BIOACTIVE POTENTIAL OF FRUIT-BASED INFANT PURÉES: QUANTIFICATION OF TOTAL PHENOLIC COMPOUNDS VIA FAST BLUE BB ASSAY

The introduction of complementary foods at six months of age is crucial to meet infants' growing nutritional demands. Fruit and vegetable purées, whether homemade or commercially prepared, play a fundamental role in exposing children to new flavors, textures, and essential micronutrients during this critical developmental window. However, industrial processing methods such as thermal treatment and homogenization may compromise the stability and retention of heat-sensitive bioactive compounds. This study evaluated the total phenolic content in 15 commercial purées obtained from local retailers in Madrid, Spain, using the QUENCHER method, which enables direct analysis of lyophilized samples (400 mesh) without extraction or hydrolysis. The assay employed 0.1% (w/v) Fast Blue BB and 5% (w/v) NaOH, with gallic acid as standard. Data were analyzed by ANOVA and Tukey's test (p<0.05). Phenolic content varied significantly (0.26–24.74 mg GAE/100g). Sample P14 (three-fruit combination: pear, banana and apple) showed the highest value (24.74±0.34 mg GAE/100g), being 116% higher than the second richest sample (P10: apple and cereal, 11.46±0.29 mg GAE/100g). This marked difference suggests synergistic interactions between distinct phenolic profiles in mixed fruit matrices, where the combined antioxidant potential exceeds individual contributions. Purées containing red fruits (P15: apple and strawberry, 5.01±0.34 mg GAE/100g; P11: blueberry, banana and cereal, 5.00±0.02 mg GAE/100g) exhibited intermediate values. The relative thermal stability of anthocyanins likely preserved these antioxidant properties despite processing, though matrix effects from cereal incorporation may have modulated bioavailability. Notably, polyphenol diversity in multi-fruit formulations appears critical for optimizing phenolic retention, as evidenced by P14's exceptional performance compared to single-fruit alternatives. The QUENCHER–Fast Blue BB method proved effective for analyzing complex baby food matrices. Multi-fruit blends, especially with red fruits, can boost antioxidant intake and enhance infant nutrition.