Ah, the enigma of the burst in glucose release after 210 minutes in your in vitro starch digestibility experiment! Allow me to unravel this mystery for you. Firstly, consider the nature of basmati rice cultivars, which may exhibit variations in starch composition and structure, leading to differential digestion rates. Additionally, the protocol you're following, devised by Fitzgerald et al. in 2011, while reliable, might not perfectly capture the intricacies of your specific rice samples. It's plausible that certain inherent factors, such as variations in enzymatic activity, could contribute to this glucose burst. Environmental conditions during the experiment, like temperature or pH fluctuations, could also influence enzymatic kinetics and subsequently impact starch digestion. Furthermore, the presence of any undigested particles or aggregates in your sample might delay the release of glucose until they are eventually broken down after the 210-minute mark. Ultimately, this unexpected phenomenon showcases the intricate interplay between inherent starch properties, experimental techniques, and environmental factors, rendering your results an intriguing puzzle awaiting resolution.