Shortening the Edinburgh postnatal depression scale using optimal test assembly methods: Development of the EPDS-Dep-5

AIMS

This study used a large database to develop a reliable and valid shortened form of the Edinburgh Postnatal Depression Scale (EPDS), a self-report questionnaire used for depression screening in pregnancy and postpartum, based on objective criteria.

METHODS

Item responses from the 10-item EPDS were obtained from 5157 participants (765 major depression cases) from 22 primary screening accuracy studies that compared the EPDS to the Structured Clinical Interview for DSM (SCID). Unidimensionality of the EPDS latent construct was verified using confirmatory factor analysis, and an item response theory model was fit. Optimal test assembly (OTA) methods identified a maximally informative shortened form for each possible scale length between 1 and 9 items. The final shortened form was selected based on pre-specified validity and reliability criteria and non-inferiority of screening accuracy of the EPDS as compared to the SCID.

RESULTS

A 5-item short form of the EPDS (EPDS-Dep-5) was selected. The EPDS-Dep-5 had a Cronbach's alpha of 0.82. Sensitivity and specificity of the EPDS-Dep-5 for a cutoff of 4 or greater were 0.83 (95% CI, 0.73, 0.89) and 0.86 (95% CI, 0.80, 0.90) and were statistically non-inferior to the EPDS. The correlation of total scores with the full EPDS was high (r = 0.91).

CONCLUSION

The EPDS-Dep-5 is a valid short form with minimal loss of information when compared to the full-length EPDS. The EPDS-Dep-5 was developed with OTA methods using objective, pre-specified criteria, but the approach is data-driven and exploratory. Thus, there is a need to replicate results of this study in different populations.

Depression prevalence based on the Edinburgh Postnatal Depression Scale compared to Structured Clinical Interview for DSM DIsorders classification: Systematic review and individual participant data meta-analysis

OBJECTIVES

Estimates of depression prevalence in pregnancy and postpartum are based on the Edinburgh Postnatal Depression Scale (EPDS) more than on any other method. We aimed to determine if any EPDS cutoff can accurately and consistently estimate depression prevalence in individual studies.

METHODS

We analyzed datasets that compared EPDS scores to Structured Clinical Interview for DSM (SCID) major depression status. Random-effects meta-analysis was used to compare prevalence with EPDS cutoffs versus the SCID.

RESULTS

Seven thousand three hundred and fifteen participants (1017 SCID major depression) from 29 primary studies were included. For EPDS cutoffs used to estimate prevalence in recent studies (≥9 to ≥14), pooled prevalence estimates ranged from 27.8% (95% CI: 22.0%-34.5%) for EPDS ≥ 9 to 9.0% (95% CI: 6.8%-11.9%) for EPDS ≥ 14; pooled SCID major depression prevalence was 9.0% (95% CI: 6.5%-12.3%). EPDS ≥14 provided pooled prevalence closest to SCID-based prevalence but differed from SCID prevalence in individual studies by a mean absolute difference of 5.1% (95% prediction interval: -13.7%, 12.3%).

CONCLUSION

EPDS ≥14 approximated SCID-based prevalence overall, but considerable heterogeneity in individual studies is a barrier to using it for prevalence estimation.

Overestimation of Postpartum Depression Prevalence Based on a 5-item Version of the EPDS: Systematic Review and Individual Participant Data Meta-analysis

OBJECTIVE

The Maternal Mental Health in Canada, 2018/2019, survey reported that 18% of 7,085 mothers who recently gave birth reported "feelings consistent with postpartum depression" based on scores ≥7 on a 5-item version of the Edinburgh Postpartum Depression Scale (EPDS-5). The EPDS-5 was designed as a screening questionnaire, not to classify disorders or estimate prevalence; the extent to which EPDS-5 results reflect depression prevalence is unknown. We investigated EPDS-5 ≥7 performance relative to major depression prevalence based on a validated diagnostic interview, the Structured Clinical Interview for DSM (SCID).

METHODS

We searched Medline, Medline In-Process & Other Non-Indexed Citations, PsycINFO, and the Web of Science Core Collection through June 2016 for studies with data sets with item response data to calculate EPDS-5 scores and that used the SCID to ascertain depression status. We conducted an individual participant data meta-analysis to estimate pooled percentage of EPDS-5 ≥7, pooled SCID major depression prevalence, and the pooled difference in prevalence.

RESULTS

A total of 3,958 participants from 19 primary studies were included. Pooled prevalence of SCID major depression was 9.2% (95% confidence interval [CI] 6.0% to 13.7%), pooled percentage of participants with EPDS-5 ≥7 was 16.2% (95% CI 10.7% to 23.8%), and pooled difference was 8.0% (95% CI 2.9% to 13.2%). In the 19 included studies, mean and median ratios of EPDS-5 to SCID prevalence were 2.1 and 1.4 times.

CONCLUSIONS

Prevalence estimated based on EPDS-5 ≥7 appears to be substantially higher than the prevalence of major depression. Validated diagnostic interviews should be used to establish prevalence.

Trends in the incidence, rate and treatment of miscarriage-nationwide register-study in Finland, 1998-2016

STUDY QUESTION

What changes have occurred in the incidence of miscarriage, its treatment options, and the profile of the women having miscarriages in Finland between 1998 and 2016?

SUMMARY ANSWER

The annual incidence of registry-identified miscarriage has declined significantly between 1998 and 2016, and non-surgical management has become the dominant treatment.

WHAT IS KNOWN ALREADY

Miscarriage occurs in 8-15% of clinically recognized pregnancies and in ~30% of all pregnancies. Increasing maternal age is associated with an increasing risk of miscarriage. The treatment of miscarriage has evolved significantly in recent years: previously, surgical evacuation of the uterus was the standard of care, but nowadays medical and expectant management are increasingly used.

STUDY DESIGN, SIZE, DURATION

We conducted a nationwide retrospective cohort study of 128 381 women that had experienced a miscarriage that was managed in public healthcare between 1998 and 2016 in Finland.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We used the National Hospital Discharge Registry for the data. Women aged 15-49 years that had experienced their first miscarriage during the follow-up period and had miscarriage-related diagnoses during their admission to public hospital were included in the study. Miscarriages were defined by the 10th Revision of the International Statistical Classification of Diseases and related Medical Problems (ICD-10) diagnostic codes O02*, O03* and O08*. Women with ectopic, molar and continuing pregnancies and induced abortions were excluded. Treatment was divided into surgical and non-surgical treatment using the surgical procedure codes.

MAIN RESULTS AND THE ROLE OF CHANCE

The annual incidence of registry-identified miscarriage has declined from 6.8/1000 15-49-year-old women in 1998 to 5.0/1000 in 2016 (P < 0.001). Also, the incidence rate of registry-identified miscarriage (i.e. the proportion of miscarriages of registry-identified pregnancies [i.e. deliveries, induced abortions, and miscarriages]) has declined from 112/1000 15-49-year-old pregnant women in 1998 to 83/1000 in 2016 (P < 0.001). The largest decrease in this proportion occurred among women over 40 years of age, among whom 26.5% of registry-identified pregnancies in 1998 ended in miscarriage compared to that of 16.4% in 2016. The proportion of missed abortion has increased (30.3 to 38.8%, P < 0.001) whereas that of blighted ovum has decreased (25.4 to 12.8%, P < 0.001). The proportion of registry-identified miscarriages seen among nulliparous women has increased from 43.7 to 49.6% (P < 0.001). Mean age at the time of miscarriage remained at 31 years throughout the study. Altogether, 29% of all miscarriages were treated surgically and 71% underwent medical or expectant management. The proportion of surgical management has decreased from 38.0 to 1.6% for spontaneous abortion, from 60.7 to 9.4% for blighted ovum and 70.9 to 11.2% for missed abortion between 1998 and 2016.

LIMITATIONS, REASONS FOR CAUTION

This study includes only women with registry-identified pregnancies, i.e. women who were treated in public hospitals. However, the number of women treated elsewhere is presumed to be small. Neither can this study estimate the number of women having spontaneous miscarriage with no hospital contact.

WIDER IMPLICATIONS OF THE FINDINGS

Both the annual incidence and incidence rate of miscarriage of all registry-identified pregnancies has decreased, and non-surgical management has become the standard of care. These findings are of value when planning allocation of healthcare resources and at individual level considering fertility and miscarriage questions. We speculate that improving ultrasound diagnostics explains the increasing proportion of missed abortion relative to other types of miscarriage. More investigation is needed to examine potential risk factors, complications and morbidity associated with miscarriages.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the research funds of the Helsinki and Uusimaa hospital system, by a personal grant from Viipurin Tuberkuloosisäätiö to R.L. and by a personal grant from The Finnish Cultural Foundation to N.H. The authors have no conflicts of interest to declare.

Does Birth-Related Trauma Last? Prevalence and Risk Factors for Posttraumatic Stress in Mothers and Fathers of VLBW Preterm and Term Born Children 5 Years After Birth

Previous research suggests that the birth of a preterm child with very low birth weight (VLBW; <1,500 g) can be traumatic for both parents and lead to short-term consequences like clinical levels of posttraumatic stress symptoms (PTSS) or even to the development of a Posttraumatic Stress Disorder (PTSD). However, little is known about possible mid- and long-term psychological consequences in affected parents. The purpose of this study were (a) to examine the prevalence of parental birth-related PTSS and PTSD in a group of parents with VLBW preterm infants compared to parents of full-term infants 5 years after birth and (b) to investigate potential associations with risk factors for parental PTSS at 5 years postpartum. Perinatal factors (VLBW preterm or term, perceived stress during birth), psychological factors (perceived social support and PTSS 4-6 weeks postpartum, psychiatric lifetime diagnosis) and sociodemographic characteristics (number of children, singleton or multiple birth, socio-economic status), were included in the analysis. The sample consisted of 144 families (77 VLBW, 67 term birth) who participated in the prospective longitudinal cohort study "Hamburg study of VLBW and full-term infant development" (HaFEn-study) and were initially recruited at three perinatal care centers in Hamburg, Germany. PTSD prevalence and PTSS of mothers and fathers were assessed with the Impact of Event Scale-Revised (IES-R), social support with the Questionnaire of Social Support (SOZU-K-22), and lifetime psychiatric diagnoses with the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (SCID-I). Data were analyzed by hierarchic multiple regression analyses. Results showed that 5 years after birth none of the parents fulfilled the criteria for a birth-related PTSD diagnosis. For mothers, postnatal PTSS and a VLBW preterm birth significantly predicted PTSS 5 years postpartum. For fathers, psychiatric lifetime diagnosis and postnatal PTSS significantly predicted PTSS 5 years after birth. Early identification of parents with higher risk of PTSS, especially after VLBW preterm birth, and their clinical needs seems beneficial to reduce the risk of long-term consequences. More research is needed on the paternal perspective and on potential effects of preterm birth on both parents and their children's mental health outcomes.

Comparison of major depression diagnostic classification probability using the SCID, CIDI, and MINI diagnostic interviews among women in pregnancy or postpartum: An individual participant data meta-analysis

OBJECTIVES

A previous individual participant data meta-analysis (IPDMA) identified differences in major depression classification rates between different diagnostic interviews, controlling for depressive symptoms on the basis of the Patient Health Questionnaire-9. We aimed to determine whether similar results would be seen in a different population, using studies that administered the Edinburgh Postnatal Depression Scale (EPDS) in pregnancy or postpartum.

METHODS

Data accrued for an EPDS diagnostic accuracy IPDMA were analysed. Binomial generalised linear mixed models were fit to compare depression classification odds for the Mini International Neuropsychiatric Interview (MINI), Composite International Diagnostic Interview (CIDI), and Structured Clinical Interview for DSM (SCID), controlling for EPDS scores and participant characteristics.

RESULTS

Among fully structured interviews, the MINI (15 studies, 2,532 participants, 342 major depression cases) classified depression more often than the CIDI (3 studies, 2,948 participants, 194 major depression cases; adjusted odds ratio [aOR] = 3.72, 95% confidence interval [CI] [1.21, 11.43]). Compared with the semistructured SCID (28 studies, 7,403 participants, 1,027 major depression cases), odds with the CIDI (interaction aOR = 0.88, 95% CI [0.85, 0.92]) and MINI (interaction aOR = 0.95, 95% CI [0.92, 0.99]) increased less as EPDS scores increased.

CONCLUSION

Different interviews may not classify major depression equivalently.

Development of Reference Materials for Paralytic Shellfish Poisoning Toxins

A project was undertaken to develop mussel reference materials that were certified for their mass fractions of saxitoxin and decarbamoyl-saxitoxin. Fifteen laboratories from various European countries participated. Three of these had major responsibility for substantial parts of the work and overall coordination of the project. The project involved 4 main activities: (1) procurement and characterization of calibrants; (2) improvement of analytical methodology; (3) preparation of reference materials, including homogeneity and stability studies; (4) 2 interlaboratory studies and a certification exercise. The joint activities resulted in 3 homogeneous and stable reference materials: 2 lyophilized mussel materials with and without naturally incurred paralytic shellfish poisoning (PSP) toxins, and a saxitoxin enrichment solution. The reference materials were certified with respect to their saxitoxin and decarbamoyl-saxitoxin content. The lyophilized mussel material with PSP toxins (CRM 542) contained &lt;0.07 mg saxitoxin·2HCl/kg and 1.59 ± 0.20 mg decarbamoyl-saxitoxin·2HCl/kg. The lyophilized mussel material without PSP toxins (CRM 543) contained &lt;0.07 mg saxitoxin·2HCl/kg and &lt;0.04 mg decarbamoyl-saxitoxin·2HCl/kg. The certified value of the saxitoxin mass fraction in the saxitoxin enrichment solution (CRM 663) was 9.8 ± 1.2 μg/g.

Internalizing symptoms in very low birth weight preschoolers: Symptom level and risk factors from four rating perspectives in a controlled multicenter study

BACKGROUND

Preterm births rates of infants with very low birth weight (VLBW < 1500 g) are increasing. Prematurity poses several risks for emotional child development, e.g., internalizing symptoms. Our understanding of this condition in young children is limited, for at preschool age, symptoms have mostly been assessed from the mother's perspective only.

METHODS

As part of the longitudinal HaFEn cohort-study in Hamburg, Germany, we measured the level of internalizing symptoms in VLBW and term preschoolers as well as predictors from four informants' perspectives: mother, father, teacher, and child. A multilevel model was constructed to examine predictors of internalizing symptoms. n = 104 VLBW and n = 79 term children were included.

RESULTS

From both their parents' perspective, children with VLBW had a significantly higher level of internalizing symptoms. From the teacher's and child's own perspectives, there were no significant mean group differences. In the multilevel analyses, the results were different regarding the four perspectives. VLBW did not predict internalizing symptoms. From mother's perspective, her own postpartum psychological distress, and from father's perspective, his postpartum and current psychological distress predicted a higher level of internalizing symptoms in their offspring. From teacher's perspective, socio-economic status predicted internalizing symptoms.

LIMITATIONS

The sample size was relatively small. Exclusion criteria and drop out of families could have created some selection bias.

CONCLUSIONS

Our findings point to the importance of early identification of parental postpartum psychological distress given the potential for later internalizing symptoms in their children or the perception of their offspring as vulnerable and symptomatic, which may also impact the child's development.

Postpartum posttraumatic and acute stress in mothers and fathers of infants with very low birth weight: Cross-sectional results from a controlled multicenter cohort study

BACKGROUND

The birth of a preterm infant can be stressful and traumatic for parents and may cause posttraumatic stress symptoms and disorders. There is a dearth of data from controlled studies regarding level, prevalence, risk, and predictors of these symptoms in parents after preterm birth.

METHODS

As part of the longitudinal HaFEn-study, data from parents of infants with very low birth weight (VLBW), and term infants were cross-sectionally analyzed. We recruited parents at the three largest perinatal care centers in Hamburg, Germany. Posttraumatic stress symptoms were assessed with a standardized questionnaire, and acute and posttraumatic stress disorders with a clinical interview one month postpartum. Stress during birth, lifetime psychiatric diagnoses, social support, pregnancy risks, and mode of delivery were also evaluated. To examine predictors of posttraumatic stress symptoms in both parents simultaneously, we constructed multiple random coefficient models.

RESULTS

230 mothers and 173 fathers were included. The risk for acute stress disorder was increased in mothers with VLBW infants but not in fathers. While the risk for posttraumatic stress disorder was not elevated, the level of posttraumatic stress symptoms was higher in both parents with VLBW infants. Predictors for posttraumatic stress symptoms were stress during birth, low social support, psychiatric lifetime diagnoses, the birth of a VLBW infant, and female parent sex.

LIMITATIONS

Results reported here are cross-sectional. Thus, no temporal relationships can be established.

CONCLUSIONS

Although posttraumatic stress disorders were rare, our results suggest that posttraumatic stress symptoms and acute stress disorders are common in parents of VLBW infants.

Is very low infant birth weight a predictor for a five-year course of depression in parents? A latent growth curve model

BACKGROUND

A very low birth weight (VLBW) is considered as a significant risk factor for early-onset developmental problems in infants, but is also discussed as a potential risk factor for the development of depressive symptoms in affected parents.

METHODS

In this study, the 5-year courses of maternal and paternal depression with VLBW and term born infants (n = 250 families) are modeled and predicted by factors existing at the time of birth.

RESULTS

The dyadic trajectories of depression could be best described by five classes (I no depression, II minor maternal depression, III increasing dyadic depression, IV significant maternal depression, V highly depressed mothers). VLBW was a significant predictor for the course of parental depression - even under control of preexisting psychiatric disorders and other confounders. Interaction effects and a dose-response relationship were not existent.

LIMITATIONS

Class IV and V had to be merged for the prediction analysis, a missing bias could not be ruled out, and families with a low birth weight (between 2500 and 1500g) were not included.

CONCLUSIONS

The results are well in line with what is known from studies so far, suggesting that maternal and paternal trajectories of depression show distinctable patterns which are associated with a VLBW. An early screening of mothers and fathers of a VLBW infant seems reasonable to prevent the development of a depression in parents and further difficulties for the child.

Postpartum anxiety and adjustment disorders in parents of infants with very low birth weight: Cross-sectional results from a controlled multicentre cohort study

BACKGROUND

Both preterm delivery and survival rates of very low birth weight (VLBW: <1500 g) infants are increasing. To date, the focus on studies about postpartum mental health after preterm birth has been on depression and on women. There is a paucity of research regarding prevalence, risks, and predictors of postpartum anxiety in parents after VLBW birth.

METHODS

Parents with VLBW infants and parents with term infants were recruited into the longitudinal HaFEn-study at the three largest centers of perinatal care in Hamburg, Germany. State anxiety was assessed with the State-Trait-Anxiety Inventory and anxiety and adjustment disorders with a clinical interview one month postpartum. Psychiatric lifetime diagnoses, social support, trait anxiety, stress during birth, socioeconomic status, risks during pregnancy, and mode of delivery were also evaluated. To examine predictors of postpartum state anxiety in both parents simultaneously a multiple random coefficient model was used.

RESULTS

230 mothers and 173 fathers were included. The risk for minor/major anxiety symptoms and adjustment disorders was higher in parents with VLBW infants compared to the term group. The risk for anxiety disorders was not higher in parents with VLBW infants. The most important predictors for postpartum state anxiety were high trait anxiety, the birth of a VLBW infant, high stress during birth, and low social support.

LIMITATIONS

Data reported here are cross-sectional. Thus, temporal relationships cannot be established.

CONCLUSIONS

Our results emphasize the importance of early screening for postpartum anxiety in both parents with VLBW infants.

Very low birth-weight as a risk factor for postpartum depression four to six weeks postbirth in mothers and fathers: Cross-sectional results from a controlled multicentre cohort study

BACKGROUND

Preterm birth and survival rates of very low birth-weight (VLBW: <1.500g) infants have increased. Although new parents are frequently affected by depressive symptoms, little is known about prevalence, risk, and predictors of parental postpartum depression (PPD) following VLBW birth. Furthermore, most studies assessing PPD in parents of preterm children relied on self-report only.

METHODS

As part of the HaFEn cohort-study, data from the index groups of parents with VLBW infants and the control group of parents with term infants were cross-sectionally analysed. Families were recruited at the three largest centres of perinatal medical care in Hamburg, Germany. PPD was evaluated one month postpartum using standardized questionnaires and clinical interviews. Socioeconomic status, social support, risks during pregnancy, and psychiatric lifetime diagnoses were also assessed. A multiple random coefficient model was used to examine predictors of PPD in both parents simultaneously.

RESULTS

230 mothers and 173 fathers were included. Depending on the measure, the risk of being postnatally depressed was 4 to 18 times higher in mothers and 3 to 9 times higher in fathers from the index group. The most relevant risk factor for PPD was the birth of a VLBW infant, followed by female sex, lifetime psychiatric disorder, and low social support.

LIMITATIONS

Results presented here, are based on cross sectional data. Therefore no temporal relationships can be established.

CONCLUSIONS

Our findings highlight the importance of early screening for PPD in both parents of VLBW infants. Factors contributing to developing depression should also be considered in neonatal care.

[The content of biogenic amines in canned fish from the Turkish market]

This paper describes the determination of biogenic amines in a number of canned fish of the Turkish market by means of HPLC. Over all 39 cans of sardine, tuna, sardel, mackerel, pelamide and trout were tested. The determination of agmatine, cadaverine, histamine, putrescine and tyramine was performed by HPLC with post column derivatization with ortho-phthaldialdehyde. Four samples contained higher amounts of biogenic amines (three sardine samples contained more than 1000 mg/kg histamine) while all other samples were acceptable. These results demonstrate the need of instrumental analyses in the quality control system of Turkish producers of canned fish. The quality of the products at least of some producers has to be improved, e.g. by cooperation between the official food control and the quality assurance system of the producers.

[Electron spin resonance spectroscopy investigations of fresh fruit. Evidence of treatment with ionizing radiation]

This paper describes the development of a method for the identification of irradiated fresh fruits by measurement of the e.p.r. spectra of pips, kernels or stones. Measurement parameters were optimized and the irradiation specific spectrum was assigned to a cellulose radical by comparison with the e.p.r. spectrum of pure cellulose. Several fruits especially different varieties of strawberries were examined giving the following results: Detectable minimum doses were between 0.4 kGy and 0.9 kGy and the intensity of the irradiation specific signals was found to be linear up to doses of 11 kGy. The lifetime of the specific radicals (at room temperature and at deep freezing temperatures) was long enough compared to the storage time of fresh fruits. Additional information about the nature of the unspecific central signal was gained measuring the samples which were stored at different temperatures. The main conclusion of this study is that the e.p.r. method seemes to be well suited for the use in routine control and should be tested in an intercomparison to establish a routine method for the identification of irradiated fresh fruits.

[Electron spin resonance measurements on dried fruit. Carbohydrate composition and ESR signal structure of irradiated fruit]

While in a previous work the ESR spectroscopic detection of irradiated dried fruits was reported, in this paper liquid chromatographic determination of the carbohydrate fraction of these fruits is introduced and connected with the ESR results. After irradiation of dried fruits three different types of ESR spectra are observed. In most cases the dried fruits can be attached to these various types by means of their sugar composition. It was also found that the ESR spectra observed for sucrose-rich fruits are very similar to that of pure sucrose. The structure of the ESR spectra can change with storage. Probably, radical rearrangement reactions in the samples are responsible for these changes.

Evaluation of a gas chromatographic method to identify irradiated chicken, pork, and beef by detection of volatile hydrocarbons

A method suitable for routine application was used in an interlaboratory study to detect irradiation treatment of chicken carcass, pork, and beef. By using gas chromatographic analysis, 17 participating laboratories determined the quantity of 4 different radiation-induced volatile hydrocarbons (tetradecene, pentadecane, hexadecadiene, and heptadecene) in the fat fraction of coded specimens approximately 3 and 6 months after irradiation. The specimens of each type of meat were supplied by 2 different producers. The dose range tested (0.6-7.5 kGy) included levels commercially used to reduce the number of contaminating microorganisms (1-5 kGy). The method employed permitted a correct identification of irradiated or nonirradiated in 98.3% of the 864 specimens.

[ESR and HPLC studies of the detection of gamma irradiation of eggs]

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 acid ortho-tyrosine present. This HPLC method may be of great interest especially for the identification of irradiated pasteurized liquid egg white.

[Identification of irradiated pasteurized egg products: a combined method for use in routine control]

Pasteurized egg products (whole egg, egg yolk and egg white) were tested for irradiation treatment in the German food control laboratories in Oldenburg/Niedersachsen and Kassel/Hessen as well as in the food irradiation laboratory of the German federal health office. Gas chromatographic/mass spectrometric measurements on the fat components of egg-products showed clearly whether the product had been irradiated or not. While in unirradiated samples no traces of special hydrocarbons (according to the fatty acid composition of egg) and no traces of the irradiation-specific compound 2-Dodecyl-cyclobutanone were found, irradiated control samples as well as products of two Belgian suppliers contained these substances. Additionally, regarding the rather high time consumption of gas chromatography, electron spin resonance (ESR)-measurements were carried out on the packaging material of egg products. Irradiated packaging material (cellulose) could be easily detected by the appearance of a signal pair in the ESR spectrum (cellulose radical). ESR measurements are very fast and easy to perform so that this method can be used for screening. Microbiological investigations showed remarkably reduced total numbers of microorganisms for some irradiated samples, but the microbiological status is influenced by other factors like storage-time and -temperature, so that microbiological tests can not be used successfully for screening on irradiation treatment.

Detection of irradiated food--methods and routine applications

Irradiation of food for the purpose of extension of shelf life, control of microbial load, reduction of pathogenic microorganisms and disinfection is regarded by many consumers with suspicion. One reason is the lack of methods within food-controlling laboratories which can detect irradiation treatment and which are applied to control correct labelling. This review describes the potential of various methods to reveal irradiation treatment. Special emphasis is given to the three most successful methods, thermoluminescence, electron spin resonance spectroscopy and detection of volatiles. The possibilities and limitations of applying the methods in routine control are discussed.

[Electron spin resonance spectroscopy as probes for spices. Detection of treatment with ionizing radiation]

Detection of irradiated spices by electron spin resonance (ESR) measurements was not successful in the past because a central line of unknown origin was detected in the ESR-spectra of both irradiated and unirradiated samples. Identification of irradiated samples by measuring the increase of intensity of this signal after irradiation is limited because the signal intensity decreases over a period of some weeks of storage and reaches the range of unirradiated samples. By changing the measurement conditions (low microwave power) we could detect two additional lines on both sides of the main signal. This line pair appears only in the spectra of irradiated spices. A similar line pair was found in the spectra of irradiated nutshells and possibly derives from cellulose radicals in the sample. For some spices, especially paprika, the identification of irradiated samples by detecting these additional lines was possible even after relatively long periods of storage.