KR101373181B1 - A method of enhancing skin color and repressing flesh softening for postharvest persimmon fruits - Google Patents

Abstract

The present invention proposes a method for enhancing the skin pigmentation and softening during storage of the harvested persimmon fruit, when 1-MCP is treated immediately after harvesting and floating in persimmon persimmon fruit, the content of carotenoid pigment in the persimmon peel increases. At the same time the coloring is enhanced, there is an excellent effect of achieving the softening inhibitory effect of the flesh.

Description

A method of enhancing skin color and repressing flesh softening for postharvest persimmon fruits}

The present invention relates to a method for preventing hyperpigmentation and softening of pulp, which is involved in the appearance quality and functionality of sweet persimmon fruit.

Ultraviolet rays can cause disturbances such as necrosis and browning of plant tissues. UV C, particularly at wavelengths shorter than 280 nm, directly damages DNA molecules, causing cell death (Danon and Gallois, 1998). However, in general, hazards at low levels, which are not fatal, may act as stimuli that do not cause damage to plants but rather activate the response to stress, a phenomenon known as hormesis (Shama). And Alderson, 2005). For example, irradiation of low-dose ultraviolet rays to grapes during growth increases the synthesis of stilbene compounds, represented by resveratrol, which has strong antioxidant activity in response to photo-oxidative stress triggered by ultraviolet rays on leaves and fruits (Lancake and Pryce). , 1977). This UV hormesis can be used to reduce pests or improve quality after harvesting of horticultural products. Low dose UV radiation on plants can lead to changes in the production of various types of secondary metabolites, such as phenolic compounds, polyamines, and isoprenoids, which may have antimicrobial activity or affect the quality of horticultural products. Substances present (Jansen et al., 2008). The above-mentioned stilbene compound is a typical case, and the polyphenol-based stilbene contained in grapes is not only a powerful antiphylactic substance (phytoalexin) but also an important health functional ingredient that affects the functional quality of grapes or grape processed products (wine). Morales et al., 2000).

However, the pigment included in the persimmon fruit is an isoprenoid-based carotenoid, which includes carotene, lycopene, cryptoxanthin, lutein, and zeaxanthin (Wright and Kader, 1997). These carotenoid pigments not only affect the appearance quality by giving a specific fruit skin color to sweet persimmon fruit (Kays. 1999), but also have an antioxidant activity, and β-carotene is an important component of vitamin A in the human body. (Burri, 1997).

However, unlike polyphenolic compounds, the effect of UV irradiation on the synthesis of carotenoid pigments that do not strongly absorb UV light is reported to be different depending on the type of crop or tissue or the state of development (Jansen et al., 2008). There have been few reports of the effects of UV irradiation on carotenoid production in fruit, especially in the case of sweet persimmons. On the other hand, persimmon fruit belongs to climacteric type, although its production is insignificant compared to other kinds of fruit, the production and action of ethylene are closely related to the softening of the flesh and the softening of the fruit is the quality after harvesting from the persimmon fruit. One of the main causes of deterioration (Choi, 2010). Ethylene is not only produced with the maturation of fruit, but is well known to increase its production when the fruit is stressed (Abeles et al., 1992).

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a method for enhancing skin pigmentation and preventing flesh softening, which is devised in view of the above points, and which is involved in the quality and function of sweet persimmon fruit.

The above object of the present invention is to irradiate the persimmon fruit after harvest with ultraviolet rays to investigate the change in the production of carotenoid pigment as a factor affecting the appearance and functional quality of the fruit and also to cope with the increase in the production of stress ethylene due to the ultraviolet irradiation. After treatment with 1-methylcyclopropene (1-MCP), which is an ethylene inhibitor, it was achieved by investigating and evaluating the effects of UV irradiation.

Hereinafter, the specific contents of the present invention will be described in detail through examples and experiments.

In the present invention, by irradiating ultraviolet rays in parallel with the 1-MCP treatment for the sweet persimmon after harvesting, it is possible to obtain an excellent effect on the enhancement of hyperpigmentation and prevention of flesh softening.

1 is a hyperpigmentation comparison photograph of the ultraviolet treatment (bottom) and the untreated control (top) of the fruit of the present invention. Photographs were taken on day 10 after UV irradiation for 2 minutes after harvest.
Figure 2 is a chromatogram analysis of the carotenoid pigment of the skin in ESI positive ionization mode using HPLC-ESI-mass spectrophotometer. Lycopene / β-carotene and β-cryptoxanthin were detected at [M + H] ⁺ = 536.5 and 552.5.
Figure 3 is a graph showing the change in carotenoid pigment content after 1-MCP and UV treatment alone or in parallel to persimmon fruit after harvesting.
4 is a graph showing the effect of 1-MCP or ultraviolet treatment alone or in parallel treatment on the ethylene production and respiration of persimmon fruit according to the present invention.
5 is a graph showing the effect of 1-MCP or UV alone or in parallel treatment on the hardness of sweet persimmon fruit according to the present invention.

Experimental Materials and Processing

Sweet persimmon fruit harvested in early November at a farmhouse in Changwon, Gyeongnam ( Diospyros) kaki , var. Fuyu) was selected for fruit of uniform weight (180-200g) and fruit color and then transported to the laboratory on harvest day for experimental treatment. Treatment of 1-MCP was done immediately after laboratory transport and UV treatment was performed the next day after 1-CMP treatment was completed. The fruit was put into a 77L acrylic container of 15 kg each, and 6.2 mL of 1% (v / v) 1-MCP gas was injected, and the mixture was left to stand at room temperature for 16 hours to treat 1-MCP (processing concentration of about 1 ppm). .

In the ultraviolet treatment, an ultraviolet irradiator designed to transfer fruit by a conveyor belt to the center of a tunnel equipped with a germicidal UV lamp (G30T08 30 W, Sankyo Denki, Japan) was used. The UV lamp was spaced 15 cm from the fruit and arranged in six radial directions. The UV irradiation time was set so that the fruit was exposed to ultraviolet light for 2 minutes by adjusting the conveying speed of the conveyor belt. Treated or untreated fruits were packed in a large plastic bag of 0.04mm thickness and packed in a fruit box so as not to dry, and then stored at room temperature (18-20 ° C.) for 3 weeks. Five fruits were taken for each treatment at intervals of 3-4 days during storage, and the samples were analyzed at five repetitions per treatment with one fruit.

Measurement of pulp hardness

Rheometer (EZ test, Shimadzu, Japan) was used to measure the hardness of the pulp. When the 5mm diameter probe penetrated to the depth of 7mm into the flesh of the equator plane peeled to 2mm thickness, the maximum drag (N) applied to the probe was taken as the hardness of the flesh and the hardness was measured for each of two fruits of the equator plane.

Determination of Ethylene Production and Respiration

The fruit was sealed in a 500 mL container for 1 hour, and then an air sample in a 1 mL container was taken and injected into GC (GC-2010, Schmadzu, Japan) to analyze ethylene and CO ₂ concentrations. Ethylene analysis activated alumina column (80mesh, 3.2mm x 1m SUS, 110 ℃, carrier gas = 30mL min -1 N 2) was used and the FID (150 ℃), CO ₂ analysis active carbon column (80mesh, 3.2mm x 1m year, 110 ℃, carrier gas = He 30mL min ^-1 ) and TCD (150 ℃) was used.

Carotenoid   Preparation and Extraction of Pigment Assay Samples

The peeled peel was peeled to 2 mm thickness using an fruit peeler (Apple peeler, Kali, France) and then ground using a coffee grinder. The freeze-pulverized sample was dried using a freeze dryer (Vision, Korea) and stored at -70 ° C until the dye extractant was used. To extract the carotenoid pigment, add 50 mg of dry powder sample to a 10 mL centrifuge tube and add 5 mL of hexane / ethanol / acetone (50:25:25, v / v / v) for 5 minutes at 200 rpm in an orbital shaker. Stirred. Subsequently, 1 mL of distilled water was added thereto, mixed, and centrifuged to recover a supernatant containing a pigment. 2 mL of hexane / ethanol / acetone was further added to the lower aqueous solution, mixed, and centrifuged to extract the dye. The recovered supernatant was vacuum dried using Speed Vac (Vision, Korea). The dried samples were dissolved in 1 mL dichloromethane and stored at -70 ° C to be used for the analysis of carotenoid pigments.

Carotenoid  Analysis of the Pigment

After diluting the carotenoid assay sample dissolved in dichloromethane 10-fold in acetonotrile, 2 μL of the diluted sample was injected into HPLC (Waters Model 2696, USA). The column used for separation in HPLC was XTerra MS C18 (3.5μ, 150 x 2.1mm, Waters, USA), and isocratic conditions using acetonitrile / methanol (95: 5, v / v) at 0.25 mL min ^-1 flow rate. Sample components were separated at. Isolated lycopene, β-carotene, and β-cryptoxanthin were detected by single ion reaction (SIR) mode using a mass spectrometer (Waters Model 3100, USA). Mass sperctrometer was set under the following conditions; desolvation gas (N ₂ ) flow = 500L h ^-1 , cone gas (N ₂ ) flow = 50L h ^-1 , desolvation temp. = 400 ° C., source temp. = 120 ° C, capillary voltage = 4KV, ionization mode = electrospray (ES) positive, cone voltage = 30V.

According to the present invention, the experimental results by the experimental material and the test method are as follows.

<Ultraviolet rays investigation Cortical  Change>

When irradiated with ultraviolet persimmon fruit floating, the fruit skin color was darker red than the untreated fruit after several days (Fig. 1), and no disturbance symptoms due to ultraviolet irradiation were observed for 2 minutes. However, in the fruit exposed to ultraviolet rays for a long time over 5 minutes, black spots began to develop on the skin after 3-4 days, and the spot formation site enlarged with time. The UV lamp used in this experiment is a lamp that emits UV rays at 254 nm. UV C is known to induce cell death by damaging DNA molecules to an unrecoverable level when over-exposed to plants (Danon and Gallois, 1998). However, according to the principle of hormesis proposed by Lucky (1980), exposure to low doses of UV light causes repairable levels of DNA damage that can be repaired again. It acts as a stimulus to activate repair mechanisms, thereby enhancing the intracellular vital processes as part of homeostasis. In the case of persimmons, UV C irradiation within 2 minutes was not lethal to cells, but rather induced UV hormesis to promote carotenoid pigment synthesis, resulting in reorganization of intracellular accumulation.

< LC - MS Using carotenoid  Analysis of Pigments>

When carotenoids were analyzed using an HPLC-ESI-mass spectrometer, the same molecular weights of lycopene and carotene were detected in the SIR channel of m / z 536.5 and cryptoxanthin in the SIR channel of m / z 552.5 (Fig. 2). Persimmon contains β-carotene and β-cryptoxanthin (Wright and Kader, 1997). lycopene (Barba et al., 2006) has been reported, but when analyzed by LC-MS, in addition to those in floating persimmon fruit, a-carotene (m / z 552.5), lutein (m / z 568.5), zeaxanthin (m / z 568.5) and the like could be found further.

<Changes in Pigment Content According to Ultraviolet Irradiation>

In the floating persimmon fruit, the carotenoid pigment was mainly composed of β-carotene, lycopene, and β-cryptoxanthin (FIG. 3). The composition ratio of these pigments was different depending on the days after harvesting. At the time of harvest, β-carotene and β-cryptoxanthin were the major pigment components, and the lycopene content was as low as 1/10 of β-carotene. Lycopene, unlike other carotenoid pigments, is not found in photosynthetic tissue and is known to be found primarily in fruit (Bramley, 2000). In persimmon, lycopene is thought to accumulate only after harvest. In other words, the lycopene content began to increase rapidly with the progress of coloring after harvesting, and increased to 6.1 and 14.1 times after harvesting at 2 and 3 weeks after harvesting. In contrast, β-carotene contents increased 1.5 and 1.6 times after 2 and 3 weeks of harvest, respectively. On the other hand, β-cryptoxanthin increased by 2.3 times compared to the harvest time after one week after harvest, and did not show any significant change thereafter. Therefore, the skin color of suspended persimmons is mainly expressed by β-carotene, including some β-cryptoxanthin at or before harvest, but after harvesting, the accumulation of these pigments as well as the lycopene pigments significantly affects the expression of the skin color. I could think of it as On the other hand, UV irradiation resulted in an increase in β-carotene and lycopene content, especially in the increase of lycopene content. That is, after 2 weeks of UV irradiation, β-carotene content was increased by 1.2 times compared with no treatment, while lycopene increased by 1.8 times. However, the β-cryptoxanthin content was hardly affected by UV irradiation.

In plant tissues, carotenoid pigments are well known for their antioxidant function. For example, the main function of carotenoid pigments in photosynthetic tissue is to prevent the generation of radicals by the light energy absorbed by chlorophyll or to eliminate the generated radicals (McKersie and Lesham, 1994). Among these carotenoid pigments, especially lycopene has been reported to have the strongest radical scavenging activity (Rice-Evans et al., 1997). In plant cells, DNA molecules are most susceptible to ultraviolet radiation, resulting in damage to thymine bases (formation of thymine dimers) upon exposure to ultraviolet light (Landry et al. 1997). (Britt, 1996), reactive oxygen species produced during photooxidation act as a major factor in cell damage following UV exposure (Jansen et al., 1998). However, if UV damage is not fatal, cells are known to activate DNA repair mechanisms, as well as to activate enzymatic or non-enzymatic antioxidant systems to eliminate free radicals and other radicals. (Jansen et al., 1998). Therefore, the increase in the carotenoid content in the persimmon fruit irradiated with ultraviolet rays and thus the pigmentation could be interpreted to be related to the activation of the antioxidant mechanism of cells by UV hormesis.

<Ultraviolet irradiation and 1- MCP  Changes in Pigment Content and Pulp Hardness with Treatment>

When UV rays were irradiated on floating persimmon fruit, the production of ethylene did not increase immediately, but significantly increased after 2 weeks of storage at room temperature compared to no treatment, and the respiratory volume of fruit was increased immediately by UV irradiation and continuously high during storage. Was maintained (FIG. 4). This suggests that UV irradiation acted as a stressor for persimmon fruit, resulting in changes in intracellular metabolism. On the other hand, in the untreated fruit, the hardness of the flesh gradually decreased during storage at room temperature, and then rapidly decreased until the increase of ethylene production was increased, especially when ultraviolet stress was applied (FIG. 5). The softening of the flesh in the persimmon fruit is a common phenomenon caused by the action of ethylene, and it is necessary to confirm whether the enhancement of skin pigmentation by ultraviolet treatment is caused by the action of stress ethylene as well as the promotion of softening of the flesh. Therefore, as a result of irradiating ultraviolet rays to the fruit treated with 1-MCP, the softening of the flesh was significantly delayed (FIG. 5), but the carotenoid content change was hardly affected by the 1-MCP treatment (FIG. 3). This implies that the softening of the post-harvest flesh in persimmon fruit is closely associated with the action of ethylene (Nakano et al., 2001; Choi, 2010), whereas the increase in carotenoid synthesis and the enhancement of skin pigmentation were not affected by ethylene.

From the practical point of view of the present invention, when 1-MCP and ultraviolet irradiation are treated in parallel with persimmon fruit after harvesting, the softening of the flesh caused by UV stress is suppressed, and the coloring is enhanced by increasing the carotenoid content. It shows that it is possible to effectively improve quality.

According to the present invention, after irradiation with 1-MCP, an ethylene agonist, when the ultraviolet persimmon was irradiated to the floating persimmon fruit, the change of ethylene production, respiration, and pulp hardness with changes in carotenoid pigment content were investigated. As a result, the major carotenoid pigments of floating persimmon fruit were β-carotene, lycopene and β-cryptoxanthin at the time of harvest, but the lycopene pigment content increased significantly during storage at room temperature after harvesting. It was confirmed that the pigmentation of the skin was increased by increasing the content of the and lycopene pigments, but at the same time, the hardness of the flesh was reduced due to UV stress. Therefore, the increase of the carotenoid pigment content by UV irradiation was not affected by 1-MCP treatment. On the other hand, the softening of the pulp has the effect of confirming that it is significantly delayed by 1-MCP treatment. When the 1-MCP treatment and UV irradiation are combined with the floating persimmon fruit after harvesting, it is determined that the quality can be improved by suppressing softening and improving the coloration of the pericarp.

Claims (3)

delete Persimmon fruit, which is treated with 1 ppm methyl 1-methylcyclopropene (1-MCP) at a concentration of 1 ppm after harvesting and sealed for 16 hours, is irradiated with ultraviolet rays for 2 minutes using an ultraviolet (UV) lamp at a distance of 15 cm from the fruit. To increase skin pigmentation and prevent softening.
Persimmon fruit, characterized in that the beta-carotene and lycopene content is increased by the process of parallel treatment of 1-MCP and ultraviolet rays of claim 2.

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