Optimization of the conditions of alkaline extraction of tomato peels and characterization of tomato peel extracts obtained under atmospheric and oxygen free conditions

KOÇAK, ERİNÇ; ESMER, OZLEM K.; SAHINER, ASLI

doi:10.1590/0001-3765202320220077

Acessibilidade / Reportar erro

Brasil

Anais da Academia Brasileira de Ciências

Español English

Brasil

Español English

sumário « anterior atual seguinte »

Sumário

ENGINEERING SCIENCES • An. Acad. Bras. Ciênc. 95 (suppl 1) • 2023 • https://doi.org/10.1590/0001-3765202320220077 copy

Optimization of the conditions of alkaline extraction of tomato peels and characterization of tomato peel extracts obtained under atmospheric and oxygen free conditions

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

This study aims to optimize the extraction conditions to obtain the highest yield, to characterize tomato peel extract (TPE) under optimized conditions, and also to determine the effect of ambient oxygen on the properties of TPE. Optimisation were performed at three temperatures (60 °C, 80 °C, 100 °C) and three periods (2, 4, 6 h) by the response surface methodology. The properties of the extract under atmospheric and oxygen-free conditions (AC, OFC) were analysed to determine whether the characteristics of both extracts changed depending on the presence of oxygen; moreover, the morphological, chemical, thermal, biochemical, and antimicrobial properties were analysed. The maximum yield was 31.3% at 100 °C/6 h. A quadratic model was used to create the best fit. Both TPE samples exhibited similar morphological structure, similar weight losses at three stages of TGA curve, similar band assignments in FTIR spectra. GC-MS analysis showed that both samples mainly consisted of cutin in abundance of 70.45% and 68.14% for AC and OFC, respectively. OFC had higher total phenolic content possibly depending on the absence of oxygen. AC and OFC extracts exhibited substantial antimicrobial activity against S. aureus, E. coli, C. albicans, and A. brasiliensis with a MIC value of 100 μg TPE/ mL.

Key words
Alkaline extraction; characterization; optimization; response surface methodology; tomato industry wastes; tomato peels

Run	Temperature (C)	Time (h)	Extraction yield (g/100 g dry peel)
1	60.00	2.00	10.20
2	60.00	4.00	11.85
3	80.00	2.00	13.30
4	80.00	6.00	23.45
5	100.00	4.00	24.85
6	80.00	4.00	16.00
7	100.00	6.00	32.04
8	100.00	6.00	30.58
9	100.00	2.00	20.45
10	100.00	2.00	20.50
11	80.00	2.00	16.20
12	60.00	6.00	17.94
13	60.00	6.00	16.26
14	80.00	4.00	19.00
15	60.00	4.00	12.65
16	60.00	2.00	13.30
17	100.00	4.00	25.90
18	80.00	4.00	17.15
19	80.00	6.00	22.20

Source of variation	Sum of Squares	Degree of Freedom	Mean of Squares	F	p
Model^c	663.15	5	132.63	88.16	< 0.0001^a
A-temperature	433.44	1	433.44	288.11	< 0.0001
B-time	196.18	1	196.18	130.40	< 0.0001
AB	15.04	1	15.04	10.00	0.0075
A²	8.51	1	8.51	5.66	0.0334
B²	8.21	1	8.21	5.46	0.0362
Residue	19.56	13	1.50
Lack of Fit	1.84	3	0.61	0.35	0.7934^b
Pure Error	17.72	10	1.77
Overall	682.71	18

Peaks	FTIR / cm^-1		Assignment^b
Peaks	AC	OFC	Assignment^b
1	3343	3326	str O-H---O
2	2924	2924	str asymmetric CH₂
3	2851	2850	str symmetric CH₂
4	1701	1698	str C=O free acid group
5	1629	1643	str C=C double bonds of phenolic acids
6	1605	1604	str C-C aromatic
7	1558	-	str C-C aromatic conjugated with C=C
8	1515	1515	str C-C aromatic conjugated with C=C
9	1466	1464	str. C-C aromatic in phenolic compounds
10	1463	-	bend CH₂
11	1436	1436	str C-C aromatic in phenolic compounds
12	1410	1410	bend (O-H) carboxylic acid
13	1343	1364	NA^e
14	1331	1336	ring vibration of pectin^c
15	1309	1314	wagging CH₂ ^f
16	-	1279	(C-O) streching asymmetric carboxylic acid
17	1253	1250	bend (O-H) of primary and secondary of possible polysaccharides
18	1243	1229	str (C-O) of pectin^c
19	1217	1223	str (C-C) chain
20	1203	1203	NA^e
21	1168	1169	str. asymmetric and symmetric C-O-C ester
22	1105	1119	str. asymmetric and symmetric C-O-C ester
23	1045	1057	bend of (O-H) primary and secondary or str. (C-O) in polysaccarides
24	1033	1029	str. (C-O); (C-C) pectin^d
25	950	929	bend (O-H) carboxylic acid
26	902	898	bend C1-H β anomeric link of cellulose, xyloglucane^f,g
27	852	-	Out of plane bending (C-O) and (C-C) aromatic
28	835	834	Out of plane bending (C-O) and (C-C) aromatic
29	-	721	bend CH₂

Academia Brasileira de Ciências Rua Anfilófio de Carvalho, 29, 3º andar, 20030-060 Rio de Janeiro RJ Brasil, Tel: +55 21 3907-8100 - Rio de Janeiro - RJ - Brazil
E-mail: aabc@abc.org.br

Acompanhe os números deste periódico no seu leitor de RSS

[1] Correspondence to: Erinç Koçak E-mail: erinckocak@gmail.com