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PAPER 
 
 
 
 
 

CHLORINE DIOXIDE GAS TREATMENT 
ON POSTHARVEST QUALITY OF RASPBERRY 

 
 
 

M. MAGHENZANI, V. CHIABRANDO*, N. GIUGGIOLI, C. PEANO 
and G. GIACALONE 

Department of Agricultural, Forest and Food Sciences (DISAFA), Università degli Studi di Torino, Largo 
Paolo Braccini 2, 10095 Grugliasco, TO, Italy 

*Corresponding author. Tel.: +39 0116708938; fax: +39 0116708658 
E-mail address: valentina.chiabrando@unito.it 

 
 
 
 
 
 

ABSTRACT 
 
The study investigated the effects of chlorine dioxide (ClO2) gas on the postharvest quality 
of raspberries (cv Grandeur) during storage. Weight loss, color, total soluble solids content 
(TSSC), titratable acidity (TA), pH, vitamin C, total phenols, anthocyanins and antioxidant 
capacity were evaluated. The ClO2 positively influenced weight loss, color, TA, TSSC and 
antioxidant capacity. Moreover, ClO2 treatment decreased the total yeast and mold count. 
In contrast, the vitamin C, anthocyanins and total phenolics were not influenced by the 
ClO2 treatment. 
 
 
 
 
 

Keywords: chlorine dioxide, fruit quality, pad, postharvest, red raspberries, storage 
 

  



	

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1. INTRODUCTION 
 
Red raspberries (Rubus idaeus L.) are rich in ascorbic acid, total phenols and anthocyanins. 
Therefore, consumption of these berries is an important source of antioxidant compounds 
with a significant role in the preservation and promotion of health, such as preventing 
diabetes, cardiovascular risk factors and oxidative stress (ATIENZA et al., 2015; SEN and 
CHAKRABORTY, 2016). Red raspberry is a highly perishable product in which 
modification of quality compounds are related to the growth of microorganisms, and 
natural decay (GIACALONE and CHIABRANDO, 2012). Raspberry harvest and storage 
are complex operations and can affect the quality and aroma compounds of the fruit 
(GIUGGIOLI et al., 2014). Thus, the raspberry postharvest control strategies are critical to 
preserving the fruit quality, particularly on a long distribution chain (BRIANO et al., 
2015a; HAFFNER et al., 2002). Many technologies, like active packaging, modified 
atmosphere packaging, edible coating, Difolatan, hexanal, vapor essential oils or sanitizer 
treatments, such as chlorine dioxide (ClO2) and ozone have been studied to reduce the 
growth of microorganism, control postharvest decay and preserve the quality and 
freshness of berries (APPENDINI and HOTCHKISS, 2002; BRIANO et al., 2015b; 
CHIABRANDO and GIACALONE, 2008; CHIABRANDO and GIACALONE, 2015a; 
HAJIZADEH and KAZEMI, 2012; SUN et al., 2014).  
Chlorine dioxide is an alternative sanitizer, approved by the U.S. Food and Drug 
Administration (FDA) and by the U.S. Environmental Protection Agency (EPA). ClO2 is 
legally used in China and USA for sanitizing fruit and vegetables (Ministry of Health of 
the People's Republic of China, 2008 and USFDA, 2010). Particularly, ClO2 is authorized in 
the US for use in washing, whole fresh fruit, vegetables, shelled beans and peas with intact 
cuticles at a concentration not exceeding 5ppm.  In EU, however, there are no clear 
regulations regarding the use of ClO2 for fresh produce. Therefore, as a provisional 
solution, it was agreed that the individual member states will be given the ability to 
establish enforcement levels at the national level until risk management can take place 
based on European Food Safety Authority (EFSA) scientific opinion and monitoring data 
(BANACH et al., 2015). ClO2 has been postulated as an alternative to sodium hypochlorite 
(NaClO) for fresh and fresh-cut produce sanitization. CORDIS (Community Research and 
Development Information Service), designing new decontamination approaches for fresh-
cut food and sanitation strategies, include ClO2 among the most promising sanitation 
methods. 
In the European Union, ClO2 can be used in other forms, like active packaging, as a gas-
generating pad (DUKAN et al., 1999). The active substances of the pad are molecules of 
HClO (hypochlorous acid), found in silica gel and toxic to microorganisms. Chlorine 
dioxide gas is also a great sanitizer for food, at low concentration (CHEN et al., 2010; 
CHANG et al., 2000). The principal advantage of ClO2 gas is its high penetrability (HAN et 
al., 2001). Different studies (CHEN et al., 2010; CHANG et al., 2000) showed the positive 
effects of gaseous ClO2 on the storage quality of lettuce, mulberries, plums and 
strawberries. 
The objective of this study was to evaluate the impact of ClO2 treatment as a pad applied 
on the top lids of the clamshells, on the postharvest quality, nutraceutical aspects and 
microbiological decay of raspberries during four different storage conditions. 
 
 
 
 



	

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2. MATERIALS AND METHODS 
 
2.1. Samples and treatment 
 
Red raspberries (R. idaeus L.) cv. Grandeur were handpicked from a commercial orchard of 
the Agrifrutta Soc. Coop. SRL (Piedmont, Italy) at full ripeness and directly placed in 
commercial plastic boxes, clamshell type (13.5 x 9.0 x 2.5 cm, perforated, polyethylene 
terephthalate, 120 g of fruits). The samples were transported immediately to the laboratory 
of the DISAFA, University of Turin, and only sound fruit was selected for the experiment. 
The boxes were randomly divided into two groups. On one group, a chlorine dioxide gas-
generating pad (CDP) (Oplon Pure Science, Ltd., Ness Tsiyona, Israel) was placed on the 
top lids of the clamshells (U.S. Food and Drug Administration (FDA)-approved 
technology). The second group was used as the control. The effect of the CDP on the 
berries quality and antimicrobial activities during storage were measured. Each treatment 
included three replicates. 
 
2.2. Storage treatments 
 
Samples were stored in the dark in a controlled temperature room, and four different 
storage conditions were evaluated: 
S1: 4 days at 1 °C (short storage) 
S2: 8 days at 1 °C (long storage) 
S3: 4 days at 1 °C and 3 days at 4 °C (short storage + short-range international transport) 
S4: 8 days at 1 °C and 3 days at 4 °C (long storage + short-range international transport) 
The hypothesized transport time was 3 days, simulating a refrigerated transport from Italy 
to Northern Europe.  
Three repetitions were performed for all chemical analyses each time. 
 
2.3. Weight losses 
 
Weight loss was determined by weighing the numbered samples boxes at the beginning of 
the experiment (time 0) and at the end of the four different storage conditions. The values 
were reported as the percentage of weight loss per initial boxes weight, as shown in 
equation (1).  
 
 

 % 𝑤𝑒𝑖𝑔ℎ𝑡 𝑙𝑜𝑠𝑠𝑒𝑠 = !"!#!$% !"#$!!!!"#$% !"#$!!
!"!#!$% !"#$!!

∗ 100 (1) 
 
 
2.4. Quality measurements 
 
The physicochemical quality attributes of the berries were measured at the beginning of 
the testing (time 0) and at the end of the four different storage conditions. 
 
2.4.1 Color 
 
The color of the berries was measured using a tristimulus CR-400 Chroma Meter (Konica 
Minolta Sensing, Inc. Osaka, Japan) with the D65 lamp and 2° observation angle. The 
instrument was calibrated against a standard white plate (Y = 93.7, x = 0.3158, y = 0.3321) 
before the analysis. Thirty measurements (30 berries) per treatment and sampling time 



	

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were made. The results were express as CIELAB (L*a*b*) color space. The L* values 
describe the lightness, and a* and b* values express the red-greenness and blue-
yellowness, respectively. The color of berries was also expressed as C* (chroma or 
saturation). This parameter indicates the color variation C* = [(a*)2 + (b*)2]1/2) (FRANCIS, 
1980). The reported values were the mean ± SD of 30 determinations. 
 
2.4.2 Total soluble solid content (TSSC), titratable acidity (TA) and pH 
 
For each treatment, a digital refractometer (Atago refractometer model PR-32; Atago Italia, 
Milan, Italy) was used to determine the TSSC (°Brix) in three undiluted filtered juice 
samples, each extracted from 30 berries. The instrument was calibrated against distilled 
water. The TA and pH were determined by adding 50 mL of distilled water into 10 ml of 
filtered juice and titrated with 0.1 N NaOH to pH 8.2 with an automatic titrator (Titration 
Workstation TitraLab AT1000 Series, Hach, Milan, Italy). Titration data were expressed as 
meq L-1.  
 
2.5. Extraction and evaluation of total anthocyanins content, total phenolic contents, 
and total antioxidant capacity 
 
The anthocyanins, phenolics and antioxidant capacity were determined on the fruit 
extracts, obtained using 12.5 ml of extraction solvent (500 ml of methanol, 28.3 ml 
nanopure water and 1.4 ml 37% HCl) and 5 g of fresh fruit. After 60 min at 25 °C under 
reduced light conditions, the extracts were homogenized at 24000 rpm for 1 min, with an 
Ultra-Turrax T-25 tissue homogenizer (Janke and Kunkel, IKA®-Labortechnik, Saufen, 
Germany) and centrifuged at 3000 rpm for 15 min (Centrifuge AVANTITM J-25, Beckman 
Instruments Inc.). The supernatant was recovered and stored at -26 °C. Three replicates for 
each treatment were performed at day 0 and at the end of the four different storage 
conditions. 
Anthocyanins were determined using the pH differential method of CHENG and BREEN 
(1991) by measuring the absorbance of the aqueous phase at 515 and 700 nm using a UV-
visible spectrophotometer (U-5100, Hitachi, Tokyo, Japan). Anthocyanins were estimated 
by the difference in absorbance at 515 and at 700 nm in buffer at pH 1.0 and 4.5, where 
A = (A515 – A700)pH1 – (A515 – A700)pH4.5. 
Results were expressed as mg cyanidin-3-glucoside per 100 g fresh berries.  
Total phenolics contents were quantified using the SLINKARD and SINGLETON protocol 
(1977) with Folin-Ciocalteu reagent. Absorbance was measured at 765 nm. The results 
were calculated as gallic acid equivalents (GAE) (mg GAE 100 g-1 of fresh berries). 
The antioxidant activities of the berries were measured by the ferric reducing antioxidant 
power assay, as described by BENZIE and STRAIN (1996), with some modifications 
(PELLEGRINI et al., 2003). Results were expressed as mmol Fe2+ kg-1 fresh berries.  
 
2.6. Extraction and evaluation of vitamin C 
 
The vitamin C content was performed in agreement with SANCHEZ-MORENO et al. 
(2003) and GONZALEZ MOLINA et al. (2008) at day 0 and after 4 and 8 days of storage. 
Fruit flesh (10 g) was homogenized in 10 ml of methanol/water (5:95 v/v) using an Ultra-
Turrax T-25 for 3 min. Then, the pH was adjusted to 2.2–2.4, and the extract was filtered 
through a C18 Sep-Pak cartridge (Waters Associates, Milford, MA, USA). The resultant 
solution was combined with 1,2-phenylenediamine dihydrochloride (Fluka Chemika, 
Neu-Ulm, Switzerland) for 37 min before HPLC analysis. Three replicate analyses of 10 
fruits were performed for each treatment. The chromatographic system (Agilent) was 



	

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equipped with a diode array detector and Kinetex-C18 column (4.6 x 150 mm, 5 µm, 
Phenomenex., Torrance, CA, USA) and controlled through HPLC online software 
(Agilent). The mobile phase (isocratic) consisted of 50 mM monobasic potassium 
phosphate and 5 mM cetrimide (Sigma-Aldrich Corporation, Saint Louis, USA) in 
methanol:water (v/v) 5:95. The flow rate of 0.9 ml/min. The temperature was 40 °C, and 
the detector was set at 261 nm for ascorbic acid (AA) and 348 nm for dehydroascorbic acid 
(DHAA). The vitamin C content (AA and DHAA contents) was expressed as mg 100 g-1 of 
fresh weight. All standards and reagents were of analytical purity and were purchased 
from Sigma Italiana SRL (Ozzano Emilia, Italy). 
 
2.7. Yeast and mold evaluation 
 
The yeasts and molds content was evaluated at day 0 and after 4 and 8 days of storage as 
described by the Compendium of Methods for the Microbiological Examination of Foods 
(VANDERZANT and SPLETTSTOESSER, 1992). A 30 g sample of fresh berries was 
blended with 270 mL of peptone buffered water (Sigma Italiana SRL, Italy) for 1 min in a 
Stomacher® bag using a blender (Stomacher®400 Circulator, Seward, Worthing, UK). Rose 
bengal agar (Sigma Italiana SRL, Italy) was used for the yeast and molds evaluations. All 
the plates were incubated at 30 °C for 5 days. Microbial counts were expressed as log 
colony forming units (CFU) g−1. 
 
2.8. Statistical analysis 
 
Analysis of variance (ANOVA) was performed on the data, and the means were compared 
by Tukey’s honestly significant differences test. The source of variation was the treatments 
(control and CDP) and the storage time. Differences between mean values were 
considered significant when p ≤ 0.05. SPSS software was used for all data analyses (SPSS 
Statistics version 22 IBM).  
 
 
3. RESULTS AND DISCUSSIONS 
 
3.1. Weight loss 
 
In general, raspberries are affected by considerable weight loss because the tissues are 
exposed to a high level of respiration and transpiration (KRÜGER et al., 2011). In the 
present study, low weight losses were observed in all the samples compared to previous 
studies (KRÜGER et al., 2011; HAFFNER et al., 2009). After 4 days of storage (S1), the 
weight loss of the CDP samples was 0.71%, which was significantly lower than the control 
(0.98%). Therefore, in this postharvest storage condition, the CDP positively influenced the 
weight loss of raspberries, maintaining lower values compared to the control, according to 
ADAY and CANER (2011). The same result was also obtained in the S3 and S4 storage 
conditions, with 1.16 and 2.13% weight loss, respectively of the CDP treated fruit, while 
the corresponding control values were 1.52 and 2.61%. The effect of ClO2 on the weight 
loss depends on the inactivity of the microbial population, the inhibition of enzyme 
activity, such as polyphenol oxidase, and the inhibition of respiration rate and ethylene 
biosynthesis (ADAY and CANER 2011; GUO et al., 2013; WANG et al., 2011; SUN et al., 
2014).  
 
 
 



	

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3.2. Quality measurements 
 
3.2.1 Color 
 
Color change is an important factor that affects the visual appearance and the postharvest 
quality of fresh raspberry fruit. The L* and C* values of raspberry after 4 and 8 days of 
storage are reported in Table 1. The L* values after 4 and 8 days of storage showed a 
significant decrease in both treatments (control and CDP treatment), compared to day 0. 
Significant differences were observed between treatments after 4 days of storage at 1 °C, 
with higher values of L* in the CDP treated berries (fruit with a higher luminosity). As 
described by KRÜGER et al. (2011) and SHIN et al. (2008), a decrease in lightness values 
during storage, indicates that the fruit became darker, less red and bluer with advance 
ripening. In the present work, samples treated with the CDP maintained the original color 
of the berries, in concurrence with the study of ADAY and CANER (2011) on strawberries. 
The ClO2 gas did not influence the lightness during the S3 and S4 storage conditions. In 
these instances, there were no significant differences (p ≥ 0.05) in L* value between the 
CDP treatment (L* 27.9 and 29.4 in S3 and S4, respectively) and the control (L* 28.4 and 
29.2 in S3 and S4, respectively). 
The C* values initially increased and then decreased during storage as shown in Table 1. 
Considering the short period of storage (S1), results showed significantly higher values for 
the CDP samples compared to the control. In this instance, the CDP treatment significantly 
improved the redness intensity of berries during storage. In previous studies, the CDP 
treatment caused no pigment degradation and consequently, no changes in external color 
of berries (ZHENG et al., 2008; GOMEZ LOPEZ et al., 2009). The same result was also 
obtained under the S4 storage condition, where the CDP samples showed C* values of 
23.3, which was significantly higher compared to the control (C* 20.8). 
 
 
Table 1. Effect of ClO2 on color parameters (Lightness and Chroma) of raspberries after 4(S1) and 8(S2) days 
of storage at + 1°C. The data are average of 30 replicates ± SD.  
 

Color Parameters  
Storage time (days) 

Treatments 0 4 8 
Lightness Control 35.1±1.9 aA 29.1±3.0  bB 29.8±1.74 aB 

(L*) Chlorine dioxide 35.1±1.9 aA 30.4±2.2 aB 30.0±2.24 aB 
Chroma Control 22.7±4.0 aB 25.9±4.5 bA 25.4±4.1 aA 

(C*) Chlorine dioxide 22.7±4.0 aB 28.9±5.3 aA 25.9±5.7 aA 
 
 
3.2.2 TSSC, TA and pH  
 
TSSC, TA and pH values after 4 (S1) and 8 (S2) days of storage are shown in Table 2. The 
TSSC values were significantly different between treatments after 4 and 8 days of storage 
at +1°C, while the differences were not significant under S3 and S4 conditions (data not 
shown). The higher TSSC levels in the control than CDP treated berries may be due to the 
higher respiration rate and weight losses and, consequently, more concentrated juice of 
the control berries. WU et al. (2011) showed that ClO2 treatment maintained the TSSC 
similar to the value recorded at harvest, which was better than untreated fruit, probably 
due to the reduction of postharvest infections.  
The TA decreased significantly during storage for both treatments, but without significant 
differences. The TA values decreased significantly for all samples during storage. In the 



	

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control samples, the lowest recorded TA value was under S4 conditions, and in the CDP 
sample, it was under S3 conditions. The decrease in TA and increase in TSSC during 
storage were associated with the enhancement of temperature from 1 to 4 °C in S3 and S4 
that caused an increase in respiration rate and the natural consumption of organic acids by 
the metabolism (HAFFNER et al., 2009). The changes in TA probably depended more on 
temperature than the effect of ClO2, according to the study of ADAY and CANER (2011) 
on strawberries (Table 2).  
The pH level increased in the control samples in agreement with the TA result, while in 
the CDP treated samples no significant differences were observed during storage. ADAY 
and CANER (2011) reported that ClO2 treatment maintained stable pH levels in samples 
during storage probably due to the antimicrobial activity of ClO2 on yeast and mold, and 
consequently, to the inhibition of natural decay. 
 
 
Table 2. Effect of ClO2 on quality parameters of raspberries after 4(S1) and 8(S2) days of storage at + 1°C. 
Total Soluble Solid Content (TSSC), Titratable Acidity (TA) and pH. The data are average of 3 replicates ± 
SD. 
 

 
 Storage time (days) 

Treatments 0 4 8 
TSSC Control 8.4±0.1 aB 9.0±0.3 aA 8.6±0.0 aB 
°Brix Chlorine dioxide 8.4±0.1 aA 8.3±0.2 bA 8.1±0.1 bA 
TA Control 447.65±17.1 aA 450.98±5.6 aA 390.83±17.6 aB 
meq/L Chlorine dioxide 447.65±17.1 aA 447.06±12.0 aA 402.03±8.1 aB 
pH Control 3.04±0.01 aB 3.07±0.01 aAB 3.10±0.04 aA 

 Chlorine dioxide 3.04±0.01 
aA 3.02±0.01 bA 3.16±0.12 aA 

 
Means sharing the same letters in rows (A, B) and in column (a, b) are not significantly different from each 
other (Tukey’s HSD test, p ≤ 0.05). 
 
 
3.3. Total anthocyanin content 
 
Total anthocyanin content is one of the functional constituents in raspberries that are 
associated with their bright red color. The content of anthocyanins increased during the 
storage at 1 °C (S1 and S2) (Table 3) and then decreased during storage at 4°C (S3 and S4). 
This trend may be due to the decomposition of procyanidins at the beginning of storage 
(Chun et al., 2013). The results of the present study agree with the research of HAFFNER et 
al. (2002) that reported a similar increase in anthocyanin content after 7 days of cold 
storage (1.7°C), but contrasts with the study of MULLEN et al. (2002) that did not show a 
significant increase during cold storage. Moreover, the results indicated that the content of 
anthocyanins increased in the same manner as the pH after 8 days of cold storage at 1 °C. 
According to ORAK (2007), a correlation exists between anthocyanins and pH in grapes. 
Hence, the current results suggest a similar trend in raspberries. Considering the 
treatment, ClO2 does not seem to directly influence the anthocyanins level because no 
significant differences between treatments were found.  
 
3.4. Total phenolics content 
 
As shown in Table 3, according to the total anthocyanin content results, no significant 
differences in total phenolic content were observed during storage time or between 



	

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treatments. In general, an increase in total phenols was observed throughout the storage. 
A similar result was also noted previously in raspberries (KRÜGER et al., 2011) in 
strawberries (CHENG and BREEN, 1991) and in blueberries (CHIABRANDO and 
GIACALONE, 2015b) and it seems to depend on the weight loss. In this work, the lack of 
significant difference between the CDP treated and control samples was probably due to 
the low level of ClO2. GOMEZ LOPEZ et al. (2009) and NAPOLITANO et al. (2005) found 
that a high level of ClO2 can react with phenolic compounds, decreasing their content in 
the food. Considering the storage at 4 °C (S3 and S4), the ClO2 gas did not influence the 
total phenolic content. Indeed, there were no significant differences (p ≥ 0.05) between the 
CDP treatment (202.24 and 232.26 mg GAE 100 g-1 in S3 and S4, respectively) and the 
control (216.31 and 240.95 mg GAE 100 g-1 in S3 and S4, respectively). 
 
 
Table 3. Effect of ClO2 on nutraceutical parameters of raspberries after 4(S1) and 8(S2) days of storage at    
+1 °C. The data are average of 3 replicates ± SD. 
 

 
 Storage times (days) 

Treatments 0 4 8 
Total anthocyanin content Control 43.62±6.65 aB 54.5±5.24 aAB 78.11±7.66 aA 

mg cyanidin 3-gluc100 g-1 FW Chlorine dioxide 43.62±6.65 aB 52.24±5.71 aAB 68.22±7.47 aA 
Total phenolics content Control 198.3±16.55 aA 235.66±19.44 aA 219.45±23.41 aA 

mg gallic acid equivalent (GAE)100 
g-1 FW Chlorine dioxide 198.3±16.55 

aA 217.65±17.33 aA 204.21±9.87 aA 

Total antioxidant capacity Control 27.81±2.35 aA 28.93±0.60 aA 30.96±1.25 aA 
mmol Fe2+kg-1 FW Chlorine dioxide 27.8±2.35 aA 28.11±1.42 aA 28.11±0.80 bA 
Vitamin C content Control 12.45±0.40 aA 12.97±1.09 aA 9.39±0.85 aB 

mg100 g−1 FW Chlorine dioxide 12.45±0.40 aA 12.87±0.57 aA 8.76±1.30 aB 
 
Means sharing the same letters in rows (A, B) and in column (a, b) are not significantly different from each 
other (Tukey’s HSD test, p ≤ 0.05). 
 
 
3.5. Total antioxidant capacity 
 
As shown in Table 3, the total antioxidant capacity increased slowly during storage. 
Statistical analysis showed significant differences between samples after 8 days of storage, 
with a higher value in the control than CDP treated sample. This result is in accordance 
with MULLEN et al. (2002) and KALT et al. (1999). Considering the storage at 4 °C (S3 and 
S4), the ClO2 did not influence the antioxidant capacity and there was no significant 
difference (p ≥ 0.05) between the CDP treatment (28.54 and 28.27 mmol Fe2+ kg-1 in S3 and 
S4, respectively) and the control (29.68 and 31.03 mmol Fe2+ kg-1 in S3 and S4, respectively).  
 
3.6. Vitamin C content 
 
Table 3 presents the vitamin C values of the untreated and treated samples after 4 and 8 
days of storage. The vitamin C content decreased over time in both treatments, but 
without statistical differences between treatments. A similar trend was observed in the 
study of HAFFNER et al. (2002) and KALT et al. (1999) during storage at 0 °C. According to 
KRÜGER et al. (2011), the AA content depends particularly on the storage conditions and 
the genotype of the plant. 
 



	

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3.7. Yeast and mold evaluation 
 
Raspberries are highly perishable and susceptible to microbial decay during postharvest 
storage. Therefore, decay is a primary factor of postharvest quality loss of raspberries, and 
a strategy is necessary to improve their shelf-life quality. No mold growth was visually 
observed during the present study. At day 0, the yeast and mold were present in relatively 
low amounts, at 2.9 and 4.2 log CFU/g-1, respectively (Table 4). After 4 and 8 days of 
storage at 1 °C, a reduced yeast and mold count was observed in the CDP treated samples 
compared to the control. The decay incidence of the raspberries gradually increased with 
time of storage only in the control samples. Hence, in this study, the CDP treatment was 
effective against the growth of yeast and mold throughout the storage period. This result 
was in agreement with the study of SUN et al. (2014) on blueberries. The same trend has 
also been found in lettuce, carrot, apples, peaches, tomatoes and fresh-cut produce (SY et 
al., 2005). 
 
 
Table 4. Effect of ClO2 on nutraceutical parameters of raspberries after 4(S1) and 8(S2) days of storage at 
+1°C. The data are average of 3 replicates ± SD. 
 

 Storage time (days) 

 Treatments 0 4 8 
Yeast Control 2.85 aB 4.88 aA 3.61 aA 

Log CFU g-1 Chlorine dioxide 2.85 aA 2.56 bA 2.60 bA 
Mold Control 4.20 aA 4.79 aA 4.41 aA 

Log CFU g-1 Chlorine dioxide 4.20 aA 2.38 bB 2.34 bB 
 
Means sharing the same letters in rows (A, B) and in column (a, b) are not significantly different from each 
other (Tukey’s HSD test, p ≤ 0.05). 
 
 
4. CONCLUSIONS 
 
The present study showed the action of ClO2 against the natural decay of raspberries and 
its efficacy in preserving berry quality under various postharvest storage conditions. 
Results suggest that ClO2 treatment in active packaging is useful to reduce decay and 
maintaining raspberry quality during storage. In particular, ClO2 slowed down the tissue 
metabolism and consequently, lower weight losses were found compared to the untreated 
fruit. Moreover, ClO2 treatment significantly improved the redness intensity of berries 
during storage, but no significant effect on maintaining the stability of nutraceutical 
components was recorded. In summary, the CDP can be a valuable alternative sanitizer 
with a beneficial action against yeast and mold without reducing the quality of the final 
produce. This treatment also improved the shelf-life quality by inhibiting the weight loss 
and the color changes of raspberries during short period storage time.  
 
 
ACKNOWLEDGEMENTS 
 
The study was supported by the University of Turin - Local research. 
 
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Paper Received November 28, 2016  Accepted March 6, 2017