Revisiting Spectrophotometric Methods in the FoodOmics Era: The Influence of Phytochemicals in the Quantification of Soluble Sugars in Plant-Based Beverages, Drinks, and Extracts

The rising prevalence of diet-related diseases is driving consumers to adopt healthier, plant-based diets. Aware of this consumer trend, the Food Industry is investing in innovative, tasty, plant-based foods with added nutraceutical value. However, health-promoting phytochemicals are often found in foods with a high content of natural sugars that are readily absorbed, undermining their health benefits. To ensure proper labelling and support consumers in their choices for healthier foods, the Food Industry relies on cost-effective methods to measure soluble sugars. Herein, we assess three established spectrophotometric assays-phenol, orcinol, and anthrone-for quantifying soluble sugars in 12 plant-based beverages, drinks, and extracts. The standard glucose solutions revealed that the phenol and orcinol reagents displayed the highest sensitivity. Applied to phytochemical-rich beverages, drinks, and extracts, the anthrone protocol leads to precipitation phenomena; the phenol is prone to interference from chlorophylls, carotenoids, melanoidins, (ellagi)tannins, and anthocyanins, whereas orcinol is susceptible only to anthocyanins. Though spectrophotometric assays overestimate sugar levels in both high- and low-sugar-content samples, the orcinol-sulfuric acid method offers an environmentally safe and cost-effective approach to quantifying soluble sugars in phytochemical-rich samples, fostering food innovation and helping to build consumer trust within resilient and sustainable food systems.