Cooking Methods for Preserving Isothiocyanates and Reducing Goitrin in Brassica Vegetables

Glucosinolates in Brassica vegetables can be hydrolyzed into various products, e.g., chemopreventive agents, isothiocyanates (ITCs) and anti-thyroid substance, goitrin. Cooking can reduce goitrin but destroy isothiocyanates. This study aimed to optimize cooking conditions for reducing goitrin while preserving isothiocyanates in Brassica vegetables. Cabbage and Chinese kale samples were divided evenly into raw, blanched, steamed, and water-based stir-fried samples. Cooking temperature and time were varied at 60, 80, or 100 °C for 2, 4, or 6 min. The levels of goitrin, benzyl isothiocyanate (BITC), and sulforaphane (SFN) were measured using LC-MS/MS. Response surface model (RSM) was used to identify the optimal cooking conditions to reduce goitrin but preserve ITCs. Results showed that goitrin content in cabbage depended on the cooking methods, temperature, and time, while that of Chinese kale only depended on the methods. In contrast, the concentrations of SFN in cabbage and BITC in kale depended on the cooking temperature and time but not methods. Based on RSM analysis, the suggested household cooking methods for preserving isothiocyanates and reducing goitrin are steaming cabbage at 80-100 °C for 4 min and stir-frying Chinese kale at 60-100 °C for 2 min. Such methods may preserve the bioactive compounds while reducing food hazards.

Evaluation of Factors Affecting Thyroid Levels and its Relationship with Salt Iodine to Suggest the Way Forward!

Background:

In India, 42 million people suffer from thyroid diseases. One in 10 adults suffer from hypothyroidism. Although coverage of iodized salt utilization has increased after universal salt iodization, we are yet to achieve the goals of NIDDCP for which the present study was planned to identify the hidden factors. The aim is to identify the factors affecting thyroid hormone levels, their association with salt iodine content and suggest strategies for improvement based on patient perceptions.

Methods:

A hospital based prospective follow up study was conducted among 140 patients, with an in depth interview and testing of salt iodine content. Data were analyzed using the SPSS software.

Results:

96 (69%) patients were of age 18–35 years. 129 (92%) were females, 120 (86%) were from rural areas, 95 (68%) were literate, 116 (83%) were unemployed, and 115 (82%) were of low socioeconomic status. Most of them had poor cooking practices and dietary habits. The T3, T4, and TSH levels were within the normal range in 84 (60%) patients. Only in 28 (20%) salt samples, the iodine content was adequate. The association between factors like intake of inadequately iodized salt (P < 0.01), rural distribution (P < 0.05), illiteracy, presence of the comorbid conditions (P < 0.0001), and thyroid hormone abnormality was found to be statistically significant.

Conclusion:

The factors that adversely affect thyroid levels were higher age, female gender, rural distribution, comorbid conditions and patients with low salt iodine were prone to abnormal levels. Monitoring salt iodine content, training of health care workers to create awareness were the key strategies proposed for improvement.

In vitro metabolic conversion of the organic breakdown products of glucosinolate to goitrogenic thiocyanate anion

BACKGROUND

Glucosinolates are abundant in Brassicaceae vegetables, and they are degraded into various organic breakdown products (BPs) (R-CN, -NCS and -SCN) by myrosinase when plant tissues are damaged. This study was designed to investigate whether these BPs could be broken further into goitrogenic thiocyanate anions (SCN(-) ) metabolically and/or spontaneously. Ten glucosinolates were chosen for this study based on the various structures of their side chains. SCN(-) and cyanide anions (CN(-) ) liberated from the BPs of these glucosinolates were quantified after incubation with human liver S9 and rhodanese.

RESULTS

Upon treatment with metabolic enzymes, CN(-) was produced from all organic thiocyanates, aliphatic and benzyl nitriles, then a substantial amount of produced CN(-) was further metabolized to SCN(-) by rhodanese. All organic thiocyanates and allyl isothiocyanate were metabolized to produce SCN(-), without involving CN(-) production. Spontaneous degradation to SCN(-) in an aqueous environment was observed only in 4-(methylthio)butyl thiocyanate, though the enzymatic reaction rate exceeded the spontaneous one. Among these BPs, the major source of SCN(-) was organic thiocyanates.

CONCLUSION

The results show that some organic nitriles, organic thiocyanates and allyl isothiocyanate may be regarded as potential sources of SCN(-) through metabolism when people ingest glucosinolate-containing vegetables.