Metabolomics profiling and antimicrobial activity of fermented date fruit (Khastawi) used as functional ingredients for making Asian confectionary (Dodol)

Figures & data

Table 1. Antifungal activity of fermented date fruit at different concentrations against the selected moulds.

Moulds	Growth inhibition (%) at different concentrations
	25 µL	50 µL	100 µL
Aspergillus niger	40.06 ± 0.58^c	52.03 ± 0.25^b	90.85 ± 0.22^a
Aspergillus flavus	51.93 ± 0.18^c	63.71 ± 0.31^b	92.86 ± 0.31^a

Mean values ± Standard deviation of triplicate readings.

Small letters represent significant differences within the column (p˂0.05).

Table 2. Antibacterial activity* of fermented date fruit extract at different concentrations.

	Pathogenic bacteria
Treatment	E. coli	S. aureus
Extract 25 µL	10.00 ± 0.80^c	12.00 ± 0.10^c
Extract 50 µL	11.00 ± 0.65^c	12.00 ± 0.35^c
Extract 100 µL	13.00 ± 0.40^b	15.00 ± 0.15^ab
Tetracycline (30 μg)	16.00 ± 0.14^a	17.00 ± 0.70^a
Ampicillin (10 μg)	10.00 ± 0.12^c	14.00 ± 0.22^bc

* The diameter for the clear zone was measured and expressed as (mm).

Mean values ± Standard deviation of triplicate readings.

Small letters represent significant differences within the column (p˂0.05).

Figure 1. Representative ¹H nuclear magnetic resonance (NMR) spectrum of fermented date fruit from 1 ppm to 6 ppm with the identified metabolites.

Table 3. The concentration (mmol mL⁻¹) of the major metabolites in fermented date fruit and their antimicrobial activity as determined by the ¹H-NMR analysis.

Compound	Chemical shifts ppm	Concentration (mmol mL^-1)
Propylene glycol	δ 1.13 (d)	0.028
Lactic acid	δ 1.32 (d), δ 4.1 (q)	0.763
Alanine	δ 1.46 (d)	0.013
Arginine	δ 1.61 (m)	0.075
4-Hydroxybutyrate	δ 1.76 (m)	0.026
Lysine	δ 1.89 (m)	0.051
Acetic acid	δ 1.96 (s)	0.292
Acetoin	δ 2.21 (s)	0.046
Dimethylamine	δ 2.52 (s)	0.024
N-Acetyl-L-tyrosine	δ 2.84 (dd)	0.078
gamma-Aminobutyric acid	δ 3.00 (t)	0.041
β-Alanine	δ 3.17 (t)	0.867
Proline	δ 3.33 (dt), δ 3.41 (dt)	0.452
Cystine	δ 3.38 (dd)	0.404
Xylose	δ 3.31 (dd), δ 3.42 (t), δ 4.57 (d), δ 5.19 (d)	1.054
Glucose	δ 3.524 (m), δ 3.728 (m), δ 3.824 (m)	1.724
Fructose	δ 3.577 (m), δ 3.695 (m), δ 4.005 (m)	1.940
Erythritol	δ 3.61 (m)	0.188
Arabinose	δ 3.95 (m), δ 4.02 (m)	0.751
Choline	δ 4.056 (ddd)	0.103

Figure 2. Growth of the A. niger and A. flavus and incubated on the surface of Dodol incubated at 25 ± 2 °C; (A) traditional Dodol day 1, (B) traditional Dodol day 7, (C) modified Dodol day 1, and (D) modified Dodol day 7.

Table 4. Spore and cell counts for the traditional and modified Dodol expressed as spore and or CFU g⁻¹.

Sample	A. flavus	A. niger	E. coli	S. aureus
Traditional Dododl	9.1 × 10^9	3.7 × 10^9	6.4 × 10^4	2.7 × 10^4
Modified Dodol	7.4 × 10^5	3.2 × 10^7	ND	ND

Not detected (ND).

Table 5. Physiochemical properties for the traditional and modified Dodol.

Parameters	Traditional Dodol	Modified Dodol
Moisture content (%)	21.50 ± 1.22^b	29.40 ± 2.74^a
Water activity (aw)	0.81 ± 0.02^b	0.84 ± 0.06^a
Firmness (g)	137.66 ± 9.80^a	97. 24 ± 3.48^b
Colour, L	59.95 ± 4.30^b	73.71 ± 7.90^a
a	6.42 ± 0.29^a	1.18 ± 0.42^b
b	18.27 ± 0.80^a	8.33 ± 1.15^b

Mean values ± Standard deviation of triplicate readings.

Small letters represent significant differences within the row (p˂0.05).

Table 6. Consumer preference evaluation for traditional dodol and modified Dodol.

Attributes	Traditional Dodol	Modified Dodol
Taste	6.55 ± 1.91^a	6.00 ± 1.77^a
Aroma	6.20 ± 2.00^a	6.00 ± 1.85^a
Colour	7.24 ± 1.53^a	7.38 ± 1.36^a
Appearance	7.14 ± 1.64^a	6.86 ± 1.46^a
Sourness	5.72 ± 2.95^a	5.59 ± 2.64^a
Texture	6.72 ± 1.73^a	6.10 ± 1.48^a
Sweetness	6.10 ± 2.42^a	6.14 ± 2.12^a
overall	6.53 ± 0.50^a	6.30 ± 0.45^a

Small letters show significant differences (p < 0.05) and same letters show no significant differences in the row.

Each value in the table is the mean ± SD of triplicates.

Data availability statement

The data supporting the findings reported in this study are available from the corresponding author upon reasonable request.