SHANAKHAT, HINA (2019) Reduction of Mycotoxins by Biological, Enzymatic & Physical Methods and Technological Performance of UVC and Heat Treated Semolina. [Tesi di dottorato]

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Tipologia del documento: Tesi di dottorato
Lingua: English
Titolo: Reduction of Mycotoxins by Biological, Enzymatic & Physical Methods and Technological Performance of UVC and Heat Treated Semolina
Autori:
AutoreEmail
SHANAKHAT, HINAHINA.SHANAKHAT1@GMAIL.COM
Data: 11 Giugno 2019
Numero di pagine: 186
Istituzione: Università degli Studi di Napoli Federico II
Dipartimento: Agraria
Dottorato: Scienze agrarie e agroalimentari
Ciclo di dottorato: 31
Coordinatore del Corso di dottorato:
nomeemail
D'URSO, GUIDOdurso@unina.it
Tutor:
nomeemail
CAVELLA, SILVANA[non definito]
Data: 11 Giugno 2019
Numero di pagine: 186
Parole chiave: Mycotoxins, Biological control, Physical reduction methods, technological performance evaluation
Settori scientifico-disciplinari del MIUR: Area 07 - Scienze agrarie e veterinarie > AGR/15 - Scienze e tecnologie alimentari
Depositato il: 18 Giu 2019 13:24
Ultima modifica: 16 Giu 2020 09:52
URI: http://www.fedoa.unina.it/id/eprint/12739

Abstract

The overall objective of this research is to contribute to the evidences supporting the application of different biological, enzymatic and physical approaches for the reduction of mycotoxins from the cereals and their derivatives. This general aim has been addressed through the accomplishment of three main research topics such as i) the in vitro studies for the degradation of mycotoxins; ii) the evaluation of the physical treatments (UVC and heat) for reduction of mycotoxins and iii) the investigation of physical treatments on the technological performance of semolina, through pasta production and bread baking, attributed to application on industrial scale. New approaches are needed to reduce or eliminate the mycotoxin from food and feed chain. These objectives were achieved making use of a research plan structured according to the following thesis outline. In vitro study of enrichment cultures was conducted for the exploration and characterization of novel bacterial taxa that biotransform DON. Enrichment cultures were developed from the soil samples in minimal media containing chitin and DON 50µg/mL and incubated for longer period of time. DON content was analyzed by gas chromatography mass spectrometer (GC/MS) DON. After three weeks complete transformation of DON was observed in cultures. Microbiome profiling was performed to reveal the reduction in microbial complexity from week 1 to 8 and the screening of pure strains from the cultures were carried out to identify the organism responsible for DON conversion. Such organisms may serve as a source of enzymes or genes involved in detoxification of mycotoxins, which could be useful for decontaminating agricultural commodities (Chapter 2) Another in vitro study of laccase mediated reactions was performed for DON degradation activity in different combinations, in order to find the most appropriate combination. Laccase from Trametes veriscolor mediated by TEMPO was found most interesting to explore. The reactions were performed with enzyme, mediator and DON in Mcllvaine’s buffer solution. GC/MS analysis has revealed the complete transformation of DON into two other metabolites, which were isolated and purified by column chromatography. Characterization of DON metabolites was performed by gas chromatography mass spectrometery (GC/MS), and liquid chromatography mass spectrometery (LC/MS) (Chapter 3). Chapter 4 analyzed some strategies that could be integrated in semolina-based products chains, with the aim of reducing mycotoxin contamination. Thermal treatment and UVC irradiation are selected fotr this research since they are known to be cost-effective techniques, combining a high thermal efficiency with simplicity of application. The effects of heating at 100, 150 and 200°C and UVC irradiation at 254 nm for 15, 30, 60, 120 min applied on semolina for the reduction of mycotoxins and their impact on technological semolina properties was studied. The impact of the most efficient treatments (150°C for 30 min and UVC irradiation for 120 min) were evaluated both on semolina and dough technological properties, such as color, hydration and gluten indices, farinograph and calorimetric parameters and microstructure. Thermal treatment significantly increased hydration of semolina and swelling power; farinograph analyses revealed a marked increase in water absorption and dough development time, and a reduction of dough stability, degree of softening and elasticity compared to the control. Calorimetric analyses showed a significant reduction of both temperature peaks and enthalpy of starch gelatinization, and a decrease of enthalpy for melting of lipids with starch. Scanning electron micrograph images representing the dough microstructure confirmed the occurrence of these changes; UVC-treated samples showed less pronounced changes comparing to the control. The impact of heat and UVC treatments applied for the reduction of mycotoxins was evaluated for technological performance by pasta and bread production. Pasta quality parameters and their micrographs by SEM analysis revealed no significant changes after the studied treatments compared to the control, in particular after UV treatment of semolina, so this treatment can be applied for reduction of mycotoxins without affecting the technological performance of the product, while the impact after heating was marked for some parameters. Technological parameters of bread baking were investigated by the dough consistency at the end of mixing, leavening behaviour of dough and the bread loaf characteristics revealing that until 120°C for 30 min no significant changes were observed in bread quality, while at 150°C a marked reduction of bread performance was shown (Chapter 5). Results from this study could be useful to food companies for the realization of safer semolina-based products such as for baby-food where the limit of mycotoxins fixed by European Commission is lower. In particular, the treatments at 120°C for 30 min can be applied without loss of technogical performance, while the treatment at 150°C could be applied for different types of cereal products, where the process of leavening is not required.

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