Utjecaj ultrazvučne obrade na nutritivnu vrijednost soka od jagode

master's thesis

• Title (english): Influence of ultrasonic treatment on nutritional value of strawberry juice
• Author: Luka Jasenko
• Mentor: Jana Šic Žlabur (mentor)
• Committee member: Jana Šic Žlabur (predsjednik povjerenstva)
• Committee member: Sandra Voća (član povjerenstva)
• Committee member: Boris Duralija (član povjerenstva)
• Granter: University of Zagreb; Faculty of Agriculture; (Sustainable Technologies and Renewable Energy Sources); Zagreb
• Defense date and country: 2019-09-25, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Agronomy

Abstract

Toplinska obrada, u usporedbi s drugim metodama konzerviranja hrane, ima važnu prednost u osiguravanju sigurnosti hrane i dugom čuvanju zbog destruktivnog učinka na enzime i mikroorganizme. Međutim, nespecifični učinak topline može uzrokovati smanjenje nutritivne i senzorne kvalitete hrane i narušiti njezina funkcionalna svojstva. Kako bi se izbjegli neželjeni učinci topline, u procesiranju hrane počinju se koristiti neinvazivni postupci, a koji prije svega osiguravaju očuvanje nutritivne... More kvalitete proizvoda. Jedna od spomenutih tehnika je i ultrazvuk koja se klasificira kao netoplinska metoda. U prehrambenoj tehnologiji koristi se ultrazvuk visokog intenziteta (u rasponu od 10-1000 W/cm² i frekvencijom 20-100 kHz), a koji uslijed djelovanja glavnog mehanizma kavitacije uzrokuje mehaničke, fizikalne i kemijske promjene. Cilj ovog rada bio je utvrditi utjecaj toplinske obrade i ultrazvučnog tretmana na nutritivnu kvalitetu soka od jagode. U svrhu konvencionalne toplinske obrade soka od jagode proveden je postupak pasterizacije pri dvije temperature obrade (60 °C i 80 °C) u vremenskom trajanju od 15 i 35 minuta, dok je ultrazvučna obrada soka provedena u ultrazvučnoj kupelji (35 kHz i 40 W) pri sobnoj temperaturi, te temperaturi kupelji od 60 °C i 80 °C i u vremenskom trajanju od 15 i 35 minuta. Od parametara nutritivne vrijednosti soka od jagode analizirana su: fizikalno kemijska svojstva (sadrţaj suhe tvari, topljive suhe tvari, ukupne kiseline, pH vrijednost i električna provodljivost); sadrţaj bioaktivnih spojeva (vitamina C, ukupnih fenola, flavonoida, neflavonoida, antocijana), te antioksidacijski kapacitet. Temeljem dobivenih rezultata, dokazano je kako ultrazvuk nije značajno utjecao na većinu fizikalno-kemijskih svojstava soka jagode, osim na sadržaj ukupnih kiselina. Pasterizacija je utjecala na povećanje sadržaja suhe tvari i električne provodljivosti. Što se tiče sadržaja istraživanih specijaliziranih metabolita, ultrazvuk je utjecao na povećanje sadržaja vitamina C, ukupnih fenola, ukupnih antocijana i antioksidacijskog kapaciteta. Na kraju svih analiza može se zaključiti kako je primjena ultrazvuka prilikom obrade soka utjecala na očuvanje nutritivne vrijednosti istog, te pogodovala očuvanju vrijednih bioaktivnih spojeva. Less

Abstract (english)

Heat treatment, compared with the other methods of food preservation, has an important advantage in ensuring food security and long-lasting storage due to its destructive effect on enzymes and microorganisms. However, the non-specific effect of heat can cause a decrease in the nutritional and sensory quality of the food and impair its functional properties. In order to avoid the undesirable effects of heat, non-invasive methods are being used in food processing, which primarily ensure... More the preservation of nutritional quality of the product. One of the mentioned techniques is also ultrasound, which is classified as a non-thermal method. High-intensity ultrasound (in the range of 10-1000 W/cm² and frequency of 20-100 kHz) is used in food technology, which, due to the action of the main cavitation mechanism, results in mechanical, physical and chemical changes. The aim of this study was to determine the influence of heat and ultrasonic treatment on the nutritional quality of strawberry juice. For the purpose of conventional heat treatment a pasteurization process was carried out at two treatment temperatures (60 °C and 80 °C) for 15 and 35 min, while ultrasonic treatment of the juice was performed in an ultrasonic bath (35 kHz and 40 W) at room temperature and at 60 °C and 80 °C for 15 and 35 min. From the nutritional parameters of strawberry juice, analysed were following: physicochemical properties (dry matter content, total soluble solids, total acids, pH value and electrical conductivity); content of bioactive compounds (vitamin C, total phenols, flavonoids, non-flavonoids, anthocyanins) and antioxidant capacity. Based on the obtained results, it was determined that ultrasound did not significantly affect most of the physicochemical properties of strawberry juice, except total acids content. Pasteurization has led to an increase in dry matter content and electrical conductivity. Regarding the content of the studied specialized metabolites, ultrasound influenced the increase in the content of vitamin C, total phenols, total anthocyanins and antioxidant capacity. Based on the obtained results, can be concluded that ultrasound application significantly affected on the preservation of nutritional value and also on the content of bioactive compounds in strawberry juice. Less

• Keywords: ultrazvuk; pasterizacija; sok od jagode; bioaktivni spojevi; antioksidacijski kapacitet
• Keywords (english): ultrasound; pasteurization; strawberry juice; bioactive compounds; antioxidant capacity
• Language: croatian
• URN:NBN: urn:nbn:hr:204:511544
• Study programme: Title: Horticulture; Study programme type: university; Study level: graduate; Academic / professional title: magistar/ magistra inženjer/inženjerka hortikulture (magistar/ magistra inženjer/inženjerka hortikulture)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-11-19 08:40:51