Low‐Temperature Blanching as a Tool to Modulate the Structure of Pectin in Blueberry Purees

Abstract

Blueberry composition was characterized for 6 cultivars. It contains a good amount of dietary fiber (10% to 20%) and pectin (4% to 7%) whose degree of methylation (DM) is sensitive to food processing. A low temperature blanching (LTB: 60 °C/1 h) was applied on blueberry purees to decrease pectin DM, in order to modulate puree properties and functionalities (that is, viscosity and stability), and to enhance pectin affinity toward other components within food matrices. Fiber content, viscosity, pectin solubility, DM, and monosaccharide composition were determined for both pasteurized, and LTB+pasteurized blueberry purees. The results showed that neither the amount of fiber, nor the viscosity were affected by LTB, indicating that this treatment did not result in any significant pectin depolymerization and degradation. LTB caused a decrease both in pectin DM from 58-67% to 45-47% and in the amount of water-soluble pectin fraction, the latter remaining the major fraction of total pectin at 52% to 57%. A LTB is a simple and mild process to produce blueberry purees with mostly soluble and low-methylated pectin in order to extend functionality and opportunities for interactions with other food ingredients.

Blueberry Pectin Extraction Methods Influence Physico‐Chemical Properties

“…() and Chevalier et al. (). DF.NSF and ADF.NSF had the lowest DE value of 11%, reflecting the impact of alkaline sodium carbonate and saponification of methoxyl groups of pectins.…”

“…The yield was determined gravimetrically. Based on dry weight, 31% of AIS was obtained from freeze‐dried blueberry powder, which was greater than the dietary fiber content, 22%, provided by the U.S. Highbush Blueberry Council and those of AIS obtained from six blueberry cultivars (Chevalier et al., ). Mild laboratory extraction may have co‐extracted pectin with different structures and other low molecular weight proteins or phenol; variance may also be attributed to different methods used.…”

“…The content of UA in DF.CSF and ADF.CSF were both 18 μg/mg AIS; UA content in DF.NSF and ADF.NSF was 18 and 21 μg/mg AIS, respectively. The yield of UA depends on cultivar and ranged from 4.7 to 7.4 g/100 g dry weight in frozen blueberries (Chevalier et al., ). In frozen blueberries, the yield of UA in WSF and CSF was 70 and 30 μg/mg AIS (Vicente et al., ) and 85 to 123 and 42 to 73 μg/mg AIS (Chevalier et al., ), respectively.…”

“…The yield of UA depends on cultivar and ranged from 4.7 to 7.4 g/100 g dry weight in frozen blueberries (Chevalier et al., ). In frozen blueberries, the yield of UA in WSF and CSF was 70 and 30 μg/mg AIS (Vicente et al., ) and 85 to 123 and 42 to 73 μg/mg AIS (Chevalier et al., ), respectively. In this study, the yield of UA from freeze dried blueberry powder derived from mixed Tifblue/Rubel cultivar was 17 to 21 μg/mg AIS which was two to six times lower than previously reported by (Chevalier et al., ; Vicente et al., ).…”

“…Three pectin‐rich fractions from mixed cultivar Highbush blueberry powder were extracted and the interaction with anthocyanins was measured (Lin, Fischer, & Wicker, ). Low temperature blanching at 60 °C, a desirable temperature to activate pectinmethylesterase, decreased the degree of esterification of pectins from blueberry purees (Chevalier, Rioux, Angers, & Turgeon, ).…”