Plant Sweetness, Taste, and Fragrance as an Energy-Balance Phenomenon: A Systems-Level Framework Integrating Absorption, Metabolic Allocation, and Loss Dynamics

Abstract

Plant sweetness, taste, and fragrance are critical determinants of sensory quality in fruits, flowers, and leaves, influencing ecological interactions, consumer preference, and crop value. These traits emerge from complex biochemical and physiological processes linking primary carbon assimilation with secondary metabolite biosynthesis and loss. While extensive molecular and biochemical research has elucidated individual pathways involved in sugar accumulation and volatile organic compound (VOC) synthesis, an integrative systems-level framework capable of explaining whole-plant sensory variation across environmental conditions remains limited.

This study proposes a phenomenological Plant Sweetness–Taste–Fragrance Energy Framework, grounded in mass balance, absorption–loss dynamics, and metabolic allocation theory. The framework conceptualizes sweetness, taste, and fragrance as emergent outcomes of absorbed resource supply, effective metabolic conversion capacity, secondary metabolite synthesis, and transpiration-driven loss. A set of linked equations is introduced to describe (i) resource absorption and biomass accumulation, (ii) effective biological mass and absorption–conversion capacity, (iii) a normalized fragrance energy index, and (iv) a refined rate expression integrating radiation input, stress modifiers, and compound-specific contributions.

Importantly, the framework explicitly distinguishes between physical energy (joules) and biological energy activity indices, avoiding thermodynamic inconsistency while preserving physiological interpretability. The proposed approach is consistent with established concepts such as net primary production, relative growth rate, and aroma retention efficiency, and aligns with extensive empirical evidence from horticultural and crop science. By integrating absorption, metabolic allocation, and loss processes into a single interpretive structure, this work provides a scientifically defensible and flexible tool for understanding why sweetness and fragrance intensify under optimal conditions and fade under stress.