Al-Asmar, Asmaa (2020) Nanoreinforced and Crosslinked Hydrocolloid Films to Prevent the Formation of Toxic Products During Food Cooking and to Extend Food Shelf-Life. [Tesi di dottorato]

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Tipologia del documento:	Tesi di dottorato
Lingua:	English
Titolo:	Nanoreinforced and Crosslinked Hydrocolloid Films to Prevent the Formation of Toxic Products During Food Cooking and to Extend Food Shelf-Life
Autori:	Autore Email Al-Asmar, Asmaa asmaa.alasmar@unina.it
Data:	10 Marzo 2020
Numero di pagine:	194
Istituzione:	Università degli Studi di Napoli Federico II
Dipartimento:	Scienze Chimiche
Dottorato:	Biotecnologie
Ciclo di dottorato:	32
Coordinatore del Corso di dottorato:	nome email Moracci, Marco marco.moracci@unina.it
Tutor:	nome email Mariniello, Loredana [non definito]
Data:	10 Marzo 2020
Numero di pagine:	194
Parole chiave:	Nanoparticles, Acrylamide, Edible Coatings
Settori scientifico-disciplinari del MIUR:	Area 05 - Scienze biologiche > BIO/10 - Biochimica
Depositato il:	06 Apr 2020 09:30
Ultima modifica:	10 Nov 2021 10:06
URI:	http://www.fedoa.unina.it/id/eprint/13058

Abstract

Food heating or cooking is one of the oldest method for food treatment that can be used to increase the food shelf-life and improve the palatability, aroma, taste, appearance and texture into the final product. Moreover, cooking provides safe food to the consumer by inactivation of pathogenic organisms/microorganisms, toxins, or enzymes. However, heating of foods might also have undesirable consequences, e.g., the loss of nutrients and vitamins. Thermal treatment of food also produces harmful substances and toxic compounds like Maillard reaction products, furan, heterocyclic amines, acrylamide, acrolein, and trans fatty acids. These compounds are considered as carcinogenic, mutagenic, genotoxic, and teratogenic and are a concern for human health. During this project we focused on acrylamide (ACR), a compound highly soluble in water, about which heightened concerns regarding its exposure arose in 2002 when Swedish researchers discovered its formation in certain foods, when they were prepared at temperatures above 120ºC, and in the presence of low moisture. Its formation, at least in part, is due to the Maillard reaction in foods rich in free asparagines and reducing sugars. According to the European Food Safety Authority (EFSA), ACR forms in numerous baked and/or fried foods rich in free asparagine, including French fries, potato crisps, breads, biscuits, and coffee (roasted beans). ACR is also known to be present in cigarette smoke. The EFSA report in 2015 mentioned that rats and mice exposed to ACR have shown some signs of developmental toxicity, increased incidence of skeletal variations, slightly impaired body weight gain, histological changes in the central nervous system, and some neurobehavioral effects. Different fried foods (French fries, falafel and kobbah) were studied during this project to reduce ACR and oil content, with the aim of producing healthier fried foods. Hydrocolloid coatings were containing pectin (PEC), chitosan (CH), or grass pea flour (GPF) enzymatically crosslinked by means of transglutaminase (TGase) or reinforced with mesoporous silica nanoparticles (MSN) or chitosan nanoparticles (CH-NP), were used to achieve the objectives. In French fries, GPF treated or not by TGase, CH, and PEC hydrocolloid coating solutions were used to coat the potatoes before frying. ACR, water retention as well as oil content were evaluated. In addition, the Daily Intake (DI) and Margin of Exposure (MOE) were calculated to estimate variations in risk assessment by applying coating solutions before frying. Our results showed that the highest ACR content was detected in the control sample, reaching a value of 2089 μg kgˉ¹. Hydrocolloid coating solutions were demonstrated to be an effective way to reduce ACR formation, with the percentage of ACR reduction equal to 48% for PEC, 38% for CH, 37% for GPF + TGase, and 31% for GPF, respectively. The MOE value for coated French fries increased, resulting higher safety level to diminish carcinogenic risk. Moreover, the tailored coatings were effective in reducing oil uptake. Falafel is traditional street food in Middle Eastern. It is a deep fried ball made of spiced fava beans and/or chickpeas. In this project TGase (5 or 20U/g of chickpea proteins) was added on falafel dough and the effect of the enzyme was investigated. Afterwards, the resulted falafel balls were either treated or not by dipping them into PEC coating solution. ACR, oil and water content were, hence, evaluated. Texture profile analyses (TPA) and sensory evaluation performed by trained Palestinian panellists were carried out. Moreover, in vitro gastric digestion experiments were also performed to study the effect of the enzyme and coatings on falafel digestibility. The ACR content was reduced by 10.8% and by 34.4% in the samples prepared with 5 and 20U TGase/g, respectively. In PEC-coated samples, the reduction of ACR was equal 14 to 59.3%, 65.3% and 84.5%, in falafel balls prepared either without TGase or containing 5U or 20U of the enzyme, respectively. However, TGase treatment did not affect oil content, while the PEC coating reduced oil uptake by 23.5%. No difference was observed between the control sample and the one dipped in PEC in regard to TPA while these properties changed in samples prepared with the enzyme. Panellists accepted falafel coated by PEC solution, ever better than the traditional ones, while a negative score was obtained by TGase-containing falafel. The digestion studies demonstrated that the falafel prepared in the presence of TGase was efficiently digested in the in vitro gastric environment. Kobbah is a food typical in Middle Eastern countries but also used as an ethnic dish. It was prepared according to traditional recipe and then dipped using different solutions. The first set of dipping solutions was GPF-based and containing only GPF (GPF samples) reinforced by means of TGase (GPF+TGase samples) and/or by means of mesoporous nanoparticles (MSN) (GPF+MSN samples and GPF+MSN+TGase samples). Some GPF-containing samples were prepared also using, as nanoreinforcement, the (CH-NP), (GFP+CH-NP samples and GFP+CH-NP+TGase samples). The second set of dipping solutions was PEC-based reinforced by means of MSN (PEC+MSN samples) or CH-NP (PEC+CH-NP samples). All hydrocolloid-based materials, used to coat kobbah, were effective in provoking a significant reduction in ACR and oil content comparing to the controls. The highest reduction rates were obtained using both PEC+MSN and PEC+CH-NP samples. However, also GPF+MSN+TGase and GPF+CH-NP+TGase samples were responsible for ACR reduction (41.0% or 47.5% respectively) in comparison to the nanoreinforced GPF prepared in the absence of the enzyme. The results indicated that the water content was significantly increased after coating the kobbah by different coating solutions. Nanoreinforcement of the coating solutions by either MSN or CH-NP for both GPF-based and PEC-based coatings, showed the ability of increasing the water retention inside the kobbah. Water retention in these samples was significantly higher than retention exhibited from samples coated with GPF-based solution or PEC-based solutions. PEC solutions, set up in the presence and in the absence of glycerol (GLY), were used to prepare bioplastics reinforced by MSN. Nanoparticles reduced significantly the particle size, and had no effect on the Zeta potential of PEC solutions. Mechanical characterization studies demonstrate that PEC containing MSN films exhibit a slightly increase in tensile strength and a significantly decrease in the Young’s modulus in comparison to films made of only PEC. However, elongation at the break increased in the PEC-MSN films cast in the presence of GLY, while both Young’s modulus and tensile strength were reduced. Moreover, nanoparticles were able to reduce the barrier properties of PEC films prepared with or without GLY, whereas positively affected the thermal stability of PEC films and the seal strength. The 0.6% PEC films reinforced or not with 3% nanoparticles in the presence of 30% GLY were used to wrap strawberries in order to extend the fruit shelf-life, over a period of eighty days, by improving their physicochemical properties, thus suggesting a possible use of these materials as novel bioplastics to protect fruit.

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