Effect of UV-C irradiation and high hydrostatic pressure on shelf-life and quality of minimally processed potatoes (Solanum tuberosum L.)

doctoral thesis

• Title (croatian): Utjecaj UV-C zračenja i visokoga hidrostatskoga tlaka na trajnost i kvalitetu minimalno procesiranoga krumpira (Solanum tuberosum L.)
• Author: Zdenka Pelaić
• Mentor: Branka Levaj (mentor)
• Committee member: Maja Repajić (predsjednik povjerenstva)
• Committee member: Kata Galić (član povjerenstva)
• Committee member: Zoran Zorić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Food Technology and Biotechnology; (Department of Food Engineering); (Laboratory for Technology of Fruits and Vegetables Preservation and Processing); Zagreb
• Defense date and country: 2023, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Food Technology
• Universal decimal classification (UDC): 633/635 - Horticulture. Fruit growing. Viticulture. Gardening

Abstract

The aim of this study was to examine the effects of different UV-C doses and high hydrostatic pressure (HHP) conditions on the safety and quality of minimally processed (fresh-cut) potatoes (FCP), and on the sensory properties of raw and thermally treated FCP, while observing the changes during storage. Based on the obtained results, the goal was to compare the effects of optimal UV-C and HHP treatment, as well as their combination, on the properties of FCP. In the first and second part of the research, FCP was treated with a 2% sodium ascorbate solution (SA) and vacuum packed (VP), treated with UV-C (0, 3, 5 and 10 min), and stored (23 days/6 °C). In the third part, FCP was treated with HHP (400 MPa/0, 3, 5 and 10 min) in vessels containing SA solution, VP and stored. In the fourth part, the samples were prepared as in the first part and treated: UV-C (5 min), HHP (400 MPa/3 min) and combined: UV-C (5 min)/HHP (400 MPa/3 min). 5- and 10-min UV-C treatments effectively slowed the growth of aerobic mesophilic bacteria during storage and positively affected the color and odor of raw FCP, while the thermally treated samples had a more pronounced odor and taste. The UV-C decreased the content of chlorogenic acid (CA) in raw FCP. A 5-min UV-C treatment increased the content of reducing sugars (RS) in raw and acrylamide in fried FCP, which was below the suggested limit. Thermal treatment reduced the content of CA and RS. The UV-C treated FCP maintained safety, quality and sensory properties for 15 days. Due to the similar antimicrobial effect of 5- and 10-min UV-C treatments and to save energy, 5-min UV-C was chosen for further investigations. 10-min HHP treatment significantly reduced the bacteria count. The 5- and 10-min treated samples had lower sensory scores, and showed texture damage during frying. The 3-min treatment resulted in significantly slower bacterial growth during storage and lower sensory scores for the boiled and fried FCP compared to control. For further tests, a 3-min HHP was chosen, but in VP without liquid. When comparing UV-C, HHP and UVC/HHP treatment, the greatest reduction of bacteria and their slowest growth during storage was observed in UV-C/HHP treated samples. The greatest decrease in CA was observed in HHP treated samples. All treatments increased the content of RS, significantly UV-C/HHP with a significant increase in acrylamide content of in fried FCP. The levels of PAHs were below the established limits. The acceptable sensory properties of the samples (raw, boiled and fried) remained stable during the 15-day storage period.

Abstract (croatian)

Cilj ovog istraživanja bio je ispitati učinak različitih UV-C doza i uvjeta visokoga hidrostatskoga tlaka (VHT) na sigurnost i kvalitetu minimalno procesiranoga krumpira (MPK), te na senzorska svojstva sirovoga i termički obrađenoga, uz praćenje promjena tijekom skladištenja. Nadalje cilj je bio na temelju dobivenih rezultata usporediti utjecaj optimalnoga UV-C i VHT tretmana, kao i njihove kombinacije na svojstva MPK-a. U prvom i drugom dijelu istraživanja MPK je tretiran s 2% otopinom natrijeva askorbata i vakuum pakiran (VP), tretiran UV-C-om (0, 3, 5 i 10 min), te skladišten (23 dana/6 °C). U trećem dijelu MPK su tretirani VHT-om (400 MPa/0, 3, 5 i 10 min) u posudama s otopinom NaAs, te VP i skladišteni. U četvrtom dijelu svi su uzorci pripremljeni kao u prvom i tretirani: UV-C (5 min), VHT (400 MPa/3 min) i kombinacijom UV-C (5 min)/VHT (400 MPa/3 min), te skladišteni. 5- i 10-min UV-C tretmani efikasno su usporili rast ukupnog broja aerobnih mezofilnih bakterija tijekom skladištenja, pozitivno utjecali na boju i miris sirovog SRK-a, dok su termički obrađeni su imali izraženiji miris i okus. Djelovanjem UV-C-a sadržaj klorogenske kiseline (KK) u sirovom MPK-u se smanjio. 5- min UV-C tretman je povećao sadržaj reducirajućih šećera (RS) u sirovom i sadržaj akrilamida u prženom MPK-u, ali je bio ispod predloženog limita. Termičkom obradom smanjio se sadržaj KK i RS. MPK tretiran UV-C-om zadržao je sigurnost, kvalitetu i senzorna svojstva 15 dana. Zbog sličnog antimikrobnoga učinka 5- i 10-min UV-C tretmana i radi uštede energije, 5-min UV-C odabran je za daljnje istraživanje. 10-min VHT tretman značajno je smanjio je broj bakterija. Uzorci tretirani VHT-om 5 i 10 min bili su senzorski slabije ocijenjeni, te su pokazali oštećenja teksture tijekom prženja. 3-min VHT tretman rezultirao je sporijim rastom bakterija tijekom skladištenja i lošijim senzorskim ocjenama kuhanog i prženog MPK-a u donosu na kontrolne uzorke. Za za daljnje ispitivanje odabran je 3-min VHT, ali u VP bez tekućine. Uspoređujući UV-C, VHT i kombinirani UVC/VHT tretman, najveće smanjenje broja bakterija i njihov najsporiji rast tijekom skladištenja uočen je u uzorcima tretiranim UV-C/VHT. Najveće smanjenje sadržaja KK zabilježeno u uzorcima tretiranim VHT-om. Svi tretmani povećali su sadržaj RS, a značajno UV-C/VHT uz značajno povećanje sadržaja akrilamida u prženom MPK-u. Razine PAH-ova su bile ispod utvrđenih granica. Prihvatljiva senzorska svojstva uzoraka (sirovih, kuhanih i prženih) ostala su stabilna tijekom 15 dana skladištenja.

• Keywords: fresh-cut; UV-C; HHP; browning; aerobic bacteria; chlorogenic acid; reducing sugars; acrylamide; PAHs; sensory properties
• Keywords (english): svježe rezani; UV-C; VHT; posmeđivanje; aerobne mezofilne bakterije; klorogenska kiselina; reducirajući šećeri; akrilamid; PAH-ovi; senzorska svojstva
• Language: english
• URN:NBN: urn:nbn:hr:159:279889
• Promotion: 2023
• Study programme: Title: Postgraduate PhD Study in Nutrition; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/ doktorica znanosti, područje biotehničkih znanosti, odgovarajuće polje (određeno matičnom strukom) (doktor/ doktorica znanosti, područje biotehničkih znanosti, odgovarajuće polje (određeno matičnom strukom))
• Type of resource: Text
• Extent: 195 str. ; 30 cm
• File origin: Born digital
• Access conditions: Open access
• Created on: 2023-11-14 11:11:05