cheese (Edam cheese) was cut in slices with 1 cm thickness and wrapped with clear cling polyethylene film. Samples were stored in a refrigerated industrial display cabinet equipped with fluorescent lights. The light-induced oxidation of samples, stored in the light and in the dark, was monitored by UV-Vis (200-780 nm), FT-NIR (12,500-3,900 cm-1), FT-IR (4,000-700 cm-1) and fluorescence spectroscopy. The overall results have shown that spectroscopic methods are very sensitive to measure the development of light-induced oxidation in cheese products. In particular UV-VIS and fluorescence spectroscopy detected riboflavin decay that appears to be the most light absorbing constituent of cheese
Shelf life evaluation of fresh-cut pineapple using an electronic nose
No full textThe aim of this work was to investigate the applicability of a commercial electronic nose in monitoring freshness of minimally processed fruit (packaged pineapple slices) during storage. The pineapple samples
were taken at the beginning of their commercial life and stored at three different temperatures(4–5, 7–8, and 15–16 ◦C) for 6–10 days. The measurements were performed by applying two analytical
approaches using an electronic nose: a discontinuous method being a series of analyses on samples taken
at various stages of storage, and a continuous method where the headspace around the fruit was automatically
monitored by the electronic nose probe during the preservation of slices in a storage cell. The
results obtained by the discontinuous approach showed that the electronic nose was able to discriminate
between several samples and to monitor the changes in volatile compounds correlated with quality
decay. The second derivative of the transition function, used to interpolate the PC1 score trend versus
the storage time at each temperature, was calculated to estimate the stability time. Results revealed that
fruit freshness was maintained for about 5 days at 5.3 ◦C, 3 days at 8.6 ◦C and 1 day at 15.8 ◦C. Moreover,
from the time–temperature tolerance chart, a Q10 value of 4.48 was derived. These data were confirmed
applying the continuous method: the fruit freshness was maintained for about 5 days at 4 ◦C, 2 days
at 7.6 ◦C and 1 day at 16 ◦C. An interesting future development could be an application in-line of the
continuous electronic nose method
Time-temperature exposure of fresh fish in the commercial chain
No full textFresh fish is a very precious and delicate commodity. Testing/modelling of the shelf life of fresh European Sea bass (Dicentrarchus labrax), with reference to its thermal history in the commercial chain, was approached by means of a new kind of small temperature recording devices, directly placed in the fish meat and/or in the storage rooms. Twenty selected “real” thermal histories were so collected and split into the different steps experienced during the commercial life (storage at manufacturer, delivery, storage in retail cells, exposition in retail counters).
The fish remains at temperatures lower than 1°C during the first steps of the commercialisation and reaches 5°-8°C during the exposition at the sale point: this step is also the longest one (3-5 hours). The obtained data were statistically analysed and plotted on time-temperature exposure probability charts (50%, 75%, 90% probability values were considered). Delivery at the sale points resulted as the critical step because of the poor control of product temperature and the influence of ambient conditions. Collected data were also employed to parameterise the shelf life: a suitable hypothesis was applied to work out the integration of the most probable time-temperature exposure history. Our findings (75% of the cases) showed that the expected shelf life (or “freshness”) just after the purchase of fresh fish was 60% of the whole one. This condition can be related to an integration average temperature of 4°C, considering 2 days of commercialisation time. Furthermore, our results showed that freshness can be maintained for 1-2 days more during the storage at home. The average exposure temperature could be then reduced by 1-2°C with a joined effort (manufacturer, sale point management, consumer advertising) thus extending the fresh fish shelf life up to 4-5 days
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