Postharvest Application of Thiol Compounds Affects Surface Browning and Antioxidant Activity of Fresh-Cut Potatoes

The aim of this study was to compare the effects of sodium metabisulphite and the thiol compounds, glutathione (GSH), L-cysteine (CYS), and N-acetylcysteine (NAC), on the enzymatic browning, antioxidant activities, total phenolic, and ascorbic acid content of potatoes after 1, 24, and 48 hr. Three different concentrations (0.5%, 1.0%, and 2.0%) of each thiol compound were tested. While sulphite solution inhibited polyphenol oxidase as expected, NAC and CYS also decreased its activity. CYS-treated samples exhibited the highest residual thiol content, while the amount of residual thiol in GSH-treated samples was the lowest. The 2.0% NAC and 2.0% CYS solutions were the most effective at increasing antioxidant activity and ascorbic acid content; however, the results of total phenolic content assays were complicated. In summary, solutions containing 2.0% NAC, 1.0% CYS, and 2.0% CYS prevented enzymatic browning and increased the residual thiol content, ascorbic acid, and antioxidant activities of fresh-cut potatoes significantly, but GSH did not significantly inhibit browning. Practical applications: Fresh-cut potatoes are susceptible to enzymatic browning, which significantly reduces their commercial value. In literature, there have been several methods to protect the enzymatic browning of fruits and vegetables. Among these methods, thiols are good inhibitors of enzymatic browning. So, GSH, CYS, and NAC were used in this study. The outcomes of current work may help to inhibit polyphenol oxidase activity and increase the ascorbic acid content, residual thiol content, and antioxidant activity of fresh-cut potatoes. Both CYS and NAC may be useful alternatives to sulphite anti-browning agents, which may have adverse health effects

Thiols and Their Uses in the Food Industry

Yapılan çalışmalar gıdalara farklı amaçlar doğrultusunda eklenen sentetik katkı maddelerinin_x000D_ birçoğunun insan sağlığını olumsuz yönde etkilediğini ortaya koymaktadır. Bu sebeple,_x000D_ araştırmacılar hem sentetik katkı maddelerinin yerini alabilecek hem de çeşitli fonksiyonları ile_x000D_ sağlığı olumlu etkileyecek doğal katkı maddeleri üzerine yoğunlaşmıştır. Biyotiyoller, gıdalarda_x000D_ renk, tat ve aroma üzerinde etkileri bulunan aynı zamanda antioksidan ve koruyucu etkileriyle_x000D_ oksidatif hasarı engelleyerek kanser, Alzheimer, Parkinson, akciğer ve kalp hastalıklarının_x000D_ önlenmesinde çeşitli fonksiyonlara sahip olan bileşiklerdir. Bu derlemede, gıdaların tiyol içerikleri,_x000D_ fonksiyonları ve gıda sektöründe sentetik katkı maddelerinin yerine kullanım olanakları üzerine_x000D_ yapılmış çalışmalar bir araya getirilmiştir. _x000D_ _x000D_Studies have shown that many of the synthetic additives which are added to food for different_x000D_ purposes have negative impacts on human health. For this reason, researchers have focused on_x000D_ natural additives that can replace with synthetic ones and positively affect health through their_x000D_ various functions. Biothiols have effects on color, taste and aroma in foods. In addition, they possess_x000D_ various functions in the prevention of cancer, Alzheimer's, Parkinson's, lung and heart diseases by_x000D_ decreasing oxidative damage with their antioxidant and protective effects. In this review, the studies_x000D_ about thiol contents of food, their functions and the possibilities of using thiols in the food industry_x000D_ instead of synthetic additives have been brought together

Impact of food disinfection on beneficial biothiol contents in vegetables

In this work we investigated the impact of food disinfection on the beneficial biothiol contents in a suite of vegetables consumed daily, including spinach, green bean, asparagus, cucumber, and red pepper. Four disinfection technologies commonly studied and/or used in food processing and preservation, including hydrogen peroxide, free chlorine, and gaseous- and aqueous-phase ozone, were examined with common dosages and contact times. Results indicate that the common disinfection technologies may result in significant loss of beneficial biothiols in vegetables which are essentially important to human health, For example, as much as 70% of biothiols were lost when spinach was treated with hydrogen peroxide (5.0 wt %) for 30 min. Approximately 48-54% of biothiols were destroyed by free chlorine and gaseous- and aqueous-phase ozone under typical contacting conditions. In red pepper, about 60-71% of reduced glutathione was oxidized by the disinfectants. The potential decrease in biothiols during disinfection was dependent upon the biothiol type, the disinfectant, and the vegetable. The effectiveness of total bacterial inactivation by the four disinfection technologies was concurrently evaluated. Results show that free chlorine is most effective, achieving disinfection efficiencies of greater than 4 log for all study vegetables. This study may provide important information for the food industry to design optimum contacting methods for vegetables to simultaneously achieve sufficient bacterial disinfection while minimizing loss of beneficial biothiols

Effects of hydrogen peroxide treatment on thiol contents in fresh-cut asparagus (Asparagus officinalis) spears

In this work, the impact of hydrogen peroxide (H2O2) was investigated on the thiol content of asparagus. Fresh-cut asparagus was treated with H2O2 at varied oxidant concentrations and contact times. A significant decrease (=0.05) was observed in N-acetylcysteine levels treated with 2.5% H2O2 for 10 min and with 5% H2O2 for 3, 5 and 10 min. Captopril and cysteine levels significantly decreased (=0.05) in all and most treatment conditions, respectively. Glutathione levels only significantly decreased with 2.5% and 5% H2O2 for 10 min treatment. In order to determine whether asparagus undergoes oxidative stress, a well-known oxidative stress indicatorthe glutathione/oxidized glutathione ratiowas calculated. This study showed that the common use of H2O2 as a disinfectant/sterilizer by the food industry could markedly diminish the important biothiols and develop oxidative stress in asparagus, and potentially in other vegetables as well

Oxidative effects of Tartrazine (CAS No. 1934-21-0) and New Coccin (CAS No. 2611-82-7) azo dyes on CHO cells

Color is an indispensible characteristic of food because it makes foods easily recognizable and attractive in our modern society. Numerous food colors have been removed from the national and international lists of "accepted food colors" due to their mutagenic and carcinogenic activities based on a number of toxicity studies that have been conducted since food colors were first identified as carcinogenic by researchers. This study investigated the changes in oxidative stress parameters such as glutathione (GSH), malondialdehyde (MDA), glutathione peroxidase (GPx) activity, and catalase (CAT) activity that occurred when Chinese hamster ovary (CHO) cells were exposed to Tartrazine (CAS No. 1934-21-0) and New Coccin (CAS No. 2611-82-7), commonly-used azo dyes in the food industry. It was found that intracellular GSH significantly decreased, MDA levels increased, and GPx and CAT levels remained the same, (as compared to the control), when CHO cells were exposed to these food colors. Based on our results, Tartrazine and New Coccin food colors can be regarded as toxic. Considering the possible oxidative damage induced by these food colors, due to the depletion of GSH (a cell's major antioxidant), and a significant increase in MDA levels, we strongly believe that the use of these potentially toxic colors in food needs to be reconsidered

Biologically important Thiols in various vegetables and fruits

Biological thiols are important antioxidants, and recent studies showed that their contents vary depending on the groups of foodstuffs. Therefore, we investigated the levels of some biological thiols in various vegetables and fruits by using a sensitive high-performance liquid chromatography (HPLC) technique. Biological thiols measured in some vegetables and fruits include glutathione (L-glutamyl-L-cysteinly glycine, GSH), N-acetylcysteine (NAC), captopril [CAP (C9H15NO3S)], homocysteine (HCYS), cysteine (CYS), and gamma-glutamyl cysteine (GGC). Our results show that biological thiol contents are between 3-349 nM/g wet weight in vegetables and 4-136 nM/g wet weight in fruits. CAP is only found in asparagus (28 nM/g wet weight). Furthermore, none of the biological thiols analyzed were found in cabbages, red grapes, blackberries, apples, and peaches. Therefore, various vegetables and fruits differ significantly in their thiol contents. Oxidation of these important thiols may occur and result in the production of toxic byproducts, if they are exposed to radiation and ozone treatment for sterilization purposes. Further studies should be performed to monitor the levels of these biological thiols

A SEARCH ON HEAVY METAL ACCUMULATION IN SCADS CAUGHT IN THE GULF OF İZMİT AND OFF TEKİRDAG PROVINCE IN THE SEA OF MARMARA

Heavy metals which contaminate water due to ındustrialization cause a great deal of environmental pollution. In addition to that these metals threaten human health by accumulating in organismas which leave in rivers and seas and being used as nutriment.The aim of this resarch is to determine the mercury, lead and cadmium accumulation in scads (Trachurus trachurus ) caught in the Gulf of İzmit and near Tekirdag in the sea of Marmara. The resarch was carried out in April, May and June 1996. Fish sample analysed for mercury, lead and cadmium elements. Heavy metal contents of fish caught in the Gulf of İzmit were all higher than those of caught in Tekirdag . Avarege mercury contents were 0.316 ppm and 0.029 ppm in the Gulf of fishes and Tekirdag fishes respectively. Average lead contents were 0.269 ppm and 0.038 ppm in the Gulf fishes and Tekirdag fishes respectively. Average cadmium contents was 0.061 ppm in the Gulf fishes. No cadmium was determined in Tekirdağ fishes

Biologically important thiols in various organically and conventionally grown vegetables

Biothiols are well-known beneficial antioxidants that protect cells from oxidative damage that potentially leads to cancer and Alzheimer's disease. This study investigated and compared the levels of important biological thiols including glutathione (L-glutamyl-L-Cysteinyl glycine, GSH), N-acetylcysteine (NAC), captopril (CAP), cysteine (CYS), and gamma-glutamyl cysteine (GGC) in a variety of organic versus conventional (industrially-produced) asparagus, spinach, green beans and red peppers, using a sensitive high-performance liquid chromatography (HPLC) technique. Only the contents of CYS, or CYS with NAC, were detected as significantly higher in organic green beans or organic asparagus, respectively. However, conventional spinach contained significantly higher amounts of all investigated thiols than contained the organic spinach. Results also showed that conventional or organic production methods did not significantly affect the contents of CAP, GSH or CYS in asparagus, green beans or red poppers. In conclusion, production methods do not appear to be the only factor affecting the thiol contents in vegetables

Preferences of Turkish people for irradiated, GM or organic foods

Through commercial application, new technologies may improve health, agriculture, farming practices and the quality of foods. However, along with the array of potential benefits are potential risks and uncertainties surrounding the commercial applications of these technologies. In this study, a survey was prepared to receive opinion of Turkish People living in the most populated area of Turkey about irradiated foods, food additives and organic foods and genetically modified foods. Survey questions were asked to 1226 people (626 women and 600 men) in 4 different age groups (1530, 31-45, 46- 60, 61-90 years old). Questions were generally prepared to expose their knowledge and awareness about food additives, organic foods, irradiation, genetically modified foods or hormone residues in foods. Most of them think that consuming food containing some of the food additives can lead to some health problems. The half of the participants did not have knowledge about food irradiation, The results of the current study also indicated that 9% of respondents did not concern for the safety of irradiated foods; however, 69% of them concerned very much. In addition, the present study indicated that only 8% of respondents thought that GM foods were safe, 69% thought that they were little risky, 23% of them thought they were extremely risky for our health. All participants with different age, gender, income level or education level had negative thought about hormone residues in food products. Interestingly, 29 and 18% of them did not have knowledge about organic foods and believed that they can be unhealthy, respectively. In conclusion, the most of the participants, especially 31-45 years old and high income people, were cautious about what they purchase

Impact of Food Disinfection on Beneficial Biothiol Contents in Strawberry

In this study, the impact of four food disinfectants including hydrogen peroxide, free chlorine, and gaseous- and aqueous-phase ozone with industrial doses on the concentration of biothiol compounds gamma-glutamylcysteinylglycine (GSH) and cystein (CYS) in strawberry was investigated for 1, 5, 15, 30, and 60 or 120 min. Additionally, the amount of oxidized glutathione (GSSG) was analyzed for calculation of the GSH/GSSG ratio as an indicator of oxidative stress. After this treatment, thiol contents of strawberry samples were examined using high-performance liquid chromatography (HPLC) technique. According to the results of measurements, free chlorine treatment for only 60 min significantly decreased CYS content in strawberry (p < 0.05). A significant decline in the GSH/GSSG ratio was also observed when H2O2 was applied for all time intervals except for 1 min (p < 0.05). However, aqueous-phase ozone treatment did not significantly affect the thiol levels (p < 0.05). In conclusion, this study may provide optimum disinfection methods for strawberry to minimize loss of beneficial biothiols