A Sustainable Inventory Model for Ameliorating-Deteriorating Items under Hybrid Demand and Trade Credit with Preservation Investment

This study develops an optimal inventory strategy for deteriorating products with the objective of maximizing total profit by jointly determining pricing, advertisement frequency, preservation investment, and replenishment policies under realistic market conditions. The proposed model incorporates time-varying amelioration and deterioration, with hybrid-type demand (dependent on both selling price and advertisement frequency). Preservation technology is included to reduce deterioration and improve product quality, while a trade credit policy enhances demand and retailer liquidity. Partial backlogged shortages are considered, with backordering depending on customers’ willingness to wait. To address parameter uncertainty, the model is formulated in both crisp and fuzzy environments using triangular fuzzy numbers, and the graded mean integration representation method is employed for defuzzification. Numerical examples are solved using Mathematica 13.0.1 to validate the model and highlight differences between crisp and fuzzy optimal solutions, supported by sensitivity analysis. The results demonstrate that preservation investment and trade credit significantly improve profitability, while fuzzy modeling provides more realistic decision support. The study offers valuable managerial insights for perishable and quality-sensitive industries.