1. bookVolume 66 (2021): Issue 4 (December 2021)
Journal Details
License
Format
Journal
eISSN
1508-5791
First Published
25 Mar 2014
Publication timeframe
4 times per year
Languages
English
access type Open Access

Effect of gamma irradiation on microbiological and nutritional properties of the freeze-dried berries

Published Online: 25 Nov 2021
Volume & Issue: Volume 66 (2021) - Issue 4 (December 2021)
Page range: 221 - 225
Received: 02 Dec 2020
Accepted: 19 Feb 2021
Journal Details
License
Format
Journal
eISSN
1508-5791
First Published
25 Mar 2014
Publication timeframe
4 times per year
Languages
English
Abstract

Lyophilization or freeze-drying is the technique of removing ice or other frozen solvents from a material through sublimation and the removal of bound water molecules through the process of desorption. Drying occurs in an absolute vacuum at temperatures from −40°C to −50°C. This technique is often used for the conservation of fruits, especially berries. During this process, the water changes from frozen to gaseous, with no thawing. Due to low temperatures and the high vacuum, most microorganisms are rendered inactive during the lyophilization process. However, if there is a necessity to destroy all microorganisms from treated food, subsequent irradiation with gamma rays is an appropriate method. This paper investigated the influence of different doses of gamma radiation on lyophilized berries’ microbiological characteristics. It was shown that the radiation dose of 7 kGy is sufficient to eliminate the total number of microorganisms (excluding molds) to the extent that the number falls below the permitted limit according t o the law on the microbiological safety of foodstuffs of the Republic of Serbia, and 5 kGy is enough for molds to be rendered inactive. It was also concluded that gamma irradiation does not affect the nutritional value of lyophilized berries.

Keywords

Introduction

Lyophilization, also known as freeze-drying or cryodesiccation, is a low-temperature dehydration process [1] that involves freezing the product, lowering pressure, and then removing the ice by process of sublimation [2, 3]. Freeze-drying is most used to make instant coffee [4] but works exceptionally well on fruits such as apples [5] and berries [6].

The lyophilization process avoids product contamination because most bacteria and molds cannot survive this process. Freeze-dried fruit is an excellent addition to oatmeal, muesli, honey, teas, and many other healthy food products [7].

Freezing does not remove all microorganisms and bacteria from food. It may decrease the number of bacteria, but many harmful bacteria can generally still survive. Therefore, an additional gamma irradiation method can be applied to remove microorganisms from freeze-dried fruit [8].

In this paper, gamma irradiation's influence on reducing the total number of microorganisms, molds, and bacteria was examined. For this purpose, five types of berries were tested:

Rubus fruticosus (blackberries)

Rubus idaeus (raspberries)

Fragaria ananassa (strawberries)

Vaccinium corymbosum (blueberries)

Prunus cerasus (sour cherries).

It was shown that the radiation dose of 7 kGy could eliminate the total number of microorganisms, molds, and bacteria below the permitted limit prescribed by the law on the microbiological safety of foodstuffs of the Republic of Serbia. These gamma irradiation doses do not affect the nutritional value of lyophilized berries.

Materials and methods
Sampling

Freshly harvested ripe fruits were purchased from the local green market in Belgrade, Serbia. The fruits were washed and dried at room temperature. The weight of each berry sample was 100 g. Dry samples of fruit were lyophilized.

Lipohylized berries were packed into sterilized zip bags and irradiated with different gamma radiation doses in the facility for radiation sterilization and conservation of the Vinca Institute of Nuclear Sciences.

Lyophilization

For the fruit lyophilization, the Home Freeze Dryer, Harvest Right, the USA were used. The freezing was done at −42°C, and after freezing, the ice was vacuum pumped out in 24 h. The vacuum pressure during freeze-drying was 20 Pa.

After the lyophilization process, the following values of berry powders were measured (Table 1).

Percentage of removed water during the process of lyophilization

Berry fruit Weight before lyophilization process (g) Weight after lyophilization process (g) % of removed water
Blackberries 1000 121 87.9
Raspberries 1000 142 85.8
Strawberries 1000 90 91.0
Blueberries 1000 163 83.7
Sour cherries 1000 180 82.0
Gamma irradiation

During gamma irradiation, high-energy photons, generated from the radioactive source Co-60, penetrate through the product and destroy the DNA chains in living organisms that thrive in the product (insects, molds, yeasts, and bacteria). Radiation doses of 3 kGy, 5 kGy, and 7 kGy were used. The average dose rate was 10 kGy/h.

For the measurement of absorbed radiation dose, we used the ethanol-monochlorobenzene (ECB) dosimeter system [9, 10]. Measuring equipment for ECB is the instrument OK-302/2 type oscillotitrator of Radelkis (Budapest, Hungary). Since the oscillotitrator's measurement [11] is highly temperature-dependent [12], all dosimeters are heated to 20°C.

Microbiological analysis

The initial contamination and the number of microorganisms, total molds, and bacteria in the samples were examined in the accredited microbiology laboratory, using the methods Ph. Eur. 7.0 (2.6.12. – microbiological examination of nonsterile products (total viable aerobic count)) [13]. Microbiological analyses were performed before irradiation and after gamma irradiation with radiation doses of 3 kGy, 5 kGy, and 7 kGy.

Nutritional properties

The samples of freeze-dried berries before and after gamma irradiation were analysed to determine their content of total fat, water, protein, carbohydrates, sugars, dietary fiber, and energy values. The total fat content was determined by Weibull–Stoldt-Standard application [14]. The berries’ water content was analysed using an electronic water content analyser that works on drying with air circulation. Protein content was determined using a standard ISO procedure, ISO 1871:2009 [15], and the Kjeldahl method [16]. Determination of total carbohydrate and sugars present in freeze-dried berries was performed using the phenol sulfuric acid method [17]. An enzymatic-gravimetric method was used to determine the content of dietary fiber in freeze-dried berries samples.

Results and discussion
Weight loss

Some studies have shown that with the irradiation treatment, the berries lose weight [18]. Weight changes were not observed in our case, which shows that the weight lost during irradiation depends on the sample's water content. In this case, all the water was eliminated by the lyophilization process.

Effect of gamma irradiation on microbiological properties

To eliminate total microorganisms, molds, and bacteria from freeze-dried berries, they were treated with gamma irradiation doses of 3 kGy, 5 kGy, and 7 kGy. The measured absorbed radiation doses were (3 ± 0.12) kGy, (5.0 ± 0.22) kGy, and (7.1 ± 0.18) kGy. The uniformity of the delivered dose was 3.6%.

The content of the total number of microorganisms was translated into a radiation dose curve, which represents a logarithmic variation of the total number of microorganisms as a function of the absorbed radiation dose (Fig. 1).

Fig. 1

Influence of different doses of gamma radiation on the total number of microorganisms in samples of freeze-dried berries. The red line represents the limit of the permissible value.

Figure 1 shows that the radiation dose of 7 kGy is enough to eliminate the total number of microorganisms below the permitted limit. Similar results are shown in the literature [19].

Table 2 shows that the radiation dose of 5 kGy is enough to eliminate the total molds below the permitted limit, as reported in the previous research [20].

The total number of molds before and after the influence of different doses of gamma irradiation

Total mold (cfu·g−1) Dose (kGy) Permissible value

0 3 5 7
Blueberries 810 130 <100 <100 <100
Blackberries 740 110 <100 <100 <100
Raspberries 530 <100 <100 <100 <100
Strawberries 640 <100 <100 <100 <100
Sour cherries 550 110 <100 <100 <100

None of the six tested bacteria (Salmonella sp., Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus cereus, Sulfitoreducing clostridia) were found in the samples, either before or after irradiation.

Effect of gamma irradiation on nutritional values of samples

Several studies have confirmed that doses up to 10 kGy do not cause any toxicological hazards or nutritional and microbiological problems in fresh berries [21]. To determine the gamma irradiation influence on the nutritional properties of freeze-dried berries, we performed an analysis in the non-irradiated samples and the samples irradiated with the irradiation dose of 3 kGy, 5 kGy, and 7 kGy. The data are shown in Tables 3–7.

Nutritional values of freeze-dried blueberries

Parameter/Dose 0 kGy 3 kGy 5 kGy 7 kGy
Total fat (%) 0.34 0.43 0.73 1.30
Water (%) 5.2 5.4 5.4 5.6
Protein (%) 6.0 6.1 6.2 6.2
Carbohydrate (%) 86 86 85 84
Sugars (%) 48.2 48.5 47.7 48.8
Dietary fiber (%) 10.9 11.3 11.1 10.8
Energetic value (kJ) 1593 1598 1594 1599

Nutritional values of freeze-dried blackberries

Parameter/Dose 0 kGy 3 kGy 5 kGy 7 kGy
Total fat (%) 0.59 0.63 0.71 0.69
Water (%) 4.7 4.5 5.3 4.8
Protein (%) 6.0 6.1 6.3 6.2
Carbohydrate (%) 86 87 86 86
Sugars (%) 43.0 42.1 43.2 43.0
Dietary fiber (%) 14.1 14.3 13.9 15.1
Energetic value (kJ) 1603 1623 1611 1616

Nutritional values of freeze-dried raspberries

Parameter/Dose 0 kGy 3 kGy 5 kGy 7 kGy
Total fat (%) 0.65 0.62 0.84 0.61
Water (%) 7.0 7.3 7.2 7.3
Protein (%) 7.1 7.1 7.2 7.3
Carbohydrate (%) 83 83 81 82
Sugars (%) 47.7 46.5 47.0 46.8
Dietary fiber (%) 19.8 20.1 20.1 20.6
Energetic value (kJ) 1572 1571 1547 1557

Nutritional values of freeze-dried strawberries

Parameter/Dose 0 kGy 3 kGy 5 kGy 7 kGy
Total fat (%) 0.67 0.62 0.58 0.59
Water (%) 5.9 6.1 6.1 6.1
Protein (%) 5.9 6.0 6.1 6.0
Carbohydrate (%) 85 85 85 85
Sugars (%) 57.6 57.0 58.0 57.8
Dietary fiber (%) 9.7 10.1 9.8 9.9
Energetic value (kJ) 1587 1587 1587 1586

Nutritional values of freeze-dried sour cherries

Parameter/Dose 0 kGy 3 kGy 5 kGy 7 kGy
Total fat (%) 0.22 0.33 0.21 0.48
Water (%) 7.8 7.9 8.3 8.1
Protein (%) 8.1 8.1 8.2 8.2
Carbohydrate (%) 82 81 81 81
Sugars (%) 52.4 50.0 50.0 51.0
Dietary fiber (%) 8.7 9.1 9.2 9.0
Energetic value (kJ) 1666 1643 1640 1660

It can be inferred that the changes in most nutritional were insignificant and within the limits of measurement error. The exception is the total fat content in the samples. Its values vary and do not follow any trend; so, we can assume that their detection method is quite unreliable at such a low amount of total fat content in the samples.

Conclusions

Lyophilization is an effective method for preserving food. It is a widely used method to preserve berries. Exposure to low temperatures and vacuum during the lyophilization process removes most microorganisms from the berries. A highly effective method for the complete elimination of microorganisms from lyophilized fruit is high-energy gamma radiation. This study aimed to determine the radiation dose required to eliminate all microorganisms, molds, and bacteria from freeze-dried berries.

It was found that the process of lyophilization eliminates different percentages of water from berries, from 82.0% to 91.0%. The irradiation process does not affect the weight loss of the freeze-dried berries. As the radiation dose increases, the total number of microorganisms and molds in all tested samples decreases. A dose of gamma radiation of 3 kGy eliminates 85–89% of the total microorganisms in the samples, while a dose of 5 kGy is sufficient to eliminate over 97% of microorganisms. It was determined that a dose of 7 kGy is enough to eliminate all microorganisms.

On the other hand, a dose of 3 kGy destroys most mold, while 5 kGy is enough to eliminate all mold from freeze-dried fruit. The influence of gamma radiation on the change of nutritional values of samples was also investigated. It has been shown that gamma radiation does not affect the change in freeze dried berries’ nutritional values. The only deviation was established in the percentage of fat. Still, their content in dried berries is small, and the differences in values can be attributed to measurement errors and uncertainty of the method.

Fig. 1

Influence of different doses of gamma radiation on the total number of microorganisms in samples of freeze-dried berries. The red line represents the limit of the permissible value.
Influence of different doses of gamma radiation on the total number of microorganisms in samples of freeze-dried berries. The red line represents the limit of the permissible value.

Nutritional values of freeze-dried blueberries

Parameter/Dose 0 kGy 3 kGy 5 kGy 7 kGy
Total fat (%) 0.34 0.43 0.73 1.30
Water (%) 5.2 5.4 5.4 5.6
Protein (%) 6.0 6.1 6.2 6.2
Carbohydrate (%) 86 86 85 84
Sugars (%) 48.2 48.5 47.7 48.8
Dietary fiber (%) 10.9 11.3 11.1 10.8
Energetic value (kJ) 1593 1598 1594 1599

Percentage of removed water during the process of lyophilization

Berry fruit Weight before lyophilization process (g) Weight after lyophilization process (g) % of removed water
Blackberries 1000 121 87.9
Raspberries 1000 142 85.8
Strawberries 1000 90 91.0
Blueberries 1000 163 83.7
Sour cherries 1000 180 82.0

Nutritional values of freeze-dried raspberries

Parameter/Dose 0 kGy 3 kGy 5 kGy 7 kGy
Total fat (%) 0.65 0.62 0.84 0.61
Water (%) 7.0 7.3 7.2 7.3
Protein (%) 7.1 7.1 7.2 7.3
Carbohydrate (%) 83 83 81 82
Sugars (%) 47.7 46.5 47.0 46.8
Dietary fiber (%) 19.8 20.1 20.1 20.6
Energetic value (kJ) 1572 1571 1547 1557

Nutritional values of freeze-dried blackberries

Parameter/Dose 0 kGy 3 kGy 5 kGy 7 kGy
Total fat (%) 0.59 0.63 0.71 0.69
Water (%) 4.7 4.5 5.3 4.8
Protein (%) 6.0 6.1 6.3 6.2
Carbohydrate (%) 86 87 86 86
Sugars (%) 43.0 42.1 43.2 43.0
Dietary fiber (%) 14.1 14.3 13.9 15.1
Energetic value (kJ) 1603 1623 1611 1616

Nutritional values of freeze-dried strawberries

Parameter/Dose 0 kGy 3 kGy 5 kGy 7 kGy
Total fat (%) 0.67 0.62 0.58 0.59
Water (%) 5.9 6.1 6.1 6.1
Protein (%) 5.9 6.0 6.1 6.0
Carbohydrate (%) 85 85 85 85
Sugars (%) 57.6 57.0 58.0 57.8
Dietary fiber (%) 9.7 10.1 9.8 9.9
Energetic value (kJ) 1587 1587 1587 1586

Nutritional values of freeze-dried sour cherries

Parameter/Dose 0 kGy 3 kGy 5 kGy 7 kGy
Total fat (%) 0.22 0.33 0.21 0.48
Water (%) 7.8 7.9 8.3 8.1
Protein (%) 8.1 8.1 8.2 8.2
Carbohydrate (%) 82 81 81 81
Sugars (%) 52.4 50.0 50.0 51.0
Dietary fiber (%) 8.7 9.1 9.2 9.0
Energetic value (kJ) 1666 1643 1640 1660

The total number of molds before and after the influence of different doses of gamma irradiation

Total mold (cfu·g−1) Dose (kGy) Permissible value

0 3 5 7
Blueberries 810 130 <100 <100 <100
Blackberries 740 110 <100 <100 <100
Raspberries 530 <100 <100 <100 <100
Strawberries 640 <100 <100 <100 <100
Sour cherries 550 110 <100 <100 <100

Lombrana, J. I. (2008). Fundamentals and tendencies in freeze-drying of food. In C. Ratti (Ed.), Advances in food dehydration (Chapter 8, pp. 209–235). CRC Press. LombranaJ. I. 2008 Fundamentals and tendencies in freeze-drying of food In RattiC. (Ed.), Advances in food dehydration Chapter 8, 209 235 CRC Press 10.1201/9781420052534.ch8 Search in Google Scholar

Pisano, R., Arsiccio, A., Capozzi, L. C., & Trout, B. L. (2019). Achieving continuous manufacturing in lyophilization: Technologies and approaches. Eur. J. Pharm. Biopharm., 142, 265–279. DOI: 10.1016/j.ejpb.2019.06.027. PisanoR. ArsiccioA. CapozziL. C. TroutB. L. 2019 Achieving continuous manufacturing in lyophilization: Technologies and approaches Eur. J. Pharm. Biopharm. 142 265 279 10.1016/j.ejpb.2019.06.027 Open DOISearch in Google Scholar

Aksu, M. İ., Turan, E., & Şat, İ. G. (2020). Effects of lyophilized red cabbage water extract and pH levels on the quality properties of pastırma cemen paste during chilled storage. J. Stored Prod. Res., 89, 101696. DOI: 10.1016/j.jspr.2020.101696. AksuM. İ. TuranE. Şatİ. G. 2020 Effects of lyophilized red cabbage water extract and pH levels on the quality properties of pastırma cemen paste during chilled storage J. Stored Prod. Res. 89 101696 10.1016/j.jspr.2020.101696 Open DOISearch in Google Scholar

De Abreu Pinheiro, F., Ferreira Elias, L., de Jesus Filho, M., Uliana Modolo, M., de Cássia Gomes Rocha, J., Fumiere Lemos, M., & Soares Cardoso, W. (2021). Arabica and Conilon coffee flowers: bioactive compounds and antioxidant capacity under different processes. Food Chem., 336, 127701. DOI: 10.1016/j.foodchem.2020.127701. De Abreu PinheiroF. Ferreira EliasL. de Jesus FilhoM. Uliana ModoloM. de Cássia Gomes RochaJ. Fumiere LemosM. Soares CardosoW. 2021 Arabica and Conilon coffee flowers: bioactive compounds and antioxidant capacity under different processes Food Chem. 336 127701 10.1016/j.foodchem.2020.127701 Open DOISearch in Google Scholar

Lammerskitten, A., Wiktor, A., Siemer, C., Toepfl, S., Mykhailyk, V., Gondek, E., Rybak, K., Witrowa-Rajchert, D., & Parniakov, O. (2019). The effects of pulsed electric fields on the quality parameters of freeze-dried apples. J. Food Eng., 252, 36–43. DOI: 10.1016/j.jfoodeng.2019.02.006. LammerskittenA. WiktorA. SiemerC. ToepflS. MykhailykV. GondekE. RybakK. Witrowa-RajchertD. ParniakovO. 2019 The effects of pulsed electric fields on the quality parameters of freeze-dried apples J. Food Eng. 252 36 43 10.1016/j.jfoodeng.2019.02.006 Open DOISearch in Google Scholar

Różyło, R. (2020). Recent trends in methods used to obtain natural food colorants by freeze-drying. Trends Food Sci. Technol., 102, 39–50. DOI: 10.1016/j.tifs.2020.06.005. RóżyłoR. 2020 Recent trends in methods used to obtain natural food colorants by freeze-drying Trends Food Sci. Technol. 102 39 50 10.1016/j.tifs.2020.06.005 Open DOISearch in Google Scholar

Waghmare, R. B., Perumal, A. B., Moses, J. A., & Anandharamakrishnan, C. (2021). Recent developments in freeze drying of foods. In K. Knoerzer & K. Muthukumarappan (Eds.), Innovative food processing technologies: A comparative review (Vol. 3, pp. 82–99). Cambridge: Elsevier. DOI: 10.1016/b978-0-12-815781-7.00017-2. WaghmareR. B. PerumalA. B. MosesJ. A. AnandharamakrishnanC. 2021 Recent developments in freeze drying of foods In KnoerzerK. MuthukumarappanK. (Eds.), Innovative food processing technologies: A comparative review 3 82 99 Cambridge Elsevier 10.1016/b978-0-12-815781-7.00017-2 Open DOISearch in Google Scholar

Park, J. -N., Sung, N. -Y., Byun, E. -H., Byun, E. -B., Song, B. -S., Kim, J. -H., & Lyu, E. -S. (2015). Microbial analysis and survey test of gamma-irradiated freeze-dried fruits for patient's food. Radiat. Phys. Chem., 111, 57–61. DOI: 10.1016/j.radphyschem.2015.02.011. ParkJ. -N. SungN. -Y. ByunE. -H. ByunE. -B. SongB. -S. KimJ. -H. LyuE. -S. 2015 Microbial analysis and survey test of gamma-irradiated freeze-dried fruits for patient's food Radiat. Phys. Chem. 111 57 61 10.1016/j.radphyschem.2015.02.011 Open DOISearch in Google Scholar

International Organization for Standardization. (2009). ISO/ASTM 51538 – Practice for use of the ethanol-chlorobenzene dosimetry system. International Organization for Standardization 2009 ISO/ASTM 51538 – Practice for use of the ethanol-chlorobenzene dosimetry system Search in Google Scholar

Kovács, A., Stenger, V., & Fóldiák, G. (1987) Evaluation methods of the ethanol – monochlorobenzene dosimeter system. In P. Hedvig, L. Nyikos & R. Schiller (Eds.), Proceedings of the 6th Tihany Symposium on Radiation Chemistry (pp. 701–709). Budapest: Akadémiai Kiadó. KovácsA. StengerV. FóldiákG. 1987 Evaluation methods of the ethanol – monochlorobenzene dosimeter system In HedvigP. NyikosL. SchillerR. (Eds.), Proceedings of the 6th Tihany Symposium on Radiation Chemistry 701 709 Budapest Akadémiai Kiadó Search in Google Scholar

Kovács, A., Slezsák, I., McLaughlin, W., & Miller, A. (1995). Oscillometric and conductometric analysis of aqueous and organic dosimeter solutions. Radiat. Phys. Chem., 46(4/6), 1211–1215. DOI: 10.1016/0969-806x(95)00357-4. KovácsA. SlezsákI. McLaughlinW. MillerA. 1995 Oscillometric and conductometric analysis of aqueous and organic dosimeter solutions Radiat. Phys. Chem. 46 4/6 1211 1215 10.1016/0969-806x(95)00357-4 Open DOISearch in Google Scholar

Vujčić, I., Mašić, S., Spasevska, H., & Dramicanin, M. (2018). Accuracy of determining absorbed irradiation dose at different temperature measurements using ethanol-chlorobenzene oscillotitrator system. Nucl. Technol. Radiat. Prot., 33(04), 363–368. DOI: 10.2298/NTRP180316004V. VujčićI. MašićS. SpasevskaH. DramicaninM. 2018 Accuracy of determining absorbed irradiation dose at different temperature measurements using ethanol-chlorobenzene oscillotitrator system Nucl. Technol. Radiat. Prot. 33 04 363 368 10.2298/NTRP180316004V Open DOISearch in Google Scholar

European Directorate for the Quality of Medicines & HealthCare. (2011). European Pharmacopoeia 7.0. European Directorate for the Quality of Medicines & HealthCare 2011 European Pharmacopoeia 7.0. Search in Google Scholar

Büchi Labortechnik AG. (2007). Application Note. Hydrolysis Unit E-416, Extraction Unit E-816 Soxhlet. Fat determination according to Weibull-Stoldt – Standard application. Büchi Labortechnik AG 2007 Application Note. Hydrolysis Unit E-416, Extraction Unit E-816 Soxhlet. Fat determination according to Weibull-Stoldt – Standard application Search in Google Scholar

International Organization for Standardization. (2009). ISO 1871:2009 Food and feed products – General guidelines for the determination of nitrogen by the Kjeldahl method. International Organization for Standardization 2009 ISO 1871:2009 Food and feed products – General guidelines for the determination of nitrogen by the Kjeldahl method Search in Google Scholar

Kjeldahl, J. (1883). Neue Methode zur Bestimmung des Stickstoffs in organischen Körpern (New method for the determination of nitrogen in organic substances). Z. Anal. Chemie, 22(1), 366–383. KjeldahlJ. 1883 Neue Methode zur Bestimmung des Stickstoffs in organischen Körpern (New method for the determination of nitrogen in organic substances) Z. Anal. Chemie 22 1 366 383 10.1007/BF01338151 Search in Google Scholar

Masuko, T., Minami, A., Iwasaki, N., Majima, T., Nishimura, S., & Lee, Y. C. (2005). Carbohydrate analysis by a phenol-sulfuric acid method in microplate format. Anal. Biochem., 339(1), 69–72. MasukoT. MinamiA. IwasakiN. MajimaT. NishimuraS. LeeY. C. 2005 Carbohydrate analysis by a phenol-sulfuric acid method in microplate format Anal. Biochem. 339 1 69 72 10.1016/j.ab.2004.12.001 Search in Google Scholar

Maraei, R. W., & Elsawy, K. M. (2017). Chemical quality and nutrient composition of strawberry fruits treated by γ-irradiation. J. Radiat. Res. Appl. Sci., 10(1), 80–87. DOI: 10.1016/j.jrras.2016.12.004. MaraeiR. W. ElsawyK. M. 2017 Chemical quality and nutrient composition of strawberry fruits treated by γ-irradiation J. Radiat. Res. Appl. Sci. 10 1 80 87 10.1016/j.jrras.2016.12.004 Open DOISearch in Google Scholar

Onyenekwe, P. C., Ogbadu, G. H., & Hashimoto, S. (1997). The effect of gamma radiation on the microflora and essential oil of Ashanti pepper (Piper guineense) berries. Postharvest Biol. Technol., 10(2), 161–167. DOI: 10.1016/s0925-5214(96)01297-5. OnyenekweP. C. OgbaduG. H. HashimotoS. 1997 The effect of gamma radiation on the microflora and essential oil of Ashanti pepper (Piper guineense) berries Postharvest Biol. Technol. 10 2 161 167 10.1016/s0925-5214(96)01297-5 Open DOISearch in Google Scholar

Jan, K., Bashir, K., & Maurya, V. K. (2021). Gamma irradiation and food properties. In K. Knoerzer & K. Muthukumarappan (Eds.), Innovative food processing technologies: A comparative review (Vol. 3, pp. 41–60). Cambridge: Elsevier. DOI: 10.1016/B978-0-08-100596-5.23052-7. JanK. BashirK. MauryaV. K. 2021 Gamma irradiation and food properties In KnoerzerK. MuthukumarappanK. (Eds.), Innovative food processing technologies: A comparative review 3 41 60 Cambridge Elsevier 10.1016/B978-0-08-100596-5.23052-7 Open DOISearch in Google Scholar

World Health Organization. (1999). High-dose irradiation: Wholesomeness of food irradiated with doses above 10 kGy. Report of a Joint FAO/IAEA/WHO study group. Geneva: WHO. (Technical Report Series 890). World Health Organization 1999 High-dose irradiation: Wholesomeness of food irradiated with doses above 10 kGy. Report of a Joint FAO/IAEA/WHO study group Geneva WHO (Technical Report Series 890). Search in Google Scholar

Recommended articles from Trend MD

Plan your remote conference with Sciendo