Effects of Blanching on Flavanones and Microstructure of Citrus aurantium Peels

• Published in: Food and bioprocess technology Vol. 8; no. 11; pp. 2246 - 2255
• Main Authors: Ben Zid, Malek, Dhuique-Mayer, Claudie, Bellagha, Sihem, Sanier, Christine, Collignan, Antoine, Servent, Adrien, Dornier, Manuel
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.11.2015; Springer Nature B.V; Springer
• Subjects: Agriculture; Albedo; Biotechnology; Bitterness; Blanching; Cell walls; Chemical and Process Engineering; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Color; Darkening; Discoloration; Disintegration; Drying; Engineering Sciences; Food and Nutrition; Food Science; Fruits; Life Sciences; Light microscopy; Optical microscopy; Original Paper; Porosity; Steam; Steaming; Structural changes; Porosity; Citrus peels; Blanching; Flavanones glycosides
• ISSN: 1935-5130; 1935-5149
• DOI: 10.1007/s11947-015-1573-1

Water and steam blanching were investigated as pretreatments of bitter orange peels in order to modulate their bitterness before further formulation processing such as osmotic treatment and drying. The fruit pieces were water blanched at 95 °C for 10 min and at 85 °C for 60 min and steam blanched at atmospheric pressure during 5 min. The kinetics of water inflow and bitter flavanone losses were established from the variation of moisture and bitter compound contents during the blanching process. The whiteness and the citrus color indexes were adopted to evaluate respectively the color of the flavedo and the albedo. Thin sections of fresh and treated peels were resin embedded for light microscopy evaluation and optical porosity determination. Results revealed that water blanching could partially debitter the peels by removing about 38 and 48 % of bitter flavanones (naringin, neohesperidin, neoeriocitrin) respectively at 95 and 85 °C. The citrus color index and the whiteness index decreased during the process denoting a flavedo discoloring and an albedo darkening. By contrast, the steam blanching showed good retention of bitter compounds. The color of the flavedo was unaffected by steaming while the whiteness index decreased. At microscopic level, the water-blanched peels exhibited an extreme swelling of the cell walls and slight disintegration of the tissue. Contrariwise, the steam blanching maintained the structure of the peels and brought about the shrinkage of the albedo tissue and the decrease of porosity.