AJCS 18(07):425-433 (2024) ISSN:1835-2707

https://doi.org/10.21475/ajcs.24.18.07.pne-67

Maintenance of post-harvest antioxidant quality in ‘Niagara Rosada’

grape using salicylic acid

Francisco José Domingues Neto

, Adilson Pimentel Junior

, Lilian

Massaro Simonetti

, Lenon Romano Modesto

, Fernando Ferrari Putti

Cristine Vanz Borges

, Giuseppina Pace Pereira Lima

, Marco Antonio

Tecchio

Department of Horticulture, School of Agronomy, São Paulo State

University, 18618 000, Botucatu, São Paulo, Brazil

Centro Universitário das Faculdades Integradas de Ourinhos, 19900

080, Ourinhos, São Paulo, Brazil

Federal University of Santa Catarina, Road Admar Gonzaga,

Florianópolis 88040-900, SC, Brazil

São Paulo State University, Tupã, Postal Code 17602-496, SP, Brazil

Department of Chemical and Biological Sciences, Institute of

Biosciences, São Paulo State University, 18618 000, Botucatu, São Paulo,

Brazil

Abstract: Salicylic acid is a plant growth regulator used

in grapes to maintain postharvest quality. ‘Niagara

Rosada’, a table grape, although much appreciated for

its flavor, has a short shelf life. We evaluated the

influence of postharvest application of different doses

Submitted:

11/12/2023

Revised:

07/03/2024

Accepted:

07/05/2024

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of salicylic acid on the quality of ‘Niagara Rosada’ after

harvest in an effort to control rates of berry drop and

decay, as well as to maintain the quality of grape

bunches during refrigerated storage. Freshly harvested

bunches of ‘Niagara Rosada’ (

Vitis labrusca

V. vinifera

)

were immersed in salicylic acid solutions at

concentrations of 0.0, 0.28, 0.55, 0.83, and 1.10 g L

-1

and then refrigerated (5 ± 1 °C and 95 ± 5 % RH) for 20

days. Physical and chemical analyses of grapes were

performed at 5-day intervals. Salicylic acid maintained

the postharvest quality of ‘Niagara Rosada’ grapes

throughout storage. The lowest concentration of

salicylic acid (0.28 g L

-1

) effectively induced the

synthesis of phenolic compounds and improved the

antioxidant capacities of both grapes and stems. High

levels of salicylic acid (0.83 and 1.10 g L

-1

) resulted in

an increase in anthocyanin content in fruit and enzyme

activities (peroxidase and superoxide dismutase) in

stems, enhancing conservation and reducing levels of

decay and berry drop.

Keywords: decay; berry drop; cold storage; phenolic compounds;

enzymes.

Introduction

Throughout the world, vine management techniques have been

researched in order to increase productivity and improve the postharvest

quality of grapes, including those destined for the table. Table grape

quality is dependent on both cultivar type and management practices

employed from flowering to harvest. ‘Niagara Rosada’ vines are

medium-vigor plants and are known to be resistant to various pests and

diseases. ‘Niagara Rosada’ grapes are pink-film fruits covered with a

waxy bloom, featuring mucilaginous pulp and a sweet foxed flavor that

is appreciated by consumers. Due to their high degree of acceptance in

the domestic market, these American table grapes have been cultivated

in areas where diseases have caused serious damage to vines (Maia and

Camargo, 2012).

In order to be acceptable to consumers, fruits must have high

postharvest quality. Table grapes with darkened stems from tissue

oxidation, softened texture, dehydrated berries, berry drop, or other

undesirable features will be declined, and their economic value will

depreciate. Several techniques have been used in pre- and postharvest

table grapes to reduce the incidence of berry decay, decrease softening

rates, prevent rotting during storage, and extend shelf-life. Among

these techniques, the use of plant growth regulators, such as salicylic

acid, is attractive since it can be safely and easily applied. Salicylic acid

(SA) or 2-hydroxybenzoic acid, is a plant growth regulator with a

phenolic structure that plays a crucial role in the regulation of fruit

development, growth, and ripening (Pérez-Llorca et al., 2019), as well as

in plant resistance to biotic and abiotic stresses (Hassoon and

Abdulsattar Abduljabbar, 2020). One of the most important functions of

salicylic acid in plants is to stimulate the production of compounds that

scavenge free radicals, called antioxidants (Hassoon and Abduljabbar,

2020). It is an important secondary metabolite produced by grapes and

plays an essential role in the determination of berry quality, affecting

color, flavor, astringency, and bitterness (Blanch et al., 2020). The

effects of SA rely on the synthesis of phenolic compounds, especially the

activity of the phenylalanine ammonia lyase enzyme (PAL). In addition,

recent research has indicated that SA has the potential to improve

physical properties such as size, weight, and fruit firmness.

Despite its great potential for use as a table grape, information

regarding the effect of exogenous application of plant regulators on

postharvest fruit quality in ‘Niagara Rosada’ is scarce. Several studies

have indicated that the exogenous application of SA improves important

postharvest characteristics, such as enhancing antioxidant capacity

(Gomes et al., 2021; Wang et al., 2015). SA may induce the inhibition of

catalase (CAT), a hydrogen peroxide scavenging enzyme, resulting in an

increase in levels of H2O2, which acts as a second messenger activating

defense-related genes (Chen et al., 1993). Exogenous SA in grape

Vitis

vinifera

L. cv. Jingxiu promoted an increase in superoxide dismutase

(SOD) and peroxidase (POD) activities, although there was an increase in

hydrogen peroxide, and this effect was attributed to the high rate of

H2O2 production compared to its degradation by the enzyme (Wang and

Li, 2006).

Furthermore, SA is related to disease resistance and shelf life (Gomes et

al., 2021) in horticultural crops. Important fruit quality characteristics

(e.g., sweetness, firmness, and color), which depend on the cultivar

used, as well as pre- and postharvest factors (Lo’ay et al., 2019; Xu et

al., 2019), have not been previously described in ‘Niagara Rosada’. Thus,

the aim of this research was to evaluate the influence of exogenous

application of salicylic acid on the postharvest of 'Niagara Rosada'

grapes on physical-chemical properties, as well as to assess antioxidant

compounds (enzymatic and non-enzymatic) of bunches during cold

storage.

Results and Discussion

Physical, chemical and biochemical characteristics of berries

Throughout storage, there was an increase in TA and a decrease in pH in

the fresh berries (Fig. 1A and 1C). However, SA did not significantly

affect the levels of titratable acidity (TA) or pH (Fig. 1B and 1D), and the

differences observed were exclusively based on the duration of storage.

Other studies demonstrate that exogenous SA does not influence the

content of TA and pH, as described by Gomes et al. (2021) in 'Niagara

Rosada' grapes treated with different doses of SA and by Alrashdi et al.

(2017) in ‘El-Bayadi’ table grapes. On the other hand, in seedless grapes

('Superior Seedless'), Lo’ay (2017) found a decrease in TA in response to

SA. Thus, it is possible that the acid content may be dependent on the

genotype, also influenced by the culture method, among other biotic and

abiotic factors. This may explain the slight changes that were observed

in ‘Niagara Rosada’ grapes throughout storage that occurred

independently of SA application.

Salicylic acid treatment effectively maintained soluble solids (SS) content

in ‘Niagara Rosada’ grapes throughout storage (Fig. 1E), and a

significant interaction between SA level and duration of storage was

observed. The SA dose affected SS levels of grapes subjected to all

durations of storage, except grapes assessed five days postharvest. A

concentration of 0.28 g L

-1

SA was found to be sufficient for maintaining

SS content. This result is significant because ‘Niagara Rosada’ is a table

grape, and the SS content is crucial for the flavor of this cultivar. It is

worth mentioning that grapes subjected to storage and SA treatments

had SS content greater than the minimum quantity required by Brazilian

legislation for table grapes (14° Brix) (Brasil, 2018).

Berry drop, decay, and weight loss were not significantly affected by SA

treatment (Fig. 2B, 2D, and 2F). The results clearly indicated that the

highest incidence of berry drop, decay, and weight loss occurred in

‘Niagara Rosada’ grapes after 20 days of storage. During this time,

stems had darkened due to oxidative processes, and low enzymatic

activity was observed, regardless of the SA treatment. After 20 days of

storage, the grapes did not show commercial quality (visual quality) and

should be discarded. In this study, we did not observe that any specific

concentration of SA might influence berry drop, weight loss, or decay, as

described by Gomes et al. (2021), who stated that 1 mmol L

-1

SA in the

pre-harvest was efficient in maintaining the quality of ‘Niagara Rosada’

grapes. The results obtained in this study may be attributed to the

dosages used, and probably smaller doses of SA may be more efficient

in decreasing berry drop, weight loss, and decay.

Although SA did not significantly influence the physical characteristics of

grapes assessed, 0.28 g L

-1

(2 mmol L

-1

) SA promoted an enhancement

in total phenolic compounds (221.75 mg 100 g-1) (Fig. 3A) and

antioxidant capacity measured by FRAP (172.93 mmol Fe Kg -1) (Fig. 3C)

after five days of storage. Higher levels of SA induced anthocyanin

content (Fig. 3B). On the other hand, there was no influence on the levels

of SA used in the antioxidant activity measured by the DPPH method

(Fig. 3E). In accordance with our findings and previous studies (Gomes et

al., 2021) in ‘Niagara Rosada’, it has been indicated that SA treatment of

pre- and postharvest table grapes facilitates the maintenance of quality

by minimizing loss of firmness and inducing the expression of

antioxidant compounds, characteristics that have been associated with

ripening processes and quality attribute loss. In our study, the highest

levels of total phenolic compounds and anthocyanins were found in

‘Niagara Rosada’ grapes after treatment with 0.28 g L

-1

SA (Fig. 3A and

3B), similar to that described by Alrashdi et al. (2017) in table grapes.

This effect may be attributed to phenylalanine ammonia-lyase activity

(PAL), whose product is phenylpropanoids (Chen et al., 2006), because

the transcription of the PAL genes may be activated by SA (Kiselev et al.,

2010).

Immersion of ‘Niagara Rosada’ grapes in high levels of SA (0.83 and 1.10

g L

-1

) further enhanced anthocyanin content (15.4 mg 100 g

-1

and 17.1

mg 100 g

-1

, respectively) five days postharvest (Fig. 3B). Anthocyanin is

principally responsible for grape skin coloration, which is a characteristic

significantly correlated with grape quality. Increased levels of these

compounds positively affect grape quality. Phenolic compounds,

including anthocyanins, are secondary metabolites that influence grape

qualities such as color, flavor, bitterness, and astringency, as well as the

antimicrobial and antioxidant properties of fruits. Previous studies

demonstrate that the application of SA induced the accumulation of

phenolic compounds, such as flavonoids and anthocyanins (Gomes et al.,

2021). In our study, SA exogenous increased the shelf life and the

phenolic