Izzo, Luana
(2018)
Study of milk contaminants and re-evaluation of whey: potential use of dairy by-product in functional food.
[Tesi di dottorato]
| Tipologia del documento: |
Tesi di dottorato
|
| Lingua: |
English |
| Titolo: |
Study of milk contaminants and re-evaluation of whey: potential use of dairy by-product in functional food |
| Autori: |
| Autore | Email |
|---|
| Izzo, Luana | luana.izzo@unina.it |
|
| Data: |
11 Dicembre 2018 |
| Numero di pagine: |
185 |
| Istituzione: |
Università degli Studi di Napoli Federico II |
| Dipartimento: |
Farmacia |
| Dottorato: |
Scienza del farmaco |
| Ciclo di dottorato: |
31 |
| Coordinatore del Corso di dottorato: |
| nome | email |
|---|
| D'Auria, Maria Valeria | madauria@unina.it |
|
| Tutor: |
| nome | email |
|---|
| Ritieni, Alberto | [non definito] |
|
| Data: |
11 Dicembre 2018 |
| Numero di pagine: |
185 |
| Parole chiave: |
whey, milk, orbitrap, antifungal activity, veterinary drug residues, mycotoxins |
| Settori scientifico-disciplinari del MIUR: |
Area 03 - Scienze chimiche > CHIM/10 - Chimica degli alimenti |
[error in script]
[error in script]
| Depositato il: |
19 Dic 2018 12:03 |
| Ultima modifica: |
22 Giu 2020 09:09 |
| URI: |
http://www.fedoa.unina.it/id/eprint/12668 |
Abstract
Milk is the most widely consumed beverage in the world, not counting water, which provides high-quality nutrition to infants, children, and adults, due to its high content of micro- and macronutrients. Despite the benefits that milk provides from a nutritional point of view, it may also be a vehicle of food contaminants, such as mycotoxins and veterinary drug residues (VDs), due to nasty agricultural practices or improper usage of these drugs. In this sense, the first part of my project includes the studies regarding the topics mentioned above.
Hence, a multi-residue method based on a QuEChERS extraction for the simultaneous determination of veterinary drug residues (n=61) and mycotoxins (n=46) in milk was developed by using ultra high performance liquid chromatography coupled with high resolution mass spectrometry (UHPLC Q-Exactive Orbitrap HRMS). The recoveries were in a range of 72-93% at three spiking levels, with repeatability and reproducibility results expressed as relative standard deviations (RSDs) lower than 7% and 14%, respectively. The limits of quantification (LOQs) were in the range of 0.01-50 pg/mL. Matrix effects obtained were in the range of 75-97%. The results obtained from the study showed that none of the analyzed samples (n=56) were contaminated with mycotoxins, whereas the presence of up to seven veterinary drug residues in 50% of analyzed samples was detected (range of 0.007-4.53 ng/mL). None of the analyzed VDs had a concentration level higher than their permitted limits, except for benzylpenicillin procain (4.53 ng/mL). In the post-target screening, 53 contaminants were tentatively identified. Regarding the incidence of mycotoxins, AFM2 contamination was displayed in >70% of analyzed samples. A significant percentage (>80%) has been shown by betamethasone, prednisolone and oxfendazole. Special focus should be paid to the latter, considering that the maximum residue limit permitted in EC 37/2010 is really low, 0.3; 6; 10 μg/Kg, respectively. In addition, other eleven VDs identified in analyzed milk samples are prohibited in milk by the regulation in force (EC 37/2010). From the obtained values seems to be clear the necessity of a continuous monitoring of contaminants in the milk production chain.
The second part of my Ph.D. project was based on the re-evaluation of whey, one of the highest polluting liquid wastes of the dairy industry. Environmental and economic problems associated with food waste have induced industries to reuse these materials in order to minimize food waste. In this sense, I have evaluated the bioactivity of two typologies of whey (freeze-dried cow’s and liquid goat’s whey) after subjecting these by-products to the fermentation process by lactic acid bacteria (Lactobacillus plantarum CECT 220, 221, 223, 748). Antifungal activity performed against 30 mycotoxigenic fungi belonging to the Penicillium, Aspergillus and Fusarium genera has shown a satisfying inhibitory effect. The value of MIC for Aspergillus and Fusarium genera was included in a range from 1.95 to 62.5 g/L whereas for Penicillium genera was included in a range from 3.9 to 125 g/L. The value of MFC was contained between 15.6 and 250 g/L for Aspergillus, 62.5 and 250 g/L for Penicillium, 3.9 and 250 g/L for Fusarium. The antifungal activity could be correlated to the presence of phenolic compounds identified in cell-free-supernatant. Based on previously performed experiments, mycotoxigenic strains of P. expansum and P. brevicompactum were employed for studying the shelf-life improvement of bread.
A valuable increase in the shelf-life was obtained for pita bread prepared with fermented whey. In particular, after the inoculation of bread with Penicillium, a rise of 1-2 and 7-8 days for the two typologies of assayed whey was compared to a positive control. Through a natural contamination, an increase in the preservation period of bread (until the 20th day) was observed.
Regarding the antimicrobial activity, by adding the 1% of freeze-dried fermented whey in bread preparation, a percentage reduction ranged between 12-23% was obtained, whereas with the replacement of 100% of water used in bread preparation with whey fermented by LAB, the percentage of reduction has the highest peak of increase ranged from 42 to 92% for the different typologies of test performed.
In addition, concerning freeze-dried whey, I have evaluated the antioxidant, antihypertensive, and iron binding activity of the permeate, consisting of small bioactive compounds purified on Centricon Amicon with a cut-off of 3 kDa. The results highlighted a radical cation scavenging activity ranging from 1.415 to 2.083 mmol trolox equivalents TE/per kg of dry weight, a percentage of iron binding capacity ranging between 23–55% and a percentage of ACE inhibitory activity ranging between 67–85%. The optimal biological activity was obtained from whey fermented by L. plantarum 220 for all the assays performed, except for the iron chelating activity. These results confirm the interesting use of lactic acid bacteria as a source of new natural preservatives, which can contribute to the maintenance of food quality and safety. The obtained results support the hypothesis of using whey as a functional ingredient to improve food preservation and its potential use in nutraceutical formulation.
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