Purple rice (Oryza sativa L.) is a pigmented plant-based food whose starch is rich in the anthocyanins cyanidin-3-glucoside (C3G) and peonidin-3-glucoside (P3G), yet is largely rapidly digestible and confers a high glycemic index that limits its dietary use. Converting native starch into resistant starch type III (RS3) via dual autoclav-ing-retrogradation treatment (DART) or dual enzyme treatment (DET) lowers digesti-bility, but the conditions required compromise anthocyanin stability. This study tracked how these two food-processing routes govern phenolic and anthocyanin fate, structure and digestibility. RS3 content rose from 5.35% (native) to 34.13% (DART) and 51.34% (DET), while total phenolic content fell by 76.1% and 71.4% and the starch darkened (L* 68.27 to 43.49 and 28.25); free C3G became undetectable after DART but was partly retained (11.86 mg/100 g) after DET. X-ray diffraction showed A-type to B-type conversion after DART, whereas DET gave a mixed B+V-type pattern with a diagnostic peak near 2θ ≈ 19°, coinciding with greater phenolic retention. Both RS3 products resisted simulated digestion, with DET-RS3 limiting intestinal hydrolysis to 12.72% versus 30.71% for native starch. Processing thus entails a nutritional trade-off, partly offset in DET by amylose-phenolic complexation, positioning purple-rice RS3 as a candidate colon-targeted antioxidant delivery vehicle.

Clean-label strategies to lower the glycemic impact of starch-based foods are attracting growing interest, but supporting evidence remains fragmented across starch science, food engineering, digestion methodology, and clinical nutrition. This narrative review, informed by a structured literature search, integrates this evidence into a bottom–up framework linking raw material selection, physical processing, food matrix interactions, in vitro digestion, and human glycemic testing. Using pigmented rice as a model system, it examines how heat–moisture treatment, annealing, ultrasound, extrusion, microwave-assisted processing, and controlled retrogradation reorganize starch, and how hydrocolloids, proteins, lipids, and phenolic compounds reduce enzyme accessibility or enzyme activity. This review makes three contributions. First, mechanistic claims are graded as directly demonstrated, inferred from digestibility data, or hypothetical, and D-allulose–protein conjugation is explicitly treated as a hypothesis. Second, Englyst fractions, INFOGEST kinetics, hydrolysis index, estimated GI, and ISO 26642 human GI are compared as non-interchangeable outputs. Third, an implementation table specifies, for each tier, the design variable, analytical method, evidence required, and principal limitation. The framework is a decision support tool rather than a validated predictive model; formal low-GI claims require human testing, and applications such as 3D-printed foods for older adults require separate validation.