Phenolic acids, flavonoids, vitamin C and antioxidant capacity of strawberry juices processed by high-intensity pulsed electric fields or heat treatments

Biological Activities and Effects of Food Processing on Flavonoids as Phenolic Antioxidants

“…Thermal pasteurization treatments (90°C, 60s) for strawberry juices have no effect on quercetin and kaempferol contents (Odriozola-Serrano et al, 2008), whereas it reduces naringin, rutin, quercetin and naringenin content for grapefruit juices (Igual et al, 2011). For Fuleki & Ricardo-Da-Silva (2003), pasteurization of grape juice increased the concentration of catechins in cold-pressed juices, but it decreased concentrations in hot-pressed juices.…”

Nutrient and polyphenolic composition of industrial strawberry press cake

“…Their beneficial influence is exerted by means of various complementary mechanisms that involve a number of bioactive compounds such as tannins, flavonoids, and phenolic acids [7]. Strawberries are known to be a rich source of polyphenols, such as ellagitannins (ETs) [8,9], proanthocyanidins [4,10,11], anthocyanins [4,12], and flavonols (mostly quercetin and kaempferol glycosides) [2,13]. Ellagitannins are thought to be the most important polyphenols in strawberries.…”

The Effects of Non-Thermal Technologies on Phytochemicals

“…Among them, flavones, flavonols, flavanols, flavanones, anthocyanins, and isoflavones are particularly common in fruits. In strawberry juices, p-hydroxybenzoic content was enhanced slightly but significantly after PEF processing (35 kV/cm for 1700 μs in bipolar 4-μs pulses at 100 Hz) compared to the untreated juice, whereas ellagic acid was substantially reduced when the heat treatment was conducted at 90ºC for 60 s. No significant differences in flavonol (kaempferol, quercetin and myricetin) content were obtained between fresh and treated strawberry juices; thus, these phenolic compounds were not affected by processing (Odriozola-Serrano et al, 2008c). It is well known that anthocyanins are unstable pigments and can be decolorized and degraded by many factors such as temperature, pH, oxygen, enzymes, light, the presence of copigments and metallic ions, ascorbic acid, sulphur dioxide and sugars.…”

“…The concentration of vitamin C in thermally and PEF-processed juices decreased gradually with storage time. Although during 21 days of storage the concentration of vitamin C was similar among processed strawberry juices, beyond this day, juices subjected to thermal treatment at 90 ºC for 60 s exhibited lower vitamin C content compared to PEF-treated juices (Odriozola et al, 2008c). Recommended daily intake (RDI) of vitamin C is currently revised but should be never below 60 mg, as established by the U.S. Food and Drug Administration (FDA, 1999).…”