Search results for "Past"
showing 10 items of 931 documents
Bioaccessibility of Deoxynivalenol and its natural co-occurrence with Ochratoxin A and Aflatoxin B1 in Italian commercial pasta
2012
Abstract Cereals products for direct human consumption are rarely contaminated by moulds, unlike raw materials, which are often infected, either in the field or during storage. In this study, 27 samples of dried pasta characterised by size, packaging and marketing intended for young children consumption were collected and analysed by liquid chromatography (LC) and liquid chromatography–tandem mass spectrometry (LC–MS/MS) for Deoxynivalenol (DON), Ochratoxin A (OTA) and Aflatoxin B 1 (AFB 1 ) determination. The samples that showed the highest amounts of one of the mycotoxins were cooked for 10 min, digested with an in vitro gastrointestinal protocol and bioaccessibility values were calculate…
Towards practical reflexivity in online discussion groups
2017
This paper continues the discussion about student-driven, interactive learning activities in higher education. Using object-oriented activity theory, the article explores the relational aspects of reflexive practice as demonstrated in five online discussions groups to develop students’ conceptual understanding. The purpose of the research is to describe both the process of reflection during online interaction and how practical engagement with the discipline is supported through pedagogical guidance. The students wrote short texts on the practice of health promotion ethics and discussed their perspectives in relation to theory and research. The analysis proved the importance of structural de…
Guidance Provided by Teacher and Simulation for Inquiry-Based Learning: a Case Study
2016
Current research indicates that inquiry-based learning should be guided in order to achieve optimal learning outcomes. The need for guidance is even greater when simulations are used because of their high information content and the difficulty of extracting information from them. Previous research on guidance for learning with simulations has concentrated on guidance provided by the simulation. Little research has been done on the role of the teacher in guiding learners with inquiry-based activities using simulations. This descriptive study focuses on guidance provided during small group investigations; pre-service teachers (n = 8) guided third and fifth graders using a particular simulatio…
Ascorbic acid stability during refrigerated storage of orange–carrot juice treated by high pulsed electric field and comparison with pasteurized juice
2006
Abstract The degradation kinetics of ascorbic acid was determined in orange–carrot juice treated by PEF in order to establish its shelf life. Different electric field intensities (25, 30, 35, and 40 kV/cm) and different treatment times (from 30 to 340 μs) were studied. The ascorbic acid degradation rate (k) obtained was −0.009 ± 0.0008 μs−1, −0.0140 ± 0.0009 μs−1, −0.0220 ± 0.0023 μs−1 and −0.0187 ± 0.0049 μs−1 for fields of 25, 30, 35, and 40 kV/cm, respectively. The treatment selected was 25 kV/cm. The shelf life of the orange–carrot juice treated by pulses at 25 kV/cm for two times (280 μs and 330 μs) was compared with a heat-treated juice (98 °C, 21 s) kept in refrigerated storage at 2 …
Ascorbic acid in orange juice–milk beverage treated by high intensity pulsed electric fields and its stability during storage
2010
Abstract The degradation of ascorbic acid was determined in a ready-to-drink orange juice–milk beverage treated by high intensity pulsed electric fields (PEF). The effects of PEF treatment were compared to those of heat pasteurization (90 oC, 20 s). Four electric field strengths (15, 25, 35, 40 kV/cm) and six treatment times for each field (from 40 µs to 700 µs) were studied. Ascorbic acid degradation was adjusted to an exponential model. The obtained ascorbic acid degradation rate constants (kE) were − 0.11·10− 3 ± 0.03·10− 3 μs− 1, − 0.23·10− 3 ± 0.07·10− 3 μs− 1, − 0.42·10− 3 ± 0.09·10− 3 μs− 1 and − 0.60·10− 3 ± 0.06·10− 3 μs− 1 for field strengths of 15, 25, 35 and 40 kV/cm, respective…
PCR-fingerprinting and RAPD approaches for tracing the source of yeast contamination in a carbonated orange juice production chain.
2005
Aims: To investigate the sort and the origin of the contamination of a packed fruit juice. Methods and Results: Fifty-eight yeast isolates were collected in a survey of two different visits to a carbonated orange juice factory. In each visit, samples were collected, six times, from seven points in the production chain. For each visit, no significant differences were observed among the yeast average values obtained in the control points considered. The random amplified polymorphic DNA (RAPD) with primer P24 and the PCR-fingerprinting with the microsatellites primers (GTG)5 and (GAC)5 were used, in order to discriminate the isolates, rendering 29 composite profiles; the most frequent one (24/…
Color of orange juice treated by High Intensity Pulsed Electric Fields during refrigerated storage and comparison with pasteurized juice
2008
Abstract High Intensity Pulsed Electric Field (HIPEF) is one of the nonthermal minimal processing technologies interesting for scientists and food industry as a new, alternative (preservation) process for liquid food. We have evaluated the effect on color, browning and hydroxymethylfurfural (HMF) of a pasteurized orange juice and the same orange juice treated by HIPEF, during 7 weeks stored in refrigeration at 2 °C and 10 °C. Pasteurized orange juice presents greater yellow tendency ( b ∗ ) and less red tendency ( a ∗ ) than the untreated orange juice, while HIPEF orange juice presents a coloration more similar to the untreated orange juice. Color variations (Δ E ) during storage are greate…
Effects of thermal treatments on pectinesterase activity determined in blood oranges juices
2005
Abstract The citrus processing industry aims to maintain turbidity and attractive colour of the juice obtained from Sicilian blood oranges. Nevertheless, the presence of pectinesterase (PE, E.C. 3.1.1.11) causes the loss of these peculiar characteristics, due to precipitation of colloids and very fine pieces of pulp in suspension, with negative effects on colour and clarification of the juices. This study compares total PE activity of Sicilian blood oranges ( Sanguinello , Moro , Tarocco ) with the blonde cultivar Navel , checking enzyme stability with various pasteurisation times and temperatures conditions. Decimal reduction time and temperature ( D and z ) as well as the kinetic constant…
Anteroxanthin concentration during refrigerated storage in orange juice treated by PEF
2009
Pulsed Electric Field (PEF) processing inactivates microorganisms without significant adverse effects on flavor and nutrients. In this work was studied the transformations of antheraxanthin and mutatoxanthin when natural orange juice is treated by pasteurisation (90°C, 20 s) or PEF (30 kV/cm, 100 µs), and also its evolution during seven weeks of storage in refrigeration at two different temperatures (2°C and 10°C). The results showed that antheraxanthin concentration decreased during the storage. The decrease was greater in the untreated, pasteurised and PEF-treated orange juices stored at 10°C and this carotenoid was not detected from the 6 th week onwards. The same result was observed in …
Carotenoid Profile Modification during Refrigerated Storage in Untreated and Pasteurized Orange Juice and Orange Juice Treated with High-Intensity Pu…
2006
A comparative study was made of the evolution and modification of various carotenoids and vitamin A in untreated orange juice, pasteurized orange juice (90 degrees C, 20 s), and orange juice processed with high-intensity pulsed electric fields (HIPEF) (30 kV/cm, 100 micros), during 7 weeks of storage at 2 and 10 degrees C. The concentration of total carotenoids in the untreated juice decreased by 12.6% when the juice was pasteurized, whereas the decrease was only 6.7% when the juice was treated with HIPEF. Vitamin A was greatest in the untreated orange juice, followed by orange juice treated with HIPEF (decrease of 7.52%) and, last, pasteurized orange juice (decrease of 15.62%). The decreas…