Βελτιστοποίηση της διεργασίας ωσμωτικής αφυδάτωσης και εδώδιμης επικάλυψης για την ανάπτυξη σμέουρων με αυξημένη διάρκεια ζωής και ανώτερα ποιοτικά χαρακτηριστικά

Νικολάου, Μαρία Μαγδαληνή; Nikolaou, Maria Magdalini

dc.contributor.author	Νικολάου, Μαρία Μαγδαληνή	el
dc.contributor.author	Nikolaou, Maria Magdalini	en
dc.date.accessioned	2022-01-17T09:19:33Z
dc.date.available	2022-01-17T09:19:33Z
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/54326
dc.identifier.uri	http://dx.doi.org/10.26240/heal.ntua.22024
dc.rights	Default License
dc.subject	Ωσμωτική αφυδάτωση	el
dc.subject	Σμέουρα	el
dc.subject	Εδώδιμη επικάλυψη	el
dc.subject	Osmotic dehydration	en
dc.subject	Raspberries edible	en
dc.subject	Coating	en
dc.title	Βελτιστοποίηση της διεργασίας ωσμωτικής αφυδάτωσης και εδώδιμης επικάλυψης για την ανάπτυξη σμέουρων με αυξημένη διάρκεια ζωής και ανώτερα ποιοτικά χαρακτηριστικά	el
heal.type	bachelorThesis
heal.generalDescription	Πειραματική εργασία που εξετάζει την βελτιστοποίηση της διεργασίας ωσμωτικής αφυδάτωσης και εδώδιμης επικάλυψης για την ανάπτυξη σμέουρων με αυξημένη διάρκεια ζωής και ανώτερα ποιοτικά χαρακτηριστικά	el
heal.classification	Food engineering	en
heal.language	el
heal.access	free
heal.recordProvider	ntua	el
heal.publicationDate	2021-06-28
heal.abstract	It is true that consumers nowadays require healthy foods, which are limited or slightly processed but can retain their sensory characteristics, similar to the fresh foods. In order to determine how healthy and nutritious a food is, the amount of bioactive ingredients is examined, such as antioxidants, phenolic compounds, vitamins, sterols and flavonoids. Berries, such as raspberries, are fruits with a very high nutritional value and content of bioactive ingredients such as the above. That is something that has attracted the interest of consumers and their demand is growing. Nevertheless, their seasonality, combined with their sensitivity during transport and storage, is a barrier to the availability of fresh raspberries. For this reason, it is considered particularly useful to dehydrate and process the fruits, in order to increase their shelf life, and therefore make them available all year round. The purpose of this dissertation is the development of raspberries with increased shelf life and improved quality characteristics using mild processing methods. The methods used were osmotic dehydration in combination with the application of edible coating. Osmotic dehydration was chosen as a treatment method because it is a mild and economical method, which leads to products that retain their sensory characteristics and nutrients. Alternative osmotic agents have been studied, such as concentrated apple juice and its substitution by pectin as an alternative sweetener. The parameters of the treatment examined were the osmotic agent (sucrose, glycerol, apple juice, apple juice in combination with pectin and apple juice in combination with glycerol), the concentration of the osmotic solution and the duration of osmotic treatment (0.17 to 24 h). The solid to solution ratio remained constant at 1: 5. Process efficiency is assessed by determining the moisture loss and solids uptake of raspberries during osmotic treatment. The evaluation of the process parameters showed that the increase of temperature and duration of the osmotic dehydration lead to increased moisture loss and solids uptake. The same was observed for the increase of the concentration of the osmotic agent. Apple juice resulted in a moisture loss of 46%, while a combination of apple juice and glycerol as an osmotic agent resulted in a moisture loss of 47%. Sucrose in optimal conditions led to a corresponding rate of 41% and glycerol to 48%. Solid uptake showed the highest values in osmotic dehydration with glycerol. The total soluble solids and their total acidity after osmotic dehydration were evaluated for the dehydrated products, resulting from the optimal osmotic dehydration conditions (osmotic medium, concentration, duration). Total soluble solids appeared reduced for each osmotic agent, while total acidity appeared to remain stable with the exception of glycerol which led to a decrease in total acidity and apple juice which led to an increase. In order to improve the shelf life of osmotically dehydrated samples, an edible coating of pectin as well as aloe (Aloe Vera) was applied. The coated samples were evaluated for their quality characteristics (color, weight loss, total soluble solids, total acidity) and their antioxidant activity after storage for 7 days. In addition, the sensory characteristics of osmotically dehydrated samples were evaluated before and after the application of edible aloe vera coating. It was found that the ability of the coated samples to retain the color depended on the osmotic agent that had preceded, with pectin giving better results in combination with sucrose and apple juice and aloe giving better results in combination with glycerol and apple juice-glycerol. The weight loss was lower for the samples that underwent osmotic dehydration with pectin-coated sucrose and those that underwent 8 osmotic dehydration with apple juice - glycerol and coated with aloe. Total soluble solids decreased slightly for most osmotic agents and coatings. Finally, all samples showed a decrease in acidity during storage. In terms of antioxidant activity, the largest increase is found in samples that are osmotically dehydrated with glycerol and coated with pectin and aloe. The sensory evaluation showed as best the uncoated sample dehydrated with apple juice, with the aloe-coated samples dehydrated with apple juice and apple juice-glycerol following. Based on the above, the solution of apple juice and glycerol in combination with aloe coating as well as the osmotic solution of glycerol with aloe coating are found to be the optimal combinations of osmotic agent and coating. These conditions were selected as they show effective moisture loss during osmotic dehydration, maintain quality characteristics during storage and improve the antioxidant activity of the sample	en
heal.abstract	It is true that consumers nowadays require healthy foods, which are limited or slightly processed but can retain their sensory characteristics, similar to the fresh foods. In order to determine how healthy and nutritious a food is, the amount of bioactive ingredients is examined, such as antioxidants, phenolic compounds, vitamins, sterols and flavonoids. Berries, such as raspberries, are fruits with a very high nutritional value and content of bioactive ingredients such as the above. That is something that has attracted the interest of consumers and their demand is growing. Nevertheless, their seasonality, combined with their sensitivity during transport and storage, is a barrier to the availability of fresh raspberries. For this reason, it is considered particularly useful to dehydrate and process the fruits, in order to increase their shelf life, and therefore make them available all year round. The purpose of this dissertation is the development of raspberries with increased shelf life and improved quality characteristics using mild processing methods. The methods used were osmotic dehydration in combination with the application of edible coating. Osmotic dehydration was chosen as a treatment method because it is a mild and economical method, which leads to products that retain their sensory characteristics and nutrients. Alternative osmotic agents have been studied, such as concentrated apple juice and its substitution by pectin as an alternative sweetener. The parameters of the treatment examined were the osmotic agent (sucrose, glycerol, apple juice, apple juice in combination with pectin and apple juice in combination with glycerol), the concentration of the osmotic solution and the duration of osmotic treatment (0.17 to 24 h). The solid to solution ratio remained constant at 1: 5. Process efficiency is assessed by determining the moisture loss and solids uptake of raspberries during osmotic treatment. The evaluation of the process parameters showed that the increase of temperature and duration of the osmotic dehydration lead to increased moisture loss and solids uptake. The same was observed for the increase of the concentration of the osmotic agent. Apple juice resulted in a moisture loss of 46%, while a combination of apple juice and glycerol as an osmotic agent resulted in a moisture loss of 47%. Sucrose in optimal conditions led to a corresponding rate of 41% and glycerol to 48%. Solid uptake showed the highest values in osmotic dehydration with glycerol. The total soluble solids and their total acidity after osmotic dehydration were evaluated for the dehydrated products, resulting from the optimal osmotic dehydration conditions (osmotic medium, concentration, duration). Total soluble solids appeared reduced for each osmotic agent, while total acidity appeared to remain stable with the exception of glycerol which led to a decrease in total acidity and apple juice which led to an increase. In order to improve the shelf life of osmotically dehydrated samples, an edible coating of pectin as well as aloe (Aloe Vera) was applied. The coated samples were evaluated for their quality characteristics (color, weight loss, total soluble solids, total acidity) and their antioxidant activity after storage for 7 days. In addition, the sensory characteristics of osmotically dehydrated samples were evaluated before and after the application of edible aloe vera coating. It was found that the ability of the coated samples to retain the color depended on the osmotic agent that had preceded, with pectin giving better results in combination with sucrose and apple juice and aloe giving better results in combination with glycerol and apple juice-glycerol. The weight loss was lower for the samples that underwent osmotic dehydration with pectin-coated sucrose and those that underwent 8 osmotic dehydration with apple juice - glycerol and coated with aloe. Total soluble solids decreased slightly for most osmotic agents and coatings. Finally, all samples showed a decrease in acidity during storage. In terms of antioxidant activity, the largest increase is found in samples that are osmotically dehydrated with glycerol and coated with pectin and aloe. The sensory evaluation showed as best the uncoated sample dehydrated with apple juice, with the aloe-coated samples dehydrated with apple juice and apple juice-glycerol following. Based on the above, the solution of apple juice and glycerol in combination with aloe coating as well as the osmotic solution of glycerol with aloe coating are found to be the optimal combinations of osmotic agent and coating. These conditions were selected as they show effective moisture loss during osmotic dehydration, maintain quality characteristics during storage and improve the antioxidant activity of the sample.	en
heal.advisorName	Κροκίδα, Μαγδαληνή	el
heal.committeeMemberName	Παππά, Αθηνά	el
heal.committeeMemberName	Κροκίδα, Μαγδαληνή	el
heal.committeeMemberName	Τσιβιλής, Σωτήριος	el
heal.committeeMemberName	Krokida, Magdalini	en
heal.academicPublisher	Εθνικό Μετσόβιο Πολυτεχνείο. Σχολή Χημικών Μηχανικών. Τομέας Ανάλυσης, Σχεδιασμού και Ανάπτυξης Διεργασιών και Συστημάτων (ΙΙ). Εργαστήριο Σχεδιασμού και Ανάλυσης Διεργασιών	el
heal.academicPublisherID	ntua
heal.numberOfPages	118 σ.	el
heal.fullTextAvailability	false