2.1.2.2.1 Severity of disease

Data presented in Table 1 show the rot fugal disease severity of JA tubers exposed to caraway oil and infected with fungal pathogen S. rolfsii under the two storage methods. The disease severity increased with the increasing the storage period over to the storage methods. JA tubers infected with S. rolfsii and exposed to emulsion of caraway essential oil (O + P) in peat moss layer at 25°C significantly reduced the disease severity compared to the cold storage method after 4 months storage. Infected-control JA tubers (P) and storage in peat moss layer at 25°C significantly reduced the disease severity for 2 months of storage compared with cold storage method, after which, the tubers were fully decadent. On the other hand, control-uninfected JA tubers (C) and storage in peat moss layer at 25°C significantly reduced the disease severity (caused by reasons other than S. rolfsii) compared with the storage under cold storage method. Caraway essential oil had the antimicrobial effects due to its content of basic constituents of monoterpenes, carvone and limonene. The basic constituents had a permeability effect on fungal

#### Figure 1.

Inhibition in mycelial dry weight of S. rolfsii as a function of the tested oils. Columns superscripted with the same letter are not significantly different at P ≤ 0.05 (Duncan test).


\* 1 = storage JA tubers in polyethylene bags at 4°C and 2 = storage JA tubers in peat moss layer at 25°C.

\*\*C = untreated control, P = infected tubers with pathogen, O = treated JA tubers with caraway essential oil and O + P = infected tubers with pathogen and treated with caraway essential oil. NA = not applicable due to full decay.

\*\*\*Means in each column followed by the same letter(s) were not significant at P= 0.05; where, (a) refer to the highest mean values, and (e) refer to the lowest mean values according to Duncan multiple range test.

Tubers rot in the untreated control (C) treatment was due to many reasons rather than the fungal pathogens.

#### Table 1.

Mean rot severity (%) of JA tubers treated with caraway essential oil and infected with S. rolfsii using two storage methods.

cell membrane, inactivation of some organic compounds and enzymes and/or the inhibition of conidial germination, eventually, the death of fungal pathogen [13]. Moreover, the use of essential oils in storage of JA may have many benefits, including, they are natural-ecofriendly products, biodegradable and multifunctional purposes.

Moreover, the activity of essential oils against may tend to reduce pathogenic fungi resistance reinforcement against chemical fungicide because they contain two or more stereo-isomers that may be located on multi-sites on the pathogen's plasma membrane. One of the valuable applications for peat moss is the traditional use in food preservation [14]. The antifungal effect of the use of peat mosses has been reported by many investigators against Aspergillus niger, A. flavus, Candida albicans, Cryptococcus albidus and Trichophyton rubrum [15]. The antifungal effect of peat moss may be related to some of its contains of extranutritional constituents or bioactive components like a pectin-like polymer and sphagnan, that inhibit fungal mycelium growth via electrostatic immobilization of extracellular enzymes and/or nitrogen deprivation, phenolics that inhibit the activity of extracellular enzymes of microbes or other constituents like sterols and polyacetylenes [16].

#### 2.1.2.2.2 Sprouting, weight loss and dry matter percentages of JA tubers

Table 2 show the mean data of weight loss and dry matter percentages of JA tubers exposed to emulsion of caraway essential oil and infected with fungal pathogenic S. rolfsii under using the two different storage methods. Results indicated that, the treatment of healthy JA tubers with emulsion of caraway essential oil completely inhibited the tubers sprouting and weight loss, but recorded the highest dry mater weight percentage along the storage period compared with the untreateduninfected control treatment over the use of the two different methods. Even after 120 days of storage period, the treatment of the use of JA tubers with caraway oil and infected with pathogenic fungi significantly decreased sprouting and weight loss percentages and increased dry matter content for JA tubers that stored in peat moss layers at 25°C than those stored in polyethylene bags at 4°C when compared

with the control (infected-untreated) tubers. On the other hand, storage of the untreated-uninfected JA tubers in peat moss layers at 25°C increased the sprouting, and dry matter content and decreased the weight of the tubers compared to the storage of tubers in polyethylene bags at 4°C. The bioactive components like limonene and carvone, in caraway essential oil are known to inhabit sprouting percentage of JA tubers by the suppressing of mitochondrial respiration and reducing carbohydrate deterioration sugar content. Carvone had a specific tool for inhibition of sprout growth of potato tubers, such as the repression of key enzyme in the mevalonate acid pathway, which is the main precursor of gibberellin biosynthesis [17]. On the other hand, peat moss has a relatively high water retention capacity; their cells can hold 16–25 times their dry weight of water [14]. This in turns

Mean sprouting, weight loss and dry matter weight (% 2SD) of JA tubers treated with caraway essential oil

1 = storage JA tubers in polyethylene bags at 4°C and 2 = storage JA tubers in peat moss layer at 25°C. \*\*C = untreated control, P = infected tubers with pathogen, O = treated JA tubers with caraway essential oil and

O + P = infected tubers with pathogen and treated with caraway essential oil.

\*\*\*NA = not applicable due to full decay.

and infected with S. rolfsii using two storage methods.

Criterion Storage

Dry matter weight

\*

Table 2.

103

method\*

DOI: http://dx.doi.org/10.5772/intechopen.87213

Treatment\*\* Storage period (day)

2 C 50.0 10.0 80.0 14.0 95.0 6.0 98.0 2.0

2 C 7.1 0.2 21.7 3.3 50.9 5.8 70.9 8.2

1 C 17.2 0.5 18.0 0.7 19.2 1.5 NA

2 C 22.6 0.4 23.0 0.3 21.0 0.5 21.5 1.1

Sprouting 1 C 40.0 10.0 70.0 4.0 90.0 4.0 NA

Effect of Essential Oils on Storability and Preservation of Some Vegetable Crops

Weight loss 1 C 20.5 2.9 35.7 5.3 59.9 8.0 NA

30 60 90 120

P NA\*\*\* NA NA NA O 0.0 0.0 0.0 0.0 O + P 3.8 0.1 3.9 0.1 4.0 0.4 4.3 0.2

P 3.6 0.4 4.8 0.4 NA NA O 0.0 0.0 0.0 0.0 O + P 0.0 0.0 0.0 0.0

P NA NA NA NA O 0.0 0.0 0.0 0.0 O + P 2.9 0.2 3.0 0.2 3.8 0.6 4.6 0.5

P 30.7 4.0 39.5 9.9 NA NA O 0.0 0.0 0.0 0.0 O + P 0.0 1.0 0.1 1.0 0.2 1.7 0.4

P NA NA NA NA O 22.5 0.4 22.9 0.6 23.6 0.3 24.9 0.6 O + P 22.0 0.2 22.3 0.4 23.3 0.9 23.5 0.8

P 18.6 0.6 17.0 0.5 NA NA O 23.6 0.5 24.6 0.8 24.9 0.5 25.8 0.5 O + P 23.5 0.4 23.7 0.6 24.2 0.4 25.5 0.3


Effect of Essential Oils on Storability and Preservation of Some Vegetable Crops DOI: http://dx.doi.org/10.5772/intechopen.87213

\* 1 = storage JA tubers in polyethylene bags at 4°C and 2 = storage JA tubers in peat moss layer at 25°C. \*\*C = untreated control, P = infected tubers with pathogen, O = treated JA tubers with caraway essential oil and

O + P = infected tubers with pathogen and treated with caraway essential oil.

\*\*\*NA = not applicable due to full decay.

#### Table 2.

cell membrane, inactivation of some organic compounds and enzymes and/or the inhibition of conidial germination, eventually, the death of fungal pathogen [13]. Moreover, the use of essential oils in storage of JA may have many benefits, including, they are natural-ecofriendly products, biodegradable and multifunctional

Mean rot severity (%) of JA tubers treated with caraway essential oil and infected with S. rolfsii using two

Storage method\* Treatment\*\* Storage period (day)

1 = storage JA tubers in polyethylene bags at 4°C and 2 = storage JA tubers in peat moss layer at 25°C.

Tubers rot in the untreated control (C) treatment was due to many reasons rather than the fungal pathogens.

tubers with pathogen and treated with caraway essential oil. NA = not applicable due to full decay.

values, and (e) refer to the lowest mean values according to Duncan multiple range test.

1 C 28.5b,\*\*\* 73.3<sup>a</sup> 100.0<sup>a</sup> NA

2 C 20.1<sup>c</sup> 33.6<sup>c</sup> 40.0<sup>b</sup> 66.5<sup>a</sup>

\*\*C = untreated control, P = infected tubers with pathogen, O = treated JA tubers with caraway essential oil and O + P = infected

\*\*\*Means in each column followed by the same letter(s) were not significant at P= 0.05; where, (a) refer to the highest mean

30 60 90 120

P 100.0<sup>a</sup> NA NA NA O 0.0e 0.0<sup>e</sup> 0.0<sup>d</sup> 0.0d O + P 8.9<sup>d</sup> 24.4<sup>d</sup> 37.5<sup>b</sup> 53.6<sup>b</sup>

P 20.0<sup>c</sup> 47.2b 100.0<sup>a</sup> NA O 0.0e 0.0<sup>e</sup> 0.0<sup>d</sup> 0.0d O + P 0.0e 0.0<sup>e</sup> 8.9c 13.3<sup>c</sup>

Moreover, the activity of essential oils against may tend to reduce pathogenic fungi resistance reinforcement against chemical fungicide because they contain two or more stereo-isomers that may be located on multi-sites on the pathogen's plasma membrane. One of the valuable applications for peat moss is the traditional use in food preservation [14]. The antifungal effect of the use of peat mosses has been reported by many investigators against Aspergillus niger, A. flavus, Candida albicans, Cryptococcus albidus and Trichophyton rubrum [15]. The antifungal effect of peat moss may be related to some of its contains of extranutritional constituents or bioactive components like a pectin-like polymer and sphagnan, that inhibit fungal mycelium growth via electrostatic immobilization of extracellular enzymes and/or nitrogen deprivation, phenolics that inhibit the activity of extracellular enzymes of

Table 2 show the mean data of weight loss and dry matter percentages of JA tubers exposed to emulsion of caraway essential oil and infected with fungal pathogenic S. rolfsii under using the two different storage methods. Results indicated that, the treatment of healthy JA tubers with emulsion of caraway essential oil completely inhibited the tubers sprouting and weight loss, but recorded the highest dry mater weight percentage along the storage period compared with the untreateduninfected control treatment over the use of the two different methods. Even after 120 days of storage period, the treatment of the use of JA tubers with caraway oil and infected with pathogenic fungi significantly decreased sprouting and weight loss percentages and increased dry matter content for JA tubers that stored in peat moss layers at 25°C than those stored in polyethylene bags at 4°C when compared

microbes or other constituents like sterols and polyacetylenes [16].

2.1.2.2.2 Sprouting, weight loss and dry matter percentages of JA tubers

purposes.

102

Table 1.

storage methods.

Essential Oils - Oils of Nature

\*

Mean sprouting, weight loss and dry matter weight (% 2SD) of JA tubers treated with caraway essential oil and infected with S. rolfsii using two storage methods.

with the control (infected-untreated) tubers. On the other hand, storage of the untreated-uninfected JA tubers in peat moss layers at 25°C increased the sprouting, and dry matter content and decreased the weight of the tubers compared to the storage of tubers in polyethylene bags at 4°C. The bioactive components like limonene and carvone, in caraway essential oil are known to inhabit sprouting percentage of JA tubers by the suppressing of mitochondrial respiration and reducing carbohydrate deterioration sugar content. Carvone had a specific tool for inhibition of sprout growth of potato tubers, such as the repression of key enzyme in the mevalonate acid pathway, which is the main precursor of gibberellin biosynthesis [17]. On the other hand, peat moss has a relatively high water retention capacity; their cells can hold 16–25 times their dry weight of water [14]. This in turns
