Skip to main content
NCBI home page
Journal of Food Science and Technology logoLink to Journal of Food Science and Technology
. 2021 Apr 7;58(9):3579–3588. doi: 10.1007/s13197-021-05087-4

Effect of gamma radiation on microbial load, physico-chemical and sensory characteristics of common spices for storage

Mahfuzur Rahman 1,✉, M A Islam 4, Keshob C Das 3, Md Salimullah 3, M Z I Mollah 2, Ruhul A Khan 2
PMCID: PMC8292502  PMID: 34366475

Abstract

The effect of gamma radiation on the decontamination of microbial population, physico-chemical, radiation sensitivity and sensory characteristics of common spices for storage were evaluated. Spices were irradiated with gamma doses of 0 (as control), 2, 4, 6, 8 and 10 kGy, packed in the glass vials and stored at room temperature (22 ± 2°C) in the laboratory. In this research, Bacillus, Salmonella and Listeria species were identified in un-irradiated spice samples. Results also indicated that gamma radiation reduced the total microbial population compared to control and optimum gamma radiation doses (6 kGy for red chili and turmeric; 4 kGy for cumin, coriander, garlic and black pepper; 2 kGy for ginger powder samples) were identified for decontamination of the organisms in the studied spices. It was concluded that no significant differences before and after gamma radiation were observed in physico-chemical, nutritional and sensory properties but significantly changed in microbial load in spices samples.

Keywords: Spices, Gamma radiation, Decontamination, Physico-chemical, Sensory characteristics

Introduction

Spices are usually used as a major component of cooking to create taste, color, flavor and improved nutrient values in food items and it has also antioxidant and antimicrobial properties. Spices are a vital source of a micronutrient that is useful for adults and child’s body growth and development (Rahman et al. 2018). But several studies reported that spices are contaminated by foodborne bacteria due to various reasons such as improper harvesting, processing, transportation and storage (Mandel 2005). Additionally, the attendance of foodborne bacteria like Salmonella, E. coli, Listeria, Pseudomonas, Clostridium perfringens, Staphylococcus aureus and Bacillus cereus species were found in spice powder (Jamali et al. 2013). In the past, conventional thermal treatment was used for sterilization purposes worldwide even many countries have used this process till now. It is also reported that this sterilization may induce adverse effects in physico-chemical properties mainly color, flavor and texture in food items (Zhang and Tan 2021). By this process, food products are not fully sterile against foodborne microorganisms due to a lack of proper heat transfer to the products (Zhang et al. 2020). On the other hand, food irradiation is a process exposing food to ionizing radiation such as gamma rays emitted from the radioisotope 60Co produced by machine sources. Gamma irradiation (60Co) techniques are an effective method to completely kill foodborne bacteria without changes physico-chemical and sensory properties (Umesha and Manukumar 2018). Gamma irradiation is an effective method to damage DNA of organisms as a result organisms cannot grow and multiply in the food items. The Joint FAO/IAEA/WHO Expert Committee reported that irradiation up to 10 kGy does not produce toxicological risks and nutritional problems in foodstuffs (Ravindran & Jaiswal 2019). This technique will reduce the post-harvest loss, extend shelf-life and improved food safety without changing quality.

Commercial application of gamma irradiation is increased in recent years even the USA also actively encourages to use of this technology. Commercial food irradiation technology has been recently started in Brazil, China, India, the Republic of Korea, Mexico and Thailand. In Europe, some countries were early supporters of industrial food irradiation, particularly the Netherlands and France (Galati et al. 2019). Bangladesh has started to treat gamma irradiation of foodstuffs commercially and exported to different countries of the world. It is very important to ensure the toxicity and quality of the product after gamma irradiation. Therefore, the objective of this study was to investigate the optimum gamma irradiation dose to decontaminate the food-borne organisms in spices. The effects of the gamma radiation in physico-chemical, radiation sensitivity and sensory characteristics were also studied. The study also provided effective information for good storage practices after irradiation to avoid bacterial contaminations in spices powder.

Materials and methods

Preparation of samples

Seven types of spice samples in powder form were randomly collected from local markets of Dhaka, Bangladesh in March 2018. The samples are red chili (Capsicum annuum), turmeric (Curcuma longa), coriander (Coriandrumsativum), cumin (Cuminum cyminum), black pepper (Piper nigrum), garlic (Allium sativum), and ginger (Zingiber officinale). Samples were kept at room temperature until analysis. About 20 gm of each spice sample was packed in the glass vials and divided into 6 groups. One group of each sample was not exposed to gamma-ray and kept as control and the rest of the 5 groups were exposed to 2, 4, 6, 8 and 10 kGy.

Irradiation of samples and dosimetry

The experiment was done in the Institute of Food and Radiation Biology (IFRB), Atomic Energy Research Establishment, Saver, Dhaka, Bangladesh. Samples were irradiated using a gamma irradiator with a Cobalt-60 source (Gamma beam 650, AECL, Canada). The activity of gamma irradiator was 50 kCi that was used for spices irradiation. The absorbed dose was measured using ferrous sulfate (Fricke) and red perspex dosemeters. Red perspex dosemeters (Type 4034 AF, AERE, Harwell, UK, and dose range 5–50 kGy) were standardized against Fricke dosimeters.

Analysis of microbial loads

All samples were analyzed for the total bacterial count (TBC) by a standard plate count method. Five grams of each spice powder was mixed with 45 ml sterilized water. Subsequent dilutions were prepared and plated on plate count agar for determining the bacterial count. Microbial counting was performed 24–48 h after incubation at 37°C for TBC (Alam et al. 1992).

Bacteria identify in the spices samples

About 5 g samples dissolved in about 45 ml of autoclaved distilled water and incubated at 37 °C for 24–48 h. About 5 ml of the incubated this culture was selectively enriched into the HiCrome Bacillus agar (Hi Media), and incubated again at 37 °C for overnight. Then the presumptive colonies of Bacillus spp. were sub-cultured onto nutrient media to get pure culture. The isolates were identified as Bacillus spp. Based on Gram staining, colony morphology on HiCrome Bacillus agar, SS agar biochemical characterization of the isolates (amylase, lipase, protease, glucose, lactose, mannitol, galactose, oxidase, citrate, indole, catalase and VP) followed by standard procedure Bhattacharya et al. 2020. Five selective media xylose lysine deoxycholate agar/XLD (liofilchem, Italy), pseudomonas selective agar (liofilchem, Italy), listeria selective agar (Oxoid, Basingstoke, UK), Thiosulfate-citrate-bile salts-sucrose agar/TCBS (liofilchem, Italy), and Eosin methylene blue agar/EMB (Oxoid, Basingstoke, UK) were used to determine the attendance of selective types organisms at 37°C for 24–48 h (Jamali et al. 2013).

Calculation of the radiation D-values

D10 values of spices were calculated according to Kim et al. (2018) for 0 and 6 months of storage samples. The microbial reduction ratio (N/N0) was found by dividing the average number of remaining organism’s cfu/gm (N) in the irradiated and the average number of organisms in the un-irradiated samples (N0). The log reduction (log [N/N0]) of the organisms after irradiation treatment was plotted against the radiation dose. The D10 values were considered as the reciprocals of the slopes of the linear regression models of the reduction ratio.

Sensory evaluation

Sensory evaluation was done by panelists on the 180th day of storage. Irradiated spice samples were used to prepare ready-to-eat food. All samples were presented randomly to the panelists and evaluated under ordinary light conditions. Ten members were checked and evaluated based on color, texture and flavor/odor. The evaluations were done by a hedonic scale of nine points (9 = like extremely to 1 = dislike extremely), according to Roy et al. (2018).

Physicochemical properties of spices

Moisture

Spice powder was mixed properly to determine the moisture content of the samples. 1gm of the sample was heated at 105 °C for 2 h by automatic moisture analyzer Kern and Sohn GmbH, D-72336, Germany (AOAC 2005).

pH

To determine the pH values, spices: distilled water = 1:9 suspensions for each sample were prepared and stirred for 2 h in 200 ml beaker (Waje et al. 2008). The pH of the suspension was measured using edge® digital pH meter.

Nutritional properties

Protein, fat and ash content were determined using official methods (AOAC 2005).

Statistical analyses

All analyses were done at least three times. Results were expressed as mean values with standard deviation. Statistical analysis was performed using the Statistical Software R (windows version 3.3.2). Duncan test was performed to evaluate the significance of the difference between mean values at the level of p ≤ 0.05.

Results and discussion

Effect of gamma irradiation on microbial load of spices

The total microbial loads determined for irradiated and un-irradiated spice powder samples are presented in Table 1. In this study, total aerobic bacteria in un-irradiated spice samples were found in the range of 1.37 × 103 to 2.46 × 105 cfu/gm. The maximum level of contamination was found in red chili and the minimum was found in ginger powder (Table 1). All samples were stored at room temperature (about 22 ± 2°C) and continuously monitored. The presence of bacterial load was detected in red chili powder 2.46 × 105 cfu/gm; after 6 months bacterial load was found 2.9 5 × 105 cfu/gm. Similarly, the rate of contamination was increased rapidly for all un-irradiated spices during storage. Thus, proper irradiation treatment was needed to reduce bacterial contamination in the samples. In this study, the levels of bacterial contamination were reduced by 2 and 4 kGy gamma doses, but no contamination was found in the samples treated to 6, 8 and 10 kGy. The acceptable limit of microorganisms was set by codex Alimentarius in spices below 103–104 cfu/gm (Codex Alimentarius Commission 1990). The levels of contamination by organisms in red chili, turmeric, cumin, garlic and black pepper powder were exceeded the safe level compared to the codex report. The limit of total coliforms is considered satisfactory for < 104 and unsatisfactory for ≥ 104 according to ICMSF 1974.

Table 1.

Microbial means for control (0 kGy) and irradiated (2, 4, 6 kGy) in spices powder during room temperature storage

Gamma dose (kGy) Days Red chili Turmeric Cumin Coriander Garlic Ginger Black pepper
0 0 2.46 × 105 1.62 × 105 1.54 × 104 4.75 × 103 3.09 × 104 1.37 × 103 3.59 × 104
180 2.95 × 105 2.38 × 105 2.38 × 104 5.18 × 103 4.72 × 104 4.07 × 103 4.05 × 104
2 0 4.47 × 103 1.37 × 103 9.53 × 102 2.65 × 102 2.45 × 102 ND 2.55 × 102
180 3.73 × 102 6.16 × 102 5.06 × 102 2.05 × 102 1.25 × 102 ND 2.05 × 102
4 0 6.25 × 102 4.23 × 102 ND ND ND – ND
180 5.00 × 102 2.30 × 102 ND ND ND – ND
6 0 – – – – – – –
180 – – – – – – –
Open in a new tab

ND = Not detectable (the minimum detection level as 10 CFU/g)

Values are means of triplicate experiments (n = 3)

Dash (-) = Absence of microorganisms (no microbial colonies)

Physico-chemical properties of un-irradiated and irradiated spices

The determined properties (moisture, fat, protein, ash and pH) in spices samples during storage are presented in Table 2. The maximum moisture content in cumin (7.74%) and minimum in red chili (5.84%) were found among the seven types of un-irradiated spices. In this investigation, irradiated spices presented lower moisture content compared with that of the un-irradiated samples. The amount of moisture content was a little increased in un-irradiated samples; on the other hand, storage for 6 months moisture content was decreased in irradiated samples. For un-irradiated samples, air moisture was initially absorbed, so moisture content was a little increased. As radiation is known to induce depolymerization of polysaccharides and this radiation-induced damage causes considerable changes in the cell membranes and connective tissues leading to softening and easier water release in samples. Therefore, for irradiated samples, moisture content was increased initially, but since equilibrium condition was maintained the moisture content of irradiated spices was decreased for 6 months of storage. From the literature study, similar results were reported for black pepper powder by Waje et al. 2008. Other properties of the spice samples like contents of fat (%), protein (%) and ash (%) were found in un-irradiated samples ranged from 1.27–9.04, 2.79–10.20 and 7.03- 11.10, respectively for 0 month storage time and 1.19–8.94, 2.70–10.03 and 6.99–10.90, respectively for 6 months storage. The result indicated that fat, protein and ash contents were gradually reduced in the un-irradiated and irradiated samples. Similar observations were found in red ginseng powder by Siddhuraju et al. (2002). Another study reported that the moisture (%), ash (%), protein (%) and fat (%) contents were found in turmeric samples as 8.92, 2.85, 9.40 and 6.85, respectively (Ikpeama et al. 2014). The previous study also reported that moisture content (%) and pH were found 13.76 and 4.7 in red chili, 9.89 and 6.1 in black pepper, 12.70 and 6.6 in turmeric, 13.0 and 7.1 in ginger (Mandel 2005). Fat and protein are important components of the body; protein provides amino acids and vital nitrogen for humans for body growth and development (Guo et al. 2017). This study reveals that the percentage of fat and protein was not affected by low gamma doses in spices. The pH values were also determined before and after gamma irradiation of the spice samples. The pH values were found in un-irradiated and irradiated samples range 5.71–6.47 for 0 month storage; 5.64–6.44 for 6 months storage period. The maximum and minimum pH values were found in coriander and red chili powder respectively. In this investigation pH value slightly decreases after storage in control and irradiated samples because of the increased amount of organic acids released during gamma irradiation. Overall, this study provides information before and after the treatment of gamma irradiation with different doses in spices (0, 2, 4 and 6 kGy). After low irradiation gamma doses up to 6 kGy, there are no significant changes in physico-chemical and nutritional properties in the samples. Other properties like color, flavor, aroma, phenolic and sensory properties do not change after treated low irradiation gamma doses (< 10 kGy) were also found in the previous studies (Aylangan et al. 2017).

Table 2.

Physico-chemical and nutritional properties of spices (red chili, turmeric, cumin and coriander powder) during storage

Gamma dose (kGy) Parameters Red chili Turmeric Cumin Coriander
0 month 6 months 0 month 6 months 0 month 6 months 0 month 6 months
0 Moisture (%) 5.84 ± 0.03a 6.05 ± 0.02a 7.73 ± 0.02a 7.93 ± 0.03a 7.74 ± 0.04a 7.86 ± 0.02a 5.75 ± 0.03a 5.85 ± 0.03a
Fat (%) 6.52 ± 0.03a 6.47 ± 0.02a 9.04 ± 0.05a 8.94 ± 0.03a 5.05 ± 0.05a 4.95 ± 0.11a 1.27 ± 0.12a 1.19 ± 0.03a
Protein (%) 10.2 ± 0.3a 10.0 ± 0.2a 6.62 ± 0.03a 6.55 ± 0.07a 9.62 ± 0.03a 9.49 ± 0.08a 3.71 ± 0.15a 3.63 ± 0.07a
Ash (%) 10.1 ± 0.1a 9.97 ± 0.25a 11.1 ± 0.1a 10.9 ± 0.3a 9.05 ± 0.14a 9.03 ± 0.21a 10.1 ± 0.1a 9.93 ± 0.38a
pH 5.71 ± 0.02a 5.64 ± 0.02a 6.36 ± 0.01a 6.27 ± 0.02a 5.81 ± 0.01a 5.72 ± 0.11a 6.47 ± 0.03a 6.44 ± 0.04a
2 Moisture (%) 5.81 ± 0.01a 5.80 ± 0.03b 7.68 ± 0.03b 7.66 ± 0.02bc 7.77 ± 0.05a 7.73 ± 0.02bc 5.64 ± 0.03c 5.64 ± 0.03c
Fat (%) 6.50 ± 0.02a 6.43 ± 0.05ab 9.08 ± 0.02a 8.81 ± 0.22ab 4.98 ± 0.09a 4.86 ± 0.06a 1.13 ± 0.06a 1.20 ± 0.01a
Protein (%) 10.1 ± 0.6a 10.0 ± 0.6a 6.63 ± 0.07a 6.52 ± 0.03a 9.56 ± 0.05a 9.55 ± 0.05a 3.85 ± 0.05a 3.64 ± 0.14a
Ash (%) 10.2 ± 0.2a 9.90 ± 0.05a 11.2 ± 0.2a 10.8 ± 0.2a 9.09 ± 0.09a 9.05 ± 0.13a 10.1 ± 0.1a 9.97 ± 0.15a
pH 5.62 ± 0.02b 5.61 ± 0.02a 6.26 ± 0.01b 6.23 ± 0.04a 5.72 ± 0.03b 5.68 ± 0.02ab 6.42 ± 0.03ab 6.40 ± 0.02ab
4 Moisture (%) 5.84 ± 0.02a 5.81 ± 0.01b 7.69 ± 0.01ab 7.62 ± 0.01c 7.75 ± 0.03a 7.69 ± 0.04c 5.70 ± 0.02b 5.64 ± 0.03c
Fat (%) 6.52 ± 0.03a 6.43 ± 0.06ab 9.08 ± 0.03a 8.80 ± 0.03ab 5.08 ± 0.03a 4.90 ± 0.10a 1.20 ± 0.05a 1.09 ± 0.01b
Protein (%) 10.2 ± 0.1a 9.97 ± 0.16a 6.70 ± 0.10a 6.51 ± 0.10a 9.51 ± 0.12a 9.49 ± 0.05a 3.84 ± 0.04a 3.64 ± 0.10a
Ash (%) 10.1 ± 0.2a 9.86 ± 0.15a 11.0 ± 0.1a 10.6 ± 0.4a 9.03 ± 0.55a 9.09 ± 0.44a 10.2 ± 0.2a 9.80 ± 0.20a
pH 5.53 ± 0.07c 5.51 ± 0.04b 6.20 ± 0.02c 6.17 ± 0.02b 5.63 ± 0.02c 5.61 ± 0.06ab 6.33 ± 0.11bc 6.36 ± 0.02b
6 Moisture (%) 5.76 ± 0.04b 5.78 ± 0.04b 7.68 ± 0.03b 7.69 ± 0.04b 7.73 ± 0.06a 7.75 ± 0.03b 5.68 ± 0.01bc 5.71 ± 0.02b
Fat (%) 6.35 ± 0.07b 6.34 ± 0.08b 8.95 ± 0.15a 8.71 ± 0.06b 4.99 ± 0.11a 4.83 ± 0.16a 1.12 ± 0.09a 1.07 ± 0.05b
Protein (%) 10.2 ± 0.3a 10.0 ± 0.4a 6.64 ± 0.07a 6.51 ± 0.04a 9.56 ± 0.05a 9.46 ± 0.11a 3.82 ± 0.06a 3.68 ± 0.04a
Ash (%) 10.1 ± 0.1a 9.97 ± 0.15a 10.1 ± 0.1a 10.8 ± 0.2a 9.07 ± 0.03a 9.04 ± 0.15a 10.2 ± 0.06a 9.67 ± 0.29a
pH 5.52 ± 0.02c 6.50 ± 0.03b 6.19 ± 0.01c 6.16 ± 0.01b 5.61 ± 0.02c 5.57 ± 0.02b 6.26 ± 0.04c 6.27 ± 0.06c
Gamma dose (kGy) Parameters Garlic Ginger Black pepper
0 month 6 months 0 month 6 months 0 month 6 months
0 Moisture (%) 7.21 ± 0.02a 7.44 ± 0.03a 6.85 ± 0.03a 6.90 ± 0.02a 7.59 ± 0.09a 7.67 ± 0.03a
Fat (%) 4.21 ± 0.03c 4.18 ± 0.03b 2.21 ± 0.05a 2.20 ± 0.02a 2.49 ± 0.04a 2.40 ± 0.03a
Protein (%) 3.0 ± 0.07b 2.94 ± 0.11b 2.79 ± 0.06b 2.70 ± 0.11b 3.20 ± 0.02a 3.16 ± 0.05a
Ash (%) 7.03 ± 0.12a 6.99 ± 0.20a 9.34 ± 0.66a 9.04 ± 0.90a 9.41 ± 0.36a 9.38 ± 0.33a
pH 5.86 ± 0.05a 5.83 ± 0.04a 5.93 ± 0.04a 5.85 ± 0.04a 5.88 ± 0.05a 5.81 ± 0.01a
2 Moisture (%) 7.25 ± 0.03a 7.24 ± 0.03b 6.84 ± 0.02a 6.82 ± 0.02b 7.55 ± 0.04a 7.57 ± 0.03b
Fat (%) 4.27 ± 0.02b 4.18 ± 0.03a 2.26 ± 0.03a 2.18 ± 0.03a 2.56 ± 0.04a 2.43 ± 0.07a
Protein (%) 3.10 ± 0.02a 2.92 ± 0.14a 2.89 ± 0.06a 2.87 ± 0.03a 3.20 ± 0.02a 3.14 ± 0.04a
Ash (%) 6.97 ± 0.16a 6.89 ± 0.34a 9.37 ± 0.32a 9.13 ± 0.15a 9.34 ± 0.18a 9.39 ± 0.10a
pH 5.83 ± 0.02ab 5.80 ± 0.03ab 5.90 ± 0.02a 5.89 ± 0.01a 5.84 ± 0.04ab 5.77 ± 0.03b
4 Moisture (%) 7.25 ± 0.03a 7.26 ± 0.02b 6.84 ± 0.01a 6.78 ± 0.01c 7.58 ± 0.02a 7.55 ± 0.03b
Fat (%) 4.32 ± 0.03a 4.22 ± 0.02b 2.24 ± 0.04a 2.19 ± 0.03a 2.52 ± 0.04a 2.41 ± 0.07a
Protein (%) 3.0 ± 0.05b 2.88 ± 0.17b 2.87 ± 0.03ab 2.81 ± 0.10ab 3.17 ± 0.05a 3.13 ± 0.02a
Ash (%) 6.94 ± 0.33a 6.92 ± 0.10a 9.28 ± 0.38a 9.11 ± 0.48a 9.14 ± 0.31a 9.28 ± 0.15a
pH 5.81 ± 0.01ab 5.73 ± 0.02ab 5.82 ± 0.01b 5.79 ± 0.03b 5.81 ± 0.02ab 5.71 ± 0.01c
6 Moisture (%) 7.21 ± 0.02a 7.23 ± 0.02b 6.89 ± 0.04a 6.83 ± 0.03bc 7.55 ± 0.04a 7.62 ± 0.02a
Fat (%) 4.25 ± 0.02bc 4.20 ± 0.03b 2.23 ± 0.02a 2.17 ± 0.01a 2.32 ± 0.11b 2.25 ± 0.05b
Protein (%) 3.10 ± 0.02a 2.87 ± 0.20a 2.85 ± 0.03ab 2.88 ± 0.06a 3.16 ± 0.05a 3.13 ± 0.03a
Ash (%) 6.99 ± 0.17a 6.93 ± 0.28a 9.25 ± 0.27a 9.06 ± 0.06a 9.12 ± 0.11a 9.20 ± 0.06a
pH 5.78 ± 0.02b 5.70 ± 0.02b 5.81 ± 0.01b 5.76 ± 0.01b 5.80 ± 0.03b 5.65 ± 0.01d
Open in a new tab

a−cMean ± SD (n = 3), mean values with same row with different lower case letter are significantly different at p ≤ 0.05 among the gamma radiation dose

Radiation D10 values of organisms in spices samples

Spices were contaminated with various organisms; therefore D10 or 5D values determination is very much effective for decontamination of organisms. In this study, both the radiation sensitivity values of spice samples were presented in Table 3. The R2 values from the obtained regression equations (Fig. 1) ranged from 0.61 to 1.0 for 0 month storage samples. Similarly, The R2 values from the obtained regression equations (Fig. 1) ranged from 0.71 to 1.0 for 6 months storage samples. The D10 and 5D values of six spices 0 month stored samples were found in red chili 1.54 and 7.70 kGy; turmeric 1.55 and 7.75 kGy; cumin 1.66 and 8.30 kGy; coriander 1.60 and 8.0 kGy; garlic 0.95 and 4.75 kGy; black pepper 0.93 and 4.65 kGy, respectively. In this investigation, the maximum gamma dose (kGy) was calculated in cumin and the minimum in black pepper powder. Similarly, The D10 and 5D values of six spices 6 months stored samples were found in red chili 1.44 and 7.20 kGy; turmeric 1.42 and 7.10 kGy; cumin 1.20 and 6.0 kGy; coriander 1.42 and 7.10 kGy; garlic 0.78 and 3.90 kGy; black pepper 0.87 and 4.35 kGy, respectively. It is observed that the maximum gamma dose (kGy) was calculated in cumin and the minimum in black pepper powder. When ionizing radiation passes through food items, its energy is absorbed and absorbed energy leads to interactions between atoms and molecules, which outcomes in the inactivation of microorganisms (Rico et al. 2010). From the previous study, D10 value for gamma dose was calculated as 2.66 kGy in red pepper (Jung et al. 2015) that is two times higher than the value obtained in this study. Another study also reported that D10 values were found for black pepper 1.8 kGy, curry 2.1 kGy, cumin 0.46 kGy (Grecz et al. 1986).

Table 3.

Radiation D10 values (kGy) of total aerobic bacteria in spices powder

Gamma dose (kGy) Red chili Turmeric Cumin Coriander Garlic Black pepper
0 m 6 m 0 m 6 m 0 m 6 m 0 m 6 m 0 m 6 m 0 m 6 m
D10 value 1.54 ± 0.04 1.44 ± 0.03 1.55 ± 0.03 1.42 ± 0.02 1.66 ± 0.01 1.20 ± 0.01 1.60 ± 0.01 1.42 ± 0.01 0.95 ± 0.01 0.78 ± 0.01 0.93 ± 0.03 0.87 ± 0.02
5D value 7.70 ± 0.20 7.20 ± 0.15 7.75 ± 0.15 7.10 ± 0.10 8.30 ± 0.05 6.00 ± 0.05 8.00 ± 0.05 7.10 ± 0.05 4.75 ± 0.05 3.90 ± 0.05 4.65 ± 0.15 4.35 ± 0.10
Open in a new tab

D10 value of ginger cannot be calculated because bacterial colonies were not detectable at even 2 kGy

Fig. 1.

Fig. 1

Open in a new tab

Reduction of total aerobic bacteria in 0 and 6 months stored spices by gamma radiation

Prevalence of organisms in un-irradiated and irradiated spices

The presence of foodborne microorganisms in spices of un-irradiated and irradiated with different doses are given in Table 4. In this investigation, selective media were used for identifying the selective type of organism presence or not in the samples. Likewise, Bacillus spp. was detected in all spices powder but Salmonella spp. was detected in only red chili powder. Listeria spp. was found in red chili, turmeric and black pepper powder. This study also investigated, Pseudomonas, E. coli and Vibrio spp. were not detected in spice samples. From previous studies, Bacillus spp. (Mathot et al. 2021), Salmonella spp. (Lins 2018), Listeria spp. (Zec and Glibetic 2020), E. coli spp. (Amrutha et al. 2017) and Clostridium spp. (Li et al. 2020) were found in spices in this type of researches. For these reasons, gamma irradiation is an effective method to reduce the level of contamination in spice samples. It is also effective to reduce the growth of foodborne organisms in the samples (Robichaud et al. 2020; Maherani et al. 2019). In this study, the optimum doses (2 kGy = ginger; 4 kGy = cumin, coriander, garlic and black pepper; 6 kGy = red chili and turmeric) were identified for the spice samples. Similar observations were found in spices during 6 months storage period. From literature studies, 0.8–4.0 kGy are extremely effective in reducing Salmonella spp. (Osaili et al. 2018), 3.0 kGy is also effective in reducing Listeria spp. (Lucas et al. 2021). The previous studies reported a dose of 6 kGy reduced the total aerobic microbial contamination in red pepper effectively without changes in major quality in foodstuffs (Jung et al. 2015; Song et al. 2014). Another study also reported that 10 kGy was used for decontamination in dried red pepper and black pepper (Waje et al. 2008; Rico et al. 2010); an overall dose of 10 kGy is accepted in many countries (Woldemariam et al. 2021). A previous study in Bangladesh reported that 10 kGy was used for total bacterial count below the detectable limit and coliforms were eliminated by 5 kGy in red chili, turmeric, coriander and cumin powder (Alam et al. 1992).

Table 4.

Presence of foodborne microorganisms in control and irradiated samples for 6 months storage

Spices Gamma dose (kGy) Bacillus spp. Salmonella spp. Pseudomonas spp. Listeria spp. E. coli spp. Vibrio spp.
0 m 6 m 0 m 6 m 0 m 6 m 0 m 6 m 0 m 6 m 0 m 6 m
Red chili 0 ++ ++ ++ ++ –– –– ++ ++ –– –– –– ––
2 ++ ++ ++ ++ –– –– ++ ++ –– –– –– ––
4 ++ ++ –– –– –– –– ++ ++ –– –– –– ––
6 –– –– –– –– –– –– –– –– –– –– –– ––
Turmeric 0 ++ ++ –– –– –– –– ++ ++ –– –– –– ––
2 ++ ++ –– –– –– –– ++ ++ –– –– –– ––
4 ++ ++ –– –– –– –– ++ ++ –– –– –– ––
6 –– –– –– –– –– –– –– –– –– –– –– ––
Cumin 0 ++ ++ –– –– –– –– –– –– –– –– –– ––
2 ++ ++ –– –– –– –– –– –– –– –– –– ––
4 –– –– –– –– –– –– –– –– –– –– –– ––
6 –– –– –– –– –– –– –– –– –– –– –– ––
Coriander 0 ++ ++ –– –– –– –– –– –– –– –– –– ––
2 ++ ++ –– –– –– –– –– –– –– –– –– ––
4 –– –– –– –– –– –– –– –– –– –– –– ––
6 –– –– –– –– –– –– –– –– –– –– –– ––
Garlic 0 ++ ++ –– –– –– –– –– –– –– –– –– ––
2 ++ ++ –– –– –– –– –– –– –– –– –– ––
4 –– –– –– –– –– –– –– –– –– –– –– ––
6 –– –– –– –– –– –– –– –– –– –– –– ––
Ginger 0 ++ ++ –– –– –– –– –– –– –– –– –– ––
2 –– –– –– –– –– –– –– –– –– –– –– ––
4 –– –– –– –– –– –– –– –– –– –– –– ––
6 –– –– –– –– –– –– –– –– –– –– –– ––
Black pepper 0 ++ ++ –– –– –– –– ++ ++ –– –– –– ––
2  +  +   +  +  –– –– –– –– ++ ++ –– –– –– ––
4 –– –– –– –– –– –– –– –– –– –– –– ––
6 –– –– –– –– –– –– –– –– –– –– –– ––
Open in a new tab

Each + or – symbols represent respectively, presence or Absence of the microorganisms in one of duplicate plates

Sensory evaluations

Sensory evaluations by panelists in 7 types of irradiated and un-irradiated spices samples are given in Table 5. The sensory properties of spices were evaluated in terms of color, texture and flavor/odor within 6 months of storage period. In this study, the optimum dose was calculated for spice samples so that, the sensory evaluation was compared with irradiated spices and un-irradiated spice samples. The maximum and minimum score of un-irradiated samples are 7.25 and 6.70; and for irradiated samples are 7.85 and 6.60, respectively (Table 3). According to panelists, evaluation scores for both irradiated and non-irradiated samples indicate that all were highly acceptable during the storage period. The previous studies reported that low doses of gamma irradiation treatment do not change properties in spice samples (Rico et al. 2010; Waje et al. 2008). In this study, the sensory evaluation scores were not significantly different for irradiated and un-irradiated spice samples during storage.

Table 5.

Sensory properties evaluation scores of irradiated and un-irradiated spices with stored for180 days

Gamma dose (kGy) Sensory parameters Days Red chili Turmeric Cumin Coriander Garlic Ginger Black pepper
0 Color 180 7.15 ± 0.55a 7.10 ± 0.61a 7.00 ± 0.41a 7.05 ± 0.55a 7.05 ± 0.55a 6.85 ± 0.53a 6.95 ± 0.44a
Texture 180 7.08 ± 0.50a 7.10 ± 0.46a 7.05 ± 0.50a 7.15 ± 0.67a 6.90 ± 0.52a 6.85 ± 0.63a 7.15 ± 0.41a
Flavor/odor 180 7.25 ± 0.51a 7.05 ± 0.37a 6.90 ± 0.46a 7.10 ± 0.61a 6.85 ± 0.82a 6.70 ± 0.67a 6.90 ± 0.66a
2 Color 180 6.95 ± 0.42a 6.95 ± 0.44a 6.90 ± 0.52a 6.80 ± 0.59a 6.80 ± 0.67a 6.75 ± 0.75a 6.75 ± 0.35a
Texture 180 6.88 ± 0.38a 7.05 ± 0.44a 6.95 ± 0.37a 6.90 ± 0.39a 6.85 ± 0.53a 6.75 ± 0.75a 6.85 ± 0.63a
Flavor/odor 180 6.95 ± 0.47ab 6.90 ± 0.39a 6.90 ± 0.52a 6.80 ± 0.59a 6.85 ± 0.63a 6.80 ± 0.67a 6.60 ± 0.66a
4 Color 180 6.85 ± 0.50a 6.85 ± 0.41a 6.85 ± 0.41a 6.75 ± 0.35a 6.75 ± 0.35a 6.70 ± 0.59a 6.75 ± 0.35a
Texture 180 6.90 ± 0.44a 6.80 ± 0.35a 6.85 ± 0.63a 6.95 ± 0.55a 6.70 ± 0.54a 6.75 ± 0.35a 6.70 ± 0.67a
Flavor/odor 180 6.90 ± 0.30ab 6.85 ± 0.41a 6.85 ± 0.41a 6.85 ± 0.47a 6.75 ± 0.35a 6.65 ± 0.58a 6.75 ± 0.49a
6 Color 180 6.80 ± 0.60a 6.90 ± 0.57a 6.80 ± 0.48a 6.90 ± 0.46a 6.95 ± 0.44a 6.85 ± 0.41a 6.65 ± 0.58a
Texture 180 6.90 ± 0.44a 6.95 ± 0.44a 6.90 ± 0.39a 6.85 ± 0.47a 6.85 ± 0.41a 6.90 ± 0.57a 6.80 ± 0.63a
Flavor/odor 180 6.75 ± 0.34a 6.95 ± 0.44a 6.80 ± 0.42a 6.95 ± 0.50a 6.75 ± 0.63a 6.70 ± 0.59a 6.65 ± 0.58a
Open in a new tab

Sensory evaluation was conducted by 10 panelists using a 7-point hedonic scale (7 = very good, 1 = very bad)

a,bMean ± SD (n = 3), mean values with same row with different lower case letter are significantly different at p ≤ 0.05 among the gamma radiation dose

Conclusion

Application of gamma radiation may be effective to reduce microbial load and extend shelf life without changing physico-chemical properties of spices samples. In this study, the optimum gamma doses were identified as 6 kGy for red chili and turmeric; 4 kGy for cumin, coriander, garlic and black pepper; 2 kGy for ginger powder. Bacillus, Salmonella and Listeria species were completely removed low radiation gamma doses (< 10 kGy) in spices samples. The results of this study also contribute to promoting the application of gamma irradiation in the commercial production of spice powder.

Acknowledgments

The authors thank the authority of the National Institute of Biotechnology (NIB) and Atomic Energy Research Establishment (AERE), Savar, Dhaka, Bangladesh for providing laboratory facilities.

Authors' contributions

MR: Experimental work, manuscript prepares and corrections according to expert comments were done. MAI: Revision, reshaping of the manuscript. KCD: Important guidelines during the experiment were done. MS: Revising and critical feedback. MZIM: Revising and critical feedback. RAK: Planning, writing the draft and overall supervision.

Funding

None.

Compliance with ethical standard

Conflicts of interest

The authors declare that they have no conflict of interest.

Consent for publication

Appropriate attributions were made for images where applicable.

Footnotes

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

References

  1. Alam MK, Choudhury N, Chowdhury NA, Youssouf QM. Decontamination of spices by gamma radiation. Lett Appl Microbiol. 1992;14:199–202. [Google Scholar]
  2. Amrutha B, Sundar K, Shetty PH. Spice oil nanoemulsions: potential natural inhibitors against pathogenic E. coli and Salmonella spp. from fresh fruits and vegetables. LWT Food Sci Technol. 2017;79:152–159. doi: 10.1007/s13197-017-2555-2. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. AOAC . Determination of moisture, ash, protein and fat. Official method of analysis of the association of analytical chemists. 18. Washington DC: AOAC; 2005. [Google Scholar]
  4. Aylangan A, Ic E, Ozyardimci B. Investigation of gamma irradiation and storage period effects on the nutritional and sensory quality of chickpeas, kidney beans and green lentils. Food Control. 2017;80:428–434. [Google Scholar]
  5. Bhattacharya D, de los Santos Villalobos S, Ruiz VV, Selvin J, Mukherjee J. Bacillus rugosus sp. nov. producer of a diketopiperazine antimicrobial, isolated from marine sponge Spongia officinalis L. Antonie Van Leeuwenhoek. 2020;113:1675–1687. doi: 10.1007/s10482-020-01472-9. [DOI] [PubMed] [Google Scholar]
  6. Codex Alimentarius Commission (1990) Report of the fifteenth session of the codex committee on processed meat and poultry products. Joint FAO/WHO Food Standards Programme Codex Alimentarius Commission, Copenhagen, Denmark
  7. Galati A, Tulone A, Moavero P, Crescimanno M. Consumer interest in information regarding novel food technologies in Italy: the case of irradiated foods. Food Res Int. 2019;119:291–296. doi: 10.1016/j.foodres.2019.01.065. [DOI] [PubMed] [Google Scholar]
  8. Grecz N, Al-Harithy R, Jaw R. Radiation sterilization of spices for hospital food services and patient care. J Food Saf. 1986;7:241–255. [Google Scholar]
  9. Guo Q, Ye A, Bellissimo N, Singh H, Rousseau D. Modulating fat digestion through food structure design. Prog Lipid Res. 2017;68:109–118. doi: 10.1016/j.plipres.2017.10.001. [DOI] [PubMed] [Google Scholar]
  10. ICMSF . Micro-organisms in foods 2: sampling for microbiological analysis: principles and specific applications. Toronto, Canada: Blackwell Scientific Publications; 1974. [DOI] [PubMed] [Google Scholar]
  11. Ikpeama A, Onwuka GI, Nwankwo C. Nutritional composition of tumeric (Curcuma longa) and its antimicrobial properties. Int J Sci Eng Res. 2014;5:1085–1089. [Google Scholar]
  12. Jamali H, Chai LC, Thong KL. Detection and isolation of Listeria spp. and Listeria monocytogenes in ready-to-eat foods with various selective culture media. Food Control. 2013;32:19–24. [Google Scholar]
  13. Jung K, Song BS, Kim MJ, Moon BG, Go SM, Kim JK, Park JH. Effect of X-ray, gamma-ray, and electron beam irradiation on the hygienic and physicohemical qualities of red pepper powder. LWT Food Sci Technol. 2015;63:846–851. [Google Scholar]
  14. Kim GR, Ramakrishnan SR, Kwon JH. Radiosensitivity of microorganisms in Saengshik products and irradiation effects on the sensorial properties. Radiat Phys Chem. 2018;152:100–106. [Google Scholar]
  15. Li Y, Zhang Y, Zhang L, Hu Y, Hong C, Xie A, Mei L. Prevalence and genetic characteristics of Cronobacter spp. from food and human clinical stool samples in Wenzhou, China 2008–2018. Food Microbiol. 2020;89:103432. doi: 10.1016/j.fm.2020.103432. [DOI] [PubMed] [Google Scholar]
  16. Lins P. Detection of Salmonella spp. in spices and herbs. Food Control. 2018;83:61–68. [Google Scholar]
  17. Lucas JR, Alía A, Velasco R, Selgas MD, Cabeza MC. Effect of E-beam treatment on expression of virulence and stress-response genes of Listeria monocytogenes in dry-cured ham. Int J Food Microbiol. 2021;340:109057. doi: 10.1016/j.ijfoodmicro.2021.109057. [DOI] [PubMed] [Google Scholar]
  18. Maherani B, Harich M, Salmieri S, Lacroix M. Antibacterial properties of combined non-thermal treatments based on bioactive edible coating, ozonation, and gamma irradiation on ready-to-eat frozen green peppers: evaluation of their freshness and sensory qualities. Eur Food Res Technol. 2019;245:1095–1111. [Google Scholar]
  19. Mandel QA. Fungal contamination of some imported spices. Mycopathologia. 2005;159:291–298. doi: 10.1007/s11046-004-5496-z. [DOI] [PubMed] [Google Scholar]
  20. Mathot AG, Postollec F, Leguerinel I. Bacterial spores in spices and dried herbs: the risks for processed food. Compr Rev Food Sci Food Saf. 2021;20:840–862. doi: 10.1111/1541-4337.12690. [DOI] [PubMed] [Google Scholar]
  21. Osaili TM, Al-Nabulsi AA, Aljaafreh TF. Use of gamma radiation for inactivating Salmonella spp., Escherichia coli O157: H7 and Listeria monocytogenes in tahini halva. Int J Food Microbiol. 2018;278:20–25. doi: 10.1016/j.ijfoodmicro.2018.04.029. [DOI] [PubMed] [Google Scholar]
  22. Rahman M, Islam MA, Khan RA. Characterization of chemical elements in common spices of bangladesh for dietary intake and possible health risk assessment by INAA and AAS techniques. J Radianal Nucl Chem. 2018;318:1347–1357. [Google Scholar]
  23. Ravindran R, Jaiswal AK. Wholesomeness and safety aspects of irradiated foods. Food chem. 2019;285:363–368. doi: 10.1016/j.foodchem.2019.02.002. [DOI] [PubMed] [Google Scholar]
  24. Rico CW, Kim GR, Ahn JJ, Kim HK, Furuta M, Kwon JH. The comparative effect of steaming and irradiation on the physicochemical and microbiological properties of dried red pepper (Capsicum annum L.) Food Chem. 2010;119:1012–1016. [Google Scholar]
  25. Robichaud V, Bagheri L, Salmieri S, Aguilar-Uscanga BR, Millette M, Lacroix M. Effect of γ-irradiation and food additives on the microbial inactivation of foodborne pathogens in infant formula. LWT Food Sci Technol. 2020;139:110547. [Google Scholar]
  26. Roy MC, Alam M, Saeid A, Das BC, Mia MB, Rahman MA, Ahmed M. Extraction and characterization of pectin from pomelo peel and its impact on nutritional properties of carrot jam during storage. J Food Process Preserv. 2018;42:e13411. [Google Scholar]
  27. Siddhuraju P, Makkar HPS, Becker K. The effect of ionizing radiation on antinutritional factors and the nutritional value of plant materials with reference to human and animal food. Food Chem. 2002;78:187–205. [Google Scholar]
  28. Song WJ, Sung HJ, Kim SY, Kim KP, Ryu S, Kang DH. Inactivation of Escherichia coli O157: H7 and Salmonella Typhimurium in black pepper and red pepper by gamma irradiation. Int J Food Microbiol. 2014;172:125–129. doi: 10.1016/j.ijfoodmicro.2013.11.017. [DOI] [PubMed] [Google Scholar]
  29. Umesha S, Manukumar HM. Advanced molecular diagnostic techniques for detection of food-borne pathogens: current applications and future challenges. Crit Rev Food Sci Nutr. 2018;58:84–104. doi: 10.1080/10408398.2015.1126701. [DOI] [PubMed] [Google Scholar]
  30. Waje CK, Kim HK, Kim KS, Todoriki S, Kwon JH. Physicochemical and microbiological qualities of steamed and irradiated ground black pepper (Piper nigrum L.) J Agric Food Chem. 2008;56:4592–4596. doi: 10.1021/jf8002015. [DOI] [PubMed] [Google Scholar]
  31. Woldemariam HW, Kießling M, Emire SA, Teshome PG, Topfl S, Aganovic K. Influence of electron beam treatment on naturally contaminated red pepper (Capsicum annuum L.) powder: Kinetics of microbial inactivation and physicochemical quality changes. Innov Food Sci Emerg Technol. 2021;67:102588. [Google Scholar]
  32. Zec M, Glibetic M (2020) Biotic and abiotic safety concerns for herbs and spices. In: Hossain MB, Brunton NP, Rai DK Herbs, spices and medicinal plants: processing, health benefits and safety. John Wiley & Sons Ltd, pp 301–319
  33. Zhang D, Tan B (2021) Effects of different solid‐state fermentation ratios of S. cerevisiae and L. plantarum on Physico‐chemical properties of wheat bran and the quality of whole wheat bread. J Sci Food Agric. doi: 10.1002/jsfa.11097] [DOI] [PubMed]
  34. Zhang H, Tikekar RV, Ding Q, Gilbert AR, Wimsatt ST. Inactivation of foodborne pathogens by the synergistic combinations of food processing technologies and food-grade compounds. Compr Rev Food Sci Food Saf. 2020;19:2110–2138. doi: 10.1111/1541-4337.12582. [DOI] [PubMed] [Google Scholar]

Articles from Journal of Food Science and Technology are provided here courtesy of Springer

RESOURCES