{"id":7735,"date":"2018-11-01T13:53:00","date_gmt":"2018-11-01T11:53:00","guid":{"rendered":"https:\/\/www.torosidis.gr\/?p=7735"},"modified":"2018-11-01T13:53:00","modified_gmt":"2018-11-01T11:53:00","slug":"%ce%bf%cf%83%ce%bc%ce%ae-%cf%85%ce%b4%cf%81%cf%8c%ce%b8%ce%b5%ce%b9%ce%bf%cf%85-%ce%b3%ce%b9%ce%b1%cf%84%ce%af-%ce%bc%cf%85%cf%81%ce%af%ce%b6%ce%b5%ce%b9-%ce%ac%cf%83%cf%87%ce%b7%ce%bc%ce%b1-%cf%84%ce%bf-%ce%ba%cf%81%ce%b1%cf%83%ce%af-%ce%bc%ce%bf%cf%85","status":"publish","type":"post","link":"https:\/\/www.torosidis.gr\/en\/%ce%bf%cf%83%ce%bc%ce%ae-%cf%85%ce%b4%cf%81%cf%8c%ce%b8%ce%b5%ce%b9%ce%bf%cf%85-%ce%b3%ce%b9%ce%b1%cf%84%ce%af-%ce%bc%cf%85%cf%81%ce%af%ce%b6%ce%b5%ce%b9-%ce%ac%cf%83%cf%87%ce%b7%ce%bc%ce%b1-%cf%84%ce%bf-%ce%ba%cf%81%ce%b1%cf%83%ce%af-%ce%bc%ce%bf%cf%85\/","title":{"rendered":"Smell of hydrogen sulfide. Why My Wine Smells Bad."},"content":{"rendered":"

Hydrogen sulfide (H2<\/sub>S) is a thiol of very high volatility with a very low concentration at which the smell of , is perceived which is reminiscent of that spoiled egg. The presence of hydrogen sulfide in must and wine may be due to many causes (Monk 1986). Those related to yeasts and nitrogen are commented on below.<\/p>\n\n\n\n

 \u00b7 It has been adequately documented that hydrogen sulfide is formed metabolically from yeasts either from inorganic sulphur compounds , such as sulphites and sulphates , or from organic sulphur compounds such as cysteine and glutathione (Rankine 1963, Eschenbruch 1974, 1978, Schiitz and Kunkee 1977, Monk 1986, Henschke and Jiranek 1993, Rauhut 1993, Jiranek et al. 1995b, Hallinan et al. 1999, Spiropoulis et al. 2000).<\/p>\n\n\n\n

 Hydrogen sulfide is usually synthesized to meet the increased metabolic needs of yeasts in organic sulfur compounds, such as those that occur during their growth phase.<\/p>\n\n\n\n

* Some , strains, however, appear to form irregular amounts of hydrogen sulfide and probably represent metabolic errors at least for the environment that characterizes wine (Jiranek et al. 2009). 1995b, Spiropoulis et al. 2000).<\/p>\n\n\n\n

The must is usually deficient in organic sulfur compounds (less than 10 mg\/l of cysteine and methionine). * The lack of organic sulphur compounds in must stimulates the synthesis of organic sulphur compounds in , yeasts from inorganic sources which are usually found in surplus in must (Henschke and Jiranek 1991, Hallinan et al. 1999). Thus hydrogen sulfide is an intermediate metabolic product when reducing sulfates or sulphites necessary for the synthesis of organic sulfur compounds (Rauhut 1993).<\/p>\n\n\n\n

\u00b7 When these reactions evolve in the presence of the appropriate amount of , nitrogen, hydrogen sulfide is removed by the formation of organic sulfur compounds (Ono et al. 1999). But under some , conditions when insufficient or inappropriate sources of nitrogen are available , free hydrogen sulfide can accumulate inside the cell and diffuse into the fermented must (Henschke and Jiranek 1991).<\/p>\n\n\n\n

\u00b7 The hydrogen sulfide formed from the beginning to the middle of the alcoholic fermentation of the must is related to the growth of , yeasts and its formation usually responds to the addition of nutritious , in particular diammonium phosphate (Henschke and Jiranek 1991, Jiranek et al. 1995b).<\/p>\n\n\n\n

* The strain of , yeast used; the source of , sulphur; the composition and concentration of nitrogen in the fermented , medium are among the factors influencing the production of hydrogen sulphide (Spiropoulis et al. 2000). \u00b7 Research conducted using different methods shows that yeast strains are highly variable in their ability to produce , hydrogen sulfide, making the yeast strain the most important factor determining hydrogen sulfide production (Rankine 1968a, Eschenbruch et al. 1978, Thornton and Bunker 1989, Thomas et al. 1993, Giudici and Kunkee 1994, Jiranek et al. 1995c, Spiropoulis et al. 2000, Mendes-Ferreira et al. 2002).<\/p>\n\n\n\n

* Laboratory studies have shown that for a strain that responds to nitrogen addition during alcoholic fermentation , the ability of an amino acid to regulate hydrogen sulfide production is related to its effectiveness as a nitrogen source , although there are several notable exceptions (Jiranek et al. 2011). 1995b).<\/p>\n\n\n\n

* As ammoniacs limit the expression of the Met10 , gene which is responsible for the coding of the alpha-subgroup of sulphite reductase (Hansen et al. * 1994), it is not surprising that diammonium phosphate is widely used in practice to control the production of , hydrogen sulfide but is not always effective. <\/p>\n\n\n\n

Henschke and Jiranek (1991) identified a second phase of hydrogen sulfide production related to the final stages of alcoholic fermentation. * In this phase there was practically no response to the addition of diammonium phosphate , although in some cases diammonium phosphate appears to stimulate hydrogen sulfide production when combined with aeration (Thomas et al. 2009). 1993, Henschke and de Kluis 1995). <\/p>\n\n\n\n

Whilst recent research improves our knowledge of sulphur metabolism in , yeasts in particular in the field of , hydrogen sulphide production, the use of selected strains remains the most useful tool for limiting hydrogen sulphide production during winemaking.<\/p>\n\n\n\n

* As the production of hydrogen sulfide during the alcoholic fermentation of the must has many , causes, the measurement of the nitrogen assimilable by the yeasts in the must and the additions of nitrogen (e.g. diammonium phosphate) continue to be the best approach to control in the act of hydrogen sulfide production at the beginning and up to the middle of the alcoholic fermentation. Only when the production of hydrogen sulfide fails to be regulated by the addition of nitrogen should other options be sought.<\/p>\n\n\n\n

Source: Bell S-J and P.A. Henschke , 2005. <\/strong>Implications of nitrogen nutrition for grapes , fermentation and wine. Australian Journal of Grape and Wine Research 11 , 242-295.<\/p>\n\n\n\n

<\/p>\n

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Hydrogen sulfide (H2S) is a very high volatile thiol with a very low concentration at which the odor of ... <\/p>","protected":false},"author":1,"featured_media":7738,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_seopress_titles_title":"","_seopress_titles_desc":"","_seopress_robots_index":"","_seopress_robots_follow":"","_seopress_robots_imageindex":"","_seopress_robots_snippet":"","_seopress_robots_primary_cat":"none","_seopress_robots_breadcrumbs":"","_seopress_robots_freeze_modified_date":"","_seopress_robots_custom_modified_date":"","_seopress_robots_canonical":"","_seopress_social_fb_title":"","_seopress_social_fb_desc":"","_seopress_social_fb_img":"","_seopress_social_fb_img_attachment_id":0,"_seopress_social_fb_img_width":0,"_seopress_social_fb_img_height":0,"_seopress_social_twitter_title":"","_seopress_social_twitter_desc":"","_seopress_social_twitter_img":"","_seopress_social_twitter_img_attachment_id":0,"_seopress_social_twitter_img_width":0,"_seopress_social_twitter_img_height":0,"_seopress_redirections_value":"","_seopress_redirections_enabled":"","_seopress_redirections_enabled_regex":"","_seopress_redirections_logged_status":"both","_seopress_redirections_param":"","_seopress_redirections_type":301,"_seopress_analysis_target_kw":"","footnotes":""},"categories":[38],"tags":[36,37],"class_list":["post-7735","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-wine","tag-36","tag-37","image-hover-transition-effect"],"gutentor_comment":0,"_links":{"self":[{"href":"https:\/\/www.torosidis.gr\/en\/wp-json\/wp\/v2\/posts\/7735","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.torosidis.gr\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.torosidis.gr\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.torosidis.gr\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.torosidis.gr\/en\/wp-json\/wp\/v2\/comments?post=7735"}],"version-history":[{"count":0,"href":"https:\/\/www.torosidis.gr\/en\/wp-json\/wp\/v2\/posts\/7735\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.torosidis.gr\/en\/wp-json\/wp\/v2\/media\/7738"}],"wp:attachment":[{"href":"https:\/\/www.torosidis.gr\/en\/wp-json\/wp\/v2\/media?parent=7735"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.torosidis.gr\/en\/wp-json\/wp\/v2\/categories?post=7735"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.torosidis.gr\/en\/wp-json\/wp\/v2\/tags?post=7735"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}