Postharvest gas treatments for almonds: Efficacy, lipid oxidation and practical implications for quality preservation

Postharvest management of high-oil nuts such as almonds must reconcile disinfestation with preservation of lipid quality. Rigorous, life-stage–resolved comparisons that quantify both insect control and almond quality remain scarce. An integrated benchmark was conducted on shelled almonds infested with Tribolium castaneum (Herbst, 1797; Coleoptera: Tenebrionidae) and Oryzaephilus surinamensis (Linnaeus, 1758; Coleoptera: Silvanidae) (larvae and adults), evaluating three gaseous treatments: ozone (O 3 ; 500 ppm, 6 h), phosphine (PH 3 ; 1 g m −3 , 7 d), and an ECO 2 Fume CO 2 -based treatment (50 g m −3 , 3 d). Across five independent replicates, biological endpoints (mortality, fecundity, nutritional indices, energy conversion index, and almond weight loss) were quantified alongside a chemical quality panel (proteins, Thiobarbituric acid reactive substances, free fatty acids, proximate composition, minerals, total phenolics, oil). PH 3 achieved the highest and most consistent mortality (≈89–99%) and markedly suppressed feeding and progeny while inducing only minor immediate changes in lipid-oxidation indices. The CO 2 -based treatment delivered comparable control (≈86–94%) with modest chemical shifts and pronounced reductions in consumption and weight loss. By contrast, O 3 produced only moderate insecticidal effects (≈55–66% mortality) but caused clear oxidative deterioration (ΔPV = +2.31; ΔTBARS = +0.90; ΔFFA = +0.145; total phenolics ≈ −15.9%). Multivariate synthesis of Principal component analysis (PCA) and Canonical variate analysis (CVA) indicated that a primary axis dominated by oxidation markers explained ∼88% of treatment variance (Can1; P < 0.001), whereas a secondary axis captured insect-response variation (∼11%; Can2; P < 0.001). Findings delineate a practical trade-off between pest suppression and lipid-quality preservation and support prioritization of PH 3 or CO 2 -based approaches over ozone for high-oil commodities unless oxidative impacts can be mitigated. • PH 3 and CO 2 -based fumigation gave the highest mortality across stages. • Ozone delivered intermediate control but the largest lipid-oxidation shifts. • PH 3 /CO 2 sharply reduced kernel weight loss in larval-driven damage assays. • CVA showed oxidation markers dominate treatment separation (∼88% variance). • Proximate nutrients stayed stable; phenolics declined most under ozone.