Assessment of oleoresin and gingerol contents in gamma irradiated ginger rhizomes

Oleoresin and gingerol contents in gamma irradiated dried ginger rhizomes were evaluated to determine the effect of radiation and storage on these constituents of ginger. Dried ginger rhizomes were subjected to 0, 5 and 10 kilogray (kGy) doses of gamma rays from 60Co source. The oleoresin and gingerol contents were monitored for 9 months. Radiation treatment (10 kGy) reduced the decrease of the oleoresin content of ginger during the storage period by 14% in unground samples and 11% in ground samples. There was a dose-dependent decrease in the 6-gingerol content of the ground ginger decreased by 65.6, 67.4 and 70.4% for the 0, 5, and 10 kGy samples, respectively, while the corresponding values for the ungrounded ginger samples were 37.8, 40.0 and 44.3% at the end of the storage period.     

辐照对四川泡生姜的影响

为了保证品质并减少食品添加剂的使用,采用60Co-γ射线对四川泡生姜进行辐照灭菌处理,研究辐照对泡生姜中微生物数量、乳酸含量、亚硝酸盐含量及感官评价等因素的影响。结果表明,在0-5kGy辐照剂量范围内,细菌总数及乳酸菌数随着辐照吸收剂量的增加而逐渐减少,当初始含菌量在105-106CFU/g范围内,5 kGy的辐照可将细菌总数及乳酸菌数降至100 CFU/g;泡生姜中的乳酸含量受辐照影响不大;亚硝酸盐含量随辐照吸收剂量的增加略有上升,但在0-5 kGy范围内始终远低于四川泡菜地方标准及食品安全国家标准;在实验剂量范围内,辐照对泡生姜感官无明显影响。说明60Co-γ射线辐照处理对泡生姜的总体质量没有明显影响,并可减少化学防腐剂的使用,增加食品安全,同时有效杀灭微生物,延长货架期。     

Physio-chemical behavior of γ-irradiated garlic bulbs under ambient storage conditions

The present study was undertaken to study the effect of different gamma irradiation doses on storage life of garlic bulbs under ambient storage conditions. Garlic bulbs (cv. PG-18) were irradiated with gamma rays in dose range of 0–0.2 kGy and stored under ambient conditions (Temp 27–35 °C and RH 34–76%). Physical and chemical quality parameters i.e. physiological loss in weight (plw), rotting, sprouting, total soluble solids, firmness, ascorbic acid and allicin content of garlic bulbs was determined fortnightly to assess its storage life. On 195th day of ambient storage, the weight loss of bulbs ranged from 32.22 to 38.48% in all irradiation doses. It was observed that upto 30 days and 150 days, there was no rotting and sprouting, respectively in all the treatments. Firmness, total soluble solids, ascorbic acid and allicin content were significantly different with storage period and irradiation dose levels. It is concluded that garlic bulbs irradiated @ 0.12 kGy of gamma radiation resulted in minimum post-harvest losses along with maintaining their marketable shelf life for 4 months under ambient storage conditions.     

Mold and Aflatoxin Reduction by Gamma Radiation of Packed Hot Peppers and Their Evolution during Storage

The effect of gamma radiation on moisture content, total mold counts, Aspergillus counts, and aflatoxins of three hot pepper hybrids (Sky Red, Maha, and Wonder King) was investigated. Whole dried peppers packed in polyethylene bags were gamma irradiated at 0 (control), 2, 4, and 6 kGy and stored at 25°C for 90 days. Gamma radiation proved to be effective in reducing total mold and Aspergillus counts in a dose-dependent relationship. Total mold counts in irradiated peppers immediately after treatments were significantly lowered compared with those in nonirradiated samples, achieving 90 and 99% reduction at 2- and 4-kGy doses, respectively. Aspergillus counts were significantly reduced, by 93 and 97%, immediately after irradiation at doses of 2 and 4 kGy, respectively. A radiation dose of 6 kGy completely eliminated the population of total molds and Aspergillus fungi. The evolution of total molds in control and irradiated samples indicated no further fungal proliferation during 3 months of storage at 25°C. Aflatoxin levels were slightly affected by radiation doses of 2 and 4 kGy and showed a nonsignificant reduction of 6% at the highest radiation dose of 6 kGy. The distinct effectiveness of gamma radiation in molds and aflatoxins can be explained by the target theory of food irradiation, which states that the likelihood of a microorganism or a molecule being inactivated by gamma rays increases as its size increases.     

Changes in some quality factors of frozen ginger as affected by the freezing storage conditions

The effects of types of ginger root, the freezing storage temperature and time on quality factors associated with color, off‐odor and acceptability of frozen ginger were evaluated to establish the freezing storage conditions of ginger roots. Whole and ground ginger was packed in Nylon/polyethylene (PE) bags and stored at ?5, ?20 and ?40 °C. The quality of the ginger was determined at the following times and storage temperatures: the ginger stored at ?5 °C, ?20 °C, and ?40 °C was sampled at 30‐day intervals for 4 months, at 90‐day intervals for 12 months, and at 120‐day intervals for 16 months, respectively. The content of free sugars, free amino acids (FAAs), unsaturated fatty acids (FUFAs) and volatile compounds noticeably decreased during the storage period, while the total color difference (ΔE) increased, and the temperature effect was significant. The changes in these compounds were generally less in the whole ginger samples. The overall preference of ginger roots stored at ?5, ?20 and ?40 °C was significantly different after 2–3, 9 and 16 months of storage, respectively. The increase of ΔE with decreases of free sugars, FAAs and sensory color indicated the discoloration of frozen ginger was due to the browning reaction. The sensory off‐odor scores were closely associated with the decrease of FUFAs, suggesting that the oxidation of FUFAs caused the development of off‐odor in the frozen ginger. Multiple regression analysis between the overall preference scores and other determined quality factors indicated that FAAs, FUFAs and volatile compounds significantly affected the overall preference scores of ground ginger samples stored at ?5 °C or ?20 °C. The sensory off‐odor and overall preference scores showed that whole ginger could be stored for 2 or 9 months at ?5 or ?20 °C, respectively, maintaining a good overall quality. Copyright © 2006 Society of Chemical Industry     

Shelf-Life Extension of Fresh Ginger (Zingiberofficinale) by Gamma Irradiation

ABSTRACT: Gamma irradiation was found to extend the shelf life of farm fresh ginger. A 5-kGy radiation dose and 10 °C storage temperature were found to keep peeled ginger samples microbe free and acceptable until 70 d of storage, whereas nonirradiated (control) peeled ginger spoiled within 40 d under similar storage conditions. The decrease in 6-gingerol, the compound responsible for the pungency of ginger, was found to be insignificant after irradiation.     

Effect of irradiation on the microbiological status and flavouring materials of selected spices

Spices from Egyptian local markets were irradiated with different recommended doses (0, 5, 10, 20 and 30 kGy). The spices tested included dried leaves of marjoram (Majorana hortensis Moench), rhizomes of ginger (Zingiber officinale Roscoe) and powdered hot pepper (Capsicum annum L.). The study included the isolation and identification of micro-organisms in spices following their irradiation, as well as gas Chromatographic (GLC) chemical analysis for the presence and structure of volatile oils, pungent and pigment materials. The results showed that hot pepper was contaminated more (9.2 x 10⁵/g) than marjoram (4.2 x 10³/g) and ginger (14.3 x 10³/g) with respect to total aerobic bacterial content. The total contents of moulds were 4.8 x 10³/g, 5.7 x 10³/g and 19 x 10³/g in the same spices, respectively, but the pathogenic moulds and bacterial strains differed according to the type of spice. Irradiation at 10, 20 and 30 kGy caused complete elimination of micro-organisms, whereas 5 kGy was less effective. With the GLC method chosen 18 and 50 compounds could be detected in the extracts of marjoram and ginger, respectively; -terpinen and zingiberen being the major compounds in marjoram and ginger, respectively. A noticeable reduction was observed in the amount of terpenes present in irradiated marjoram; they were converted to monoterpe-nesalcohols. Ginger was more sensitive to irradiation, especially at high doses, but moderate changes were detected at low doses (5 and 10 kGy). A slight, but significant effect on the capsaicin (pungent compound) in hot pepper was observed following irradiation, whereas no changes in total pigments resulted at any dose. These results prove that 10 kGy is a sufficiently high dose to eliminate the microorganisms in spices, causing only slight changes in the flavouring materials.     

Sensorial and chemical quality of electron beam irradiated almonds (Prunus amygdalus)

This work reports the effects of irradiation with accelerated electrons (0, 3, 7, and 10 kGy) on the chemical composition (water content, proteins, neutral detergent fiber, sugars, lipid content, organic acids, and color) and sensorial properties (rancidity, sweetness, off-flavors and odors, texture, and whiteness) of the shelled almond variety Guara, packaged under air atmosphere and stored for 5 months at 20±1 °C. Changes observed where a decrease for glucose in samples treated at all irradiation doses. An increase of citric acid, at doses above 3 kGy and then a decrease to values similar to those of the control was observed. With respect to the sensorial analysis, there was no treatment effect on the sweetness, texture or color but there was a marked rancidity in the samples treated with 10 kGy that decreased the overall appreciation of the samples. Irradiation doses of up to 7 kGy seem to be a suitable post-harvest sanitation treatment since they did not cause significant changes in the sensorial quality or in the contents of protein, fiber, water, or lipid with respect to the control samples, both following the treatments and after 5 months of storage.     

Sprouting and quality control of fresh ginger rhizomes by modified atmosphere packaging with film perforation

The quality of ginger rhizomes packaged in low density polyethylene bags (modified atmosphere packaging — MAP) without perforations (P-0), with 2 perforations (P-2), and 12 perforations (P-12) have been investigated for 5 months at 12±1°C. Sprouting and rotting rates of ginger in P-2 and P-12 were lower than ginger in P-0. Weight loss was higher in P-12 than P-0 and P-2. Surface L* (lightness) and a* (redness) values in P-2 and P-12 were lower and higher, respectively, than those found for P-0. Sensory appearance and overall acceptability were rated significantly better in P-2 and P-12 than in P-0. Internal color, firmness, soluble solids, and pH of ginger in MAP were not affected by presence of perforations. Therefore, MAP with the appropriate number of perforations (in this work, 2 perforations) could be a useful method to control sprouting and maintain quality except for surface color of stored ginger rhizomes.     

Antioxidant activity of ginger extract in sunflower oil

The antioxidant activity of dichloromethane extract from ginger was evaluated during 6 months of storage of refined sunflower oil at 25 and 45 °C. Free fatty acid (FFA) content, peroxide value (POV) and iodine value (IV) were used as criteria to assess ginger extract as an antioxidant. After 6 months of storage at 45 °C, sunflower oil containing 1600 and 2400 ppm ginger extract showed lower FFA contents (0.083 and 0.080%) and POVs (24.5 and 24.0 meq kg^?1) than the control sample (FFA contents 0.380%, POV 198.0 meq kg^?1). Sunflower oil containing 200 ppm butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) showed FFA contents of 0.089 and 0.072% and POVs of 26.5 and 24.7 meq kg^?1 respectively after 6 months of storage at 45 °C. Similarly, after 6 months of storage at 45 °C, IVs of sunflower oil containing 1600 and 2400 ppm ginger extract were 80 and 92 respectively, higher than that of the control sample (53). However, IVs of sunflower oil treated with 200 ppm BHA and BHT were 94 and 96 respectively after 6 months of storage at 45 °C. These results illustrate that ginger extract at various concentrations exhibited very strong antioxidant activity, almost equal to that of synthetic antioxidants (BHA and BHT). Ginger extract also showed good thermal stability and exhibited 85.2% inhibition of peroxidation of linoleic acid when heated at 185 °C for 120 min. Therefore the use of ginger extract in foods is recommended as a natural antioxidant to suppress lipid oxidation. © 2003 Society of Chemical Industry     

Evaluation of a microbiological method for detection of irradiation of spices

The suitability of a microbiological method, a combination of the direct epifluorescent filter technique (DEFT) and the total aerobic plate count (APC), for the detection of irradiation of spices was evaluated. The evaluation was carried out using different kinds of spices including peppers, paprika, cardamom, cinnamon, ginger; herbs such as thyme, marjoram, basil, and oregano; and garlic powder. Ground spices were tested as well as cut and whole spice samples. Samples were analysed before and after gamma-irradiation mainly with doses of 5 and 10 kGy. Two different methods (centrifugation, filtration) for sample pretreatment were compared. Differences between the DEFT count and the APC with doses of 5 and 10 kGy varied between 3.9 and 6.8 and between 5.7 and 7.5 log units, respectively. The duration of storage after irradiation had no effect on the microbiological results. When applied to fumigated samples, the method might cause confusion in the absence of chemical analyses. The results of the analyses of samples treated by an unknown process indicated that the method could, in fact, detect irradiated samples, although it could not differentiate between irradiated and heat-treated samples.     

Effect of gamma irradiation on fungal load, chemical and sensory characteristics of walnuts (Juglans regia L.)

Walnuts of the Baladi variety were treated with 0, 0.5, 1.0, 1.5 and 2.0 kGy of gamma irradiation. The irradiated and unirradiated nuts were stored at room temperature (15-18°C) and 50-70% r.h. Fungal load, proximate composition (moisture, protein, fat and ash contents), chemical changes and sensory properties of nuts were evaluated immediately after irradiation and after 12 months of storage. The results indicated that gamma irradiation reduced fungal load. The doses applied did not cause any significant change in proximate composition of walnuts. Gamma irradiation increased total acidity and decreased iodide value and volatile basic nitrogen (VBN) immediately after treatment. After 12 months of storage, gamma irradiation decreased total acidity and peroxide value and increased iodide value and VBN. No significant differences were observed between irradiated and nonirradiated samples in flavor and aroma immediately after irradiation. After 12 months of storage, higher doses (1.5 and 2.0 kGy) had a negative effect on sensory characteristics.     

辛辣蔬菜中的杀菌素对柑桔青,绿霉菌的抑制作用

大蒜、洋葱、生姜等蔬菜含有杀菌素。采用悬滴法进行毒力测定结果表明:大蒜、洋葱、生姜的汁液对柑桔青、绿霉菌均有抑制和杀灭作用,其中大蒜的抑菌作用性能最强,洋葱次之,生姜则较差。用2．5%大蒜汁或10%洋葱汁均可抑制90%以上的青、绿霉菌孢子发芽,而12.5%生姜汁只能抑制35%~60%的孢子发芽。2．5%大蒜汁、10%洋葱汁和40%生姜汁对防治柑桔青霉病有较好的防治效果。     

High Performance Liquid Chromatographic Determination of Pungent Gingerol Compounds of Ginger (Zingiber officinale Roscoe)

The pungent gingerol compounds of green (4–5 months) and dry (8–9 months) ginger (Zingiber officinale Roscoe) were extracted by acetone and analyzed directly by high performance liquid chromatography (HPLC) on a reverse phase column (RP-18). The total gingerol content (6-, 8- and 10-gingerol) of green ginger ranged from 0.65–0.88% (w/w) while that of dry ginger varied from 1.10–1.56% (w/w).     

Einfluß der Gamma-Bestrahlung auf die Lipidkomponente von Sojaproteinprodukten

Effect of gamma irradiation on lipid components of soya protein products. The study deals with the effects of gamma irradiation at doses of 1,3 and 5 kGy on lipid components of soya protein products. Though the above irradiation doses do not induce changes in lipid and phospholipid content, they effect significant changes in the relationship among fatty acids. Compared with untreated samples, irradiation doses of 3 and 5 kGy caused significant changes (p ≦ 0,05 and p ≦ 0,01) in the correlation between fatty acids. The 1 kGy dosis did not produce significant changes in the correlation between fatty acids. The degree of lipid oxydation heightened with the increase in the dose of irradiation. Compared with controls, the content of total carotenoid pigments decreased in the irradiated samples; the mean decrease ranged from 6,0% to 16,8%. The irradiation treatment applied significantly reduced total germinating bacteria count and those of aerobic sporogenic bacteria and mold spores.     

超临界CO2萃取食用姜油的研究

用超临界CO2(SFE-CO2)流体从干姜中萃取(小试、中试)出姜油,对姜油进行GC-MS分析.实验结果表明,姜油含有49种成分,其中姜的特征成分姜辣素高达22.9%.SFE-CO2法萃取姜油能保持生姜特有的风味和辣味,油质量显著提高,该油是食品工业的优质原料.     

Free D-amino acids determination in ready-to-eat cooked ham irradiated with electron-beam by indirect chiral HPLC

Potential racemization of L-amino acids (AA) in ready-to-eat (RTE) cooked ham after hygienization by electron-beam irradiation between 1 and 8 kGy was studied. An indirect chiral method based on the derivatization reaction of AA with o-phthaldialdehyde and N-acetyl-L-cysteine followed by reversed-phase HPLC and fluorimetric detection was applied to detect ten enantiomeric pairs of free AA (Asp, Ser, Thr, Ala, Tyr, Val, Trp, Phe and Leu). Five of the D-AA were not found in any of the samples analyzed; the other five remaining D-AA (D-Asp, D-Ser, D-Ala, D-Val and D-Leu) were detected both in irradiated and non-irradiated cooked ham samples, their content being in the range 1.25–13.79 μg/g. Although significant differences appeared for a few of the samples and doses, no positive correlation between the D-AA content and the irradiation doses was observed. Therefore, the electron-beam irradiation technique could be useful for sanitation of packed RTE cooked ham at doses allowed by WHO and EU, since it remains chemically safe to eat.     

Degradation of the natural mutagenic compound safrole in spices by cooking and irradiation

Safrole was determined using gas-liquid chromatography in some common spices as star anise, cumin, black pepper and ginger. Safrole concentration in these spices was 9325, 3432, 955 and 500 mg · kg^?1, respectively. Black pepper was chosen to use in the following experiments. Using Ames-test with Salmonella TA 98 and TA 100 proved high cytotoxic effects due to pure safrole and black pepper volatile oil in both of them. The degradation of safrole was obvious after drying of the washed seeds of black pepper especially at 70 °C for 30 min or with sun-drying. Also, high irradiation doses (20 and 30 kGy) caused high degradation of more than 90% of the initial toxic concentration in black pepper. Whereas, microwave caused same effects at 75 s, but unfortunately, the powder was burned due to moisture absence. Boiling whole seeds or powder of black pepper during cooking for few minutes (1-5 min) were more efficient in decreasing safrole content. Finally, these results proved that the mutagenicity of some spices due to presence of safrole can be destructed during drying of the washed seeds or during cooking either with or without any additional treatment as irradiation. But irradiation of these spices became more necessary for using in some food industries as milk products to get more safe for human consumption.     

不同时期生姜加工品质及姜油树脂成分分析

为确定原料生姜的加工特性,研究分析了其根茎在不同生育期及贮藏期的主要成分变化。结果表明,生姜根茎干物质、可溶性糖、可溶性淀粉、粗纤维和姜油树脂等含量均随生育期和贮藏期的延长而增加,而可溶性蛋白和游离氨基酸含量则在生姜生长前期较高,生长后期及贮藏期较低且无显著变化。生姜生长过程中,姜油树脂化学成分增加,而生姜贮藏过程中,虽有新的化合物生成,但随着贮藏期的延长,姜油树脂中的β-萜品醇、橙花醛、乙酸龙脑酯等14种痕量挥发性成分消失,但不同时期生姜根茎姜油树脂的主要成分基本相同。生姜播后4～5个月,根茎产量达较高水平,且干物质及姜油树脂含量较低,辛辣味较淡,粗纤维较少,适于腌渍加工;而生姜贮藏60d后,根茎干物质、可溶性淀粉及姜油树脂含量已基本稳定,适于生姜脱水、淀粉加工及姜油提取。     

Effect of irradiation on vitamin C content of strawberries and potatoes in combination with storage and with further cooking in potatoes

The vitamin C content of four varieties of strawberry was determined before and after treatment with ionising radiation at doses of 1, 2 or 3 kGy and after storage for 5 and 10 days at 6°C, and also in potatoes which, having been allowed a period of one month to recover from the effects of post-harvest stress, were irradiated at a sprout inhibition dose of 0·15 kGy, followed by storage and cooking. Total ascorbic acid (TAA), ascorbic acid (AA) and dehydroascorbic acid (DHAA) concentrations were measured using the technique of ion-exclusion high-performance liquid chromatography. Results from analysis of the strawberry samples showed the DHAA content increased immediately following irradiation and must, therefore, be taken into account when reporting vitamin C levels in irradiated produce. In addition it was observed that whilst irradiation did affect the vitamin C concentration in all varieties of strawberry, the change was small in comparison with the large variations observed between varieties. With regard to potatoes results showed that, whilst irradiation, storage and cooking all had the effect of reducing vitamin C concentration, irradiated samples stored for 5 months had similar or marginally higher levels than their non-irradiated counterparts. Cooking did not markedly reduce TAA content of irradiated potatoes compared to non-irradiated potatoes and it was also noted that microwave cooking was more destructive than boiling in lightly salted water. ©1997 SCI