Table 4. Selected volatile compounds, odor descriptors, and peak areas detected by electronic nose in Protaetia brevitarsis larvae from the control (GRP) and formulated-diet (FD1-FD3) treatment groups after gut-evacuation pretreatment

Column	Compound¹⁾	Rt (min)²⁾	Odor descriptor³⁾	Peak area
Column	Compound¹⁾	Rt (min)²⁾	Odor descriptor³⁾	Control (GRP⁴⁾)	FD1	FD2	FD3
MTX-5	Butane-2,3-dione	19.1	Butter, caramelized, chlorine, creamy, fruity	1,298.1±76.7^5)a6)	732.0±26.7^b	872.0±73.8^b	293.4±199.4^c
	Butanal	22.3	Chocolate, cocoa, green, malty, musty	239,932.6±47,551.3^a	14,072.7±648.5^b	19,854.1±1428.8^b	17,802.7±435.2^b
	2,3-Pentanedione	32.9	Almond, apple, butter, burnt, butterscotch	4,445.7±1,032.3^a	ND⁷⁾	ND	ND
	Propyl propanoate	44.8	Apple, chemical, fruity, fruity (sweet), pineapple	1,175.6±116.5^c	1,770.1±219.2^b	3,310.5±194.6^a	1,542.7±207.1^bc
	2-Heptanone	52.0	Banana, cheese, coconut, fruity, gaseous	209.3±82.3^c	447.2±30.0^b	1,286.9±96.9^a	414.6±57.6^b
	Heptanal	52.9	Aldehydic, citrus, fatty, fish (dry), fresh	2,391.3±443.7^a	570.4±81.4^c	1,164.3±97.0^b	649.7±67.1^bc
MTX-1701	Anethole	83.1	Anise, herbaceous, licorice, oil, spicy	ND	ND	91.6±11.9^a	ND

Volatile compounds were tentatively identified by electronic-nose analysis based on retention time and the instrument library.
Rt, retention time.
Odor descriptors are library-based terms associated with the tentatively identified volatile compounds and do not represent sensory-panel data.
GRP, larvae provided with the control diet (glutinous rice powder) during the depuration step (control group); FD1-FD3, larvae provided with formulated diets 1-3 during the depuration step (formulated-diet groups).
All values are mean±SD (n=3).
Different superscript letters within the same row indicate significant differences among treatment groups at p<0.05 by one-way ANOVA followed by Tukey’s HSD test.
ND, not detected.