Rheological Examination of White Pepper Slurries to Determine Prior Treatment of Pepper with Gamma-Irradiation

ABSTRACT: A study was carried out to examine rheological properties for the detection of irradiated white pepper by viscosity and maximum viscosity methods. Samples in polyethylene bags were irradiated and measured for apparent viscosity and maximum viscosity. The viscosity of all samples decreased with increasing stirring speeds and irradiation dose. This trend was similar for maximum viscosity. The results suggest that the detection of irradiated white pepper is possible by both the viscometric and maximum viscosity methods. Therefore, maximum viscosity method can be used as a new method to detect the irradiated white pepper.     

Detection of irradiation in scampi tails — effects of sample preparation, irradiation dose and storage on ESR response in the cuticle

This paper describes the potential of using ESR spectroscopy for the identification of irradiated scampi (Norway lobster) using the signal induced in the cuticle at 349.5 mT. Freeze-drying the cuticle gave a larger signal than air-drying, and peak height was found to be a more reliable method of quantification than double integration of the peak. There was a linear response with increasing irradiation dose. Samples were stored intact at –20°C and +5°C and as dry shell at room temperature for up to 84 d and it was observed that signal intensity was reduced with increased storage time and higher temperature, especially at the higher doses. Thus ESR spectroscopy can be used to detect irradiation in scampi cuticle and has potential for the estimation of irradiation dose.     

Accuracy of the Calibration Curve Method for Absorbed Dose Assessment in Irradiated Refrigerated Chicken Bone

ABSTRACT: The influence of the decay of the radiation induced free radicals on electron spin resonance (ESR) bone dosimetry was studied. The absorbed doses in irradiated bone are usually assessed by applying correction factors for decay. An alternative procedure is presented in which the ESR readout was performed only when the ESR signal had reached good stability for the bone samples used to establish the calibration curves and also on bones for which absorbed dose assessment was to be made. The results of the evaluated doses obtained by using this approach were the same as the ones obtained by using corrections for the decay of ESR signals.     

An ESR study on identification of gamma-irradiated kiwi, papaya and tomato using fruit pulp

Summary In this work we use paramagnetic defects induced by radiation in the fruit pulp to identify gamma-irradiated kiwi, papaya and tomato. Pulp without seed, peels or stalks are treated by alcoholic extraction in order to remove water, soluble fractions and solid residue. The ESR spectra of pulp samples of irradiated fruit is composed of species A (g = 2.0045) and species C (g = 2.0201 and g = 1.9851), which are also observed in irradiated stalks and skins. In comparison with samples which are not submitted to alcoholic extraction, species C is stable enough to be used as a dose marker. Furthermore, the species C signal can be detected perfectly even in pulp samples irradiated with doses as low as 200 Gy. Irradiation doses of fruit, exposed to 200–900 Gy of a gamma rays, were estimated with an overall uncertainty of 15% using dried pulp samples. These results indicate that radicals induced in pulp have potential to be used in the identification and absorbed dose determination of irradiated fruit.     

2-Dodecylcyclobutanone as an irradiation dose indicator to identify and estimate original dose in irradiated ground beef

2-Dodecylcyclobutanone (2-DCB), as a chemical marker of irradiated lipid-containing foods, was used to detect whether ground beef patties were irradiated and to estimate the original absorbed dose. The ground beef patties (70/30) were irradiated at five targeted absorbed doses of 0.5, 1.0, 3.0, 5.0, and 7.0?kGy and stored for 0, 7, 14, 21, and 28?days, respectively at 4?°C. A rapid analytical method based on direct solvent extraction (DSE)/gas chromatography–mass spectrometry (GC–MS) was developed to analyze 2-DCB in γ-ray irradiated ground beef patties. The samples were extracted with acetonitrile via DSE using a tissue-mashing instrument, and then purified with a 1-g silica cartridge and analyzed via GC–MS. The results indicate a linear relationship between irradiation dose and the amount of 2-DCB produced in the irradiated samples (y?=?0.0608x–0.0004, R2?=?0.9899). In addition, a linear relationship was observed between the loss (%) of 2-DCB and storage time (L?=?1.958d–1.6596, R2?=?0.9597). Thus, a method for estimating the initial dose of irradiated food was developed based on these two line equations; this method explored the establishment of a determination model of the original irradiation dose of lipid-containing foods. The method was used to successfully estimate 2–7?kGy irradiated beef samples within 28?days with minimal deviation within ±15?%.     

Modeling total volatile basic nitrogen production as a dose function in gamma irradiated refrigerated squid rings

The behavior of a chemical spoilage index for marine products (total volatile basic nitrogen – TVBN) was modeled as a function of the irradiation dose in Illex argentinus rings stored in refrigeration. The effect of gamma irradiation at 0, 1.8, 3.3 and 5.8 kGy on TVBN was analyzed in vacuum-packed squid rings during storage at 4 ± 1 °C. The modified Gompertz model satisfactorily described TVBN behavior for each irradiation dose (R² > 0.980; RMSE < 5.7). Gompertz model parameters (μ, A, L) were modeled with dose-dependent second order polynomials, for doses ranging between 0 and 5.8 kGy, in order to develop a complete model that is useful for predicting TVBN as a function of the dose in squid rings. Model validation was carried out using independent data of TVBN in squid rings irradiated at 4.8 kGy. The developed model can be used to predict TVBN production in gamma irradiated squid meat.     

The influence of radapertization upon some sensory properties of black pepper

Radapertization may be used as an effective method for sterilization of spices. A possible influence of irradiation upon the sensoric qualities should be considered in this context. Therefore the objectives of the work were: --to determine the influence of the irradiation of pepper upon its sensoric quality --to determine the qualitative changes of volatile chemical substances under the influence of the irradiation of pepper --to determine correlation between changes resulting from irradiation and the sensoric quality of pepper. The spice was irradiated with doses of 10, 20, 40 and 60 kGy. Thresholds of recognition and difference were determined. It was established that the quantity of the dose is related to the values of thresholds mentioned above. The larger the dose was the less intensive the flavour became and the higher the thresholds. These interdependences were written in a form of mathematical formulas. A significant influence of irradiation upon the decrease of the quantity of essential oils and carbohydrates was noticed. These relations were also presented in a form of mathematical formulas. The work provides evidence for the fact that there is a relation between the results of sensoric assessments and the chemical characteristics (the content of volatile carbonyl, sulphuric and nitrogenic substances). Correlation between these factors was determined on the basic statistical analysis of the results obtained during our investigations.     

ESR- und HPLC-Untersuchungen zum Nachweis der γ-Bestrahlung bei Eiern

Two methods for the identification of irradiated eggs are presented. Electron spin resonance (ESR) detects radiation-specific radicals in the calcite matrix of eggshells. ESR gives unequivocal results for doses clearly below the technologically relevant dose. The stability of the radical in the calcite matrix was tested over a period of 6 weeks. Products that contain no or only low amounts of fat but a high percentage of protein can be identified by HPLC. Only in the chromatograms of irradiated samples is a peak of the amino acidortho-tyrosin present. This HPLC method may be of great interest especially for the identification of irradiated pasteurized liquid egg white.     

Electron Spin Resonance Analyses of Grinding- and Radiation-Induced Signals in Raw and Refined Sugars A Comparative Study

Irradiated food containing crystalline sugar may be identified using the electron spin resonance spectroscopy (ESR) in accordance with the European standard EN 13708 2001. The method is based upon the detection of sugar radicals induced by irradiation giving a typical dose-dependent spectrum. Grinding, a common industrial process, can also produce ESR signals. In this study, the grinding-induced ESR signals were investigated for their dependence on sugar purity, grinding time, particle size, and grinding method. The results were compared with radiation-induced ESR signals. The mechanical grinding, depending mainly on grinding time, provided clear signals comparable to radiation-induced signals. The specific ESR signal corresponding to sugar radical appeared at 1 min of mechanical grinding which became clearer with the increase in grinding time and sample purity. All sugar samples upon 6 min of mechanical grinding showed comparable results to ≥10 Gy-irradiated samples. Similar results with negligible differences were found using samples of different origins. The results elaborated the detection limits of sugar containing irradiated food based on ESR analysis.     

Effect of γ-irradiation on granule structure and physicochemical properties of starch extracted from two types of potatoes grown in Jammu & Kashmir,India

In this study red and white potato starches were treated with γ-irradiation of 0, 5, 10 and 20 kGy. Physicochemical, pasting and morphological properties of the irradiated starches were investigated. Apparent amylose content, pH, moisture, swelling power and syneresis decreased; whereas carboxyl content, water absorption capacity and solubility increased with increasing irradiation dose. Pasting properties also decreased significantly (p ≤ 0.05) upon increasing the irradiation dose. Observation under scanning electron microscope (SEM) showed surface cracking of the starch granules by γ-irradiation which increased with increase in irradiation dose. X-ray diffraction pattern remained the same upon irradiation but a decrease in relative crystallinity was observed with increasing irradiation dose.     

Effect of electron beam irradiation on the shelf life of mozzarella cheese

The effectiveness of electron beam irradiation on the shelf life of mozzarella cheese was evaluated using five different irradiation doses and a control cheese. Shelf life tests were run at 10 °C by determining the cell load of spoilage micro‐organisms monitored on the consecutive days during storage. By fitting the experimental data through a modified version of the Gompertz equation, the shelf life of samples irradiated to the different doses was calculated. Results show significant increases in the shelf life of the investigated cheese. There were slight differences in the functional properties such as stretching, oiling off, melting between irradiated and unirradiated cheeses at 260 °C in oven. Our results indicated that the electron irradiation at the dose of 2.0 kGy may inhibit the growth of spoilage micro‐organisms such as coliforms and Pseudomonas sp. without affecting the sensorial characteristics of the product.     

Effects of E‐beam irradiation and vacuum packaging on biogenic amines formation in common carp (Cyprinus carpio) fillets

The effects of vacuum packaging followed by E‐beam irradiation treatment on the shelf life of common carp (Cyprinus carpio) fillets were studied by measuring biogenic amines and sensory analysis. Samples were irradiated at doses of 0.10, 0.50, 1.0 and 2.0 kGy. Putrescine, cadaverine, histamine and tyramine showed very good correspondence with the irradiation dose and the time of storage. Spermine, spermidine, tryptamine and phenylethylamine did not show statistically significant changes with the time of storage. According to the sensory assessment and biogenic amines index (BAI), the shelf life of unirradiated common carp fillets was found to be approximately seven days. The 1 and 2 kGy irradiation doses extended the shelf life of samples up to 66 and 77 days, respectively. High values of correlation coefficients (r < ?0.86) between BAI and sensory evaluation indicated that BAI could be considered as a quality indicator of common carp fillets.     

Effect of γ-irradiation on antioxidant activity of black pepper (Piper nigrum L.)

Antioxidant activity and EPR investigations of irradiated ground black pepper (Piper nigrum L.) were evaluated. The black pepper was exposed to γ-irradiation at doses from 5 to 30 kGy. The effect of irradiation on antioxidant properties of black pepper extracts was investigated by radical-scavenging effect on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, by determination of reducing power and content of thiobarbituric acid-reactive substances. Some significant changes were observed in creation of thiobarbituric acid-reactive substances (TBARS). Difference between non-irradiated and irradiated samples at the legal European limit dose of 10 kGy reached, on average, 23% and, at the Food and Drug Administration (FDA) 30 kGy limit, 33%. Irradiation affected significantly the DPPH radical-scavenging activity and reducing power of ground black pepper extracts. The γ-radiation treatment of ground black pepper samples observed by EPR, resulted in the production of three paramagnetic species (GI–GIII) characterized by different origin, thermal behaviour and stability. The axially symmetric EPR resonances, GI and GII, were assigned to the carbohydrate radical structures. The spin Hamiltonian parameters of GIII possessed the characteristic features of “cellulosic” radical species. The EPR measurements, performed 20 weeks after the radiation process, confirmed that temperature increase from 298 to 353 K, caused significant decrease of integral EPR signal intensity for γ-irradiated samples (∼40%), compared to the reference (non-irradiated) ground black pepper, where only 13% drop was found. Significant correlation between EPR and thiobarbituric acid methods was assessed by study of antioxidant activity changes in relation to irradiation doses and also in the case of spice storage, between EPR and reducing power methods.     

Free radicals in velvet bean seeds (Mucuna pruriens L. DC.) and their status after γ-irradiation and conventional processing

Free radicals in velvet bean seeds, a nutarceutically valued legume were examined by electron spin resonance (ESR) spectroscopy. The status of free radicals present naturally, after irradiation and conventional processing were recorded by entrapping small quantities of seed samples in potassium chloride powder in ESR quartz tubes. The ESR signal at g=2.0055(±0.0001) were more prominent in seed coat than cotyledon portion. Gamma irradiation of seeds (for hygienization and quarantine purposes) at different doses (0, 2.5, 5, 7.5, 10, 15 and 30 kGy) resulted in a dose-dependent increase of signal intensity at g=2.0055 in seed coat as well as in cotyledon. In seed coat, a weak triplet (satellite peak) accompanied the central line. This satellite peak (left line ‘g’) can be used as an authentic indication of radiation treatment of Mucuna seeds and can be employed as one of the detection methods for similarly irradiated legume seeds possessing prominent seed coat. In cotyledon, irradiation at high doses (15 and 30 kGy) showed a significant reduction of the ESR signals (P<0.05), which has been attributed to possible increase in free radical scavengers (particularly polyphenols). Some of the common processing practices such as microwave roasting, flame heating and pounding also generated free radicals similar to irradiation treatments. Results of the present study substantiate the suitability of employing ESR technique for detection of free radicals present naturally or produced after radiation and conventional processing. The results of this study might also be feasible for successful application of gamma irradiation of Mucuna seeds for quarantine purposes.     

Levels of 2-dodecylcyclobutanone in ground beef patties irradiated by low-energy X-ray and gamma rays

Food irradiation improves food safety and maintains food quality by controlling microorganisms and extending shelf life. However, acceptance and commercial adoption of food irradiation is still low. Consumer groups such as Public Citizen and the Food and Water Watch have opposed irradiation because of the formation of 2-alkylcyclobutanones (2-ACBs) in irradiated, lipid-containing foods. The objectives of this study were to measure and to compare the level of 2-dodecylcyclobutanone (2-DCB) in ground beef irradiated by low-energy X-rays and gamma rays. Beef patties were irradiated by low-energy X-rays and gamma rays (Cs-137) at 3 targeted absorbed doses of 1.5, 3.0, and 5.0 kGy. The samples were extracted with n-hexane using a Soxhlet apparatus, and the 2-DCB concentration was determined with gas chromatography-mass spectrometry. The 2-DCB concentration increased linearly (P < 0.05) with irradiation dose for gamma-ray and low-energy X-ray irradiated patties. There was no significant difference in 2-DCB concentration between gamma-ray and low-energy X-ray irradiated patties (P > 0.05) at all targeted doses.     

Effect of γ-irradiation on the physicochemical and sensory properties of walnuts (<Emphasis Type="Italic">Juglans regia</Emphasis> L.)

The present study evaluated physicochemical and sensory quality parameters of walnuts as a function of irradiation dose in order to determine dose levels causing minimal undesirable changes to walnuts. Physicochemical parameters including peroxide value (PV), hexanal content, fatty acid composition, volatile compounds and sensory parameters including color, texture, odor and taste were determined for unirradiated and irradiated walnuts at radiation doses of 1.0, 1.5, 3.0, 5.0 and 7.0 kGy. PV increased from 1.1 to 3.0 meq O₂/kg walnut oil while the hexanal content increased from 3.80 to 34.3 mg/kg walnut after irradiation at a dose of 7.0 kGy. Of the fatty acids determined, stearic and palmitic acids concentration increased while oleic acid decreased with irradiation dose. Polyunsaturated fatty acids were unaffected by irradiation. Volatile compounds such as aldehydes, ketones, alcohols and hydrocarbons increased after irradiation indicating enhanced lipid oxidation. Color parameter L*, a* and b* remained unaffected by irradiation. Sensory analysis showed that taste was the most sensitive of all sensory attributes for the evaluation of walnut quality. Based on taste and odor scores, walnuts remained organoleptically acceptable at doses ≤3.0 kGy.     

Radiolysis products and sensory properties of electron-beam-irradiated high-barrier food-packaging films containing a buried layer of recycled low-density polyethylene

The aim was to study the effect of electron-beam irradiation on the production of radiolysis products and sensory changes in experimental high-barrier packaging films composed of polyamide (PA), ethylene-vinyl alcohol (EVOH) and low-density polyethylene (LDPE). Films contained a middle buried layer of recycled LDPE, while films containing 100% virgin LDPE as the middle buried layer were taken as controls. Irradiation doses ranged between zero and 60 kGy. Generally, a large number of radiolysis products were produced during electron-beam irradiation, even at the lower absorbed doses of 5 and 10 kGy (approved doses for food ‘cold pasteurization’). The quantity of radiolysis products increased with irradiation dose. There were no significant differences in radiolysis products identified between samples containing a recycled layer of LDPE and those containing virgin LDPE (all absorbed doses), indicating the ‘functional barrier’ properties of external virgin polymer layers. Sensory properties (mainly taste) of potable water were affected after contact with irradiated as low as 5 kGy packaging films. This effect increased with increasing irradiation dose.     

Solid-Phase Microextraction to the Study of the Stability of Selected Volatile Constituents in Irradiated Manchego Cheese

The effect of irradiation on selected volatile constituents of Manchego cheese was examined by solid-phase microextraction-gas chromatography–mass spectrometry (SPME-GC–MS). An optimization process of the SPME procedure was carried out by considering different fiber types, extraction temperatures, and exposure times. As a result, CAR/PMDS, 40 °C and 30 min were the experimental conditions selected. The SPME-GC–MS analysis of Manchego cheese samples non-irradiated and irradiated with doses lower than 3.0 kGy demonstrated that the volatile composition is not affected by irradiation. However, the application of irradiation doses ranging between 3.0 and 8.0 kGy resulted in a modification of Manchego cheese volatiles, which increased with the dose applied.     

Application of electron paramagnetic resonance (EPR) spectroscopy for control of irradiated food

Four groups of foodstuffs were irradiated in a ⁶⁰Co source with doses from 0.3 to 10kGy and subsequently measured by EPR spectrometry at room temperature in air: (1) poultry bones and fins, scales and bones of carp. (2) seeds of selected fruits, (3) dehydrated mushrooms, and (4) a selected set of spices and herbs. Qualitative and, in some cases, quantitative data related to the absorbed dose of radiation were collected. In the irradiated bones from poultry and carp an asymmetric singlet (g_I = 2.0030, g_II =1.9973; ΔH_pp = 0.85 mT) was detected which was stable at room temperature and was similar to that previously found in irradiated mammalian bones. Another stable EPR signal (g₀ = 2.0024, ΔH_pp = 0.56 mT) was found in the fins and scales of carp which was about five times more intense in fins than in scales. In pips of pears irradiated with a dose of 3 kGy. a signal which was about twice as intense as the endogenous signal was recorded. A multicomponent EPR signal derived from the stones of dates differed from the endogenous signal even when a low dose (0-5 kGy) was applied. A multicomponent EPR signal is also observed in dried mushrooms irradiated with a dose of 3 kGy. In white mustard, paprika and chilli no native EPR signal exists and a radiation-induced stable EPR signal can still be observed after a period of 3 months. The radiation-induced EPR signal in black pepper was highly sensitive to moisture and disappeared, yet the native signal survived. The pilot experiments performed with irradiated stones of cherries, plums, lemons, apple pips, raspberries, cranberries, red currants, blackcurrants, gooseberries and tomatoes showed the induction of short-lived EPR signals of no practical use for the control of food irradiation.     

The effect of post-irradiation cooking on the ESR signal in irradiated chicken drumsticks

Groups of seventy-two, 6-week-old broiler chicken carcasses were either not irradiated and served as controls or were given 2.5 or 5.0 kGy doses of irradiation. Half of each group remained uncooked and half were cooked in a convection oven at 190°C. Pairs of drumsticks were taken from each carcass, the bones excised and the free radical content measured using electron spin resonance (ESR) spectroscopy. The ESR signal strength increased significantly as irradiation dose increased, the value at 5.0 kGy being 96% greater than that at 2.5 kGy. Cooking significantly reduced the free radical concentration of the irradiated bone by approximately 23%.