The yeast, Saccharomyces cerevisiae, is the protagonist in brewing, while spent brewer yeast is a by-product of beer production. Khamr or intoxicant, and its by-product, are prohibited by Shariah, whereas yeast is used to produce alcoholic beverages. Generally, the yeast dies after alcohol fermentation, but some of them settle at the bottom of the fermentation tank. Concerns arise about whether post-purification of spent brewer yeast will take place as it is initially considered impure (najs) because alcoholic fermentation occurs in yeast cytosol. This study examined spent brewer yeast’s halal status, investigated the formation of spent brewer yeast, and analyzed methods of legal ruling on spent brewer yeast according to Shariah and science perspectives. Qualitative approaches had been applied including library research, fiqh adaptation (al-takyif al-fiqhi), and content analysis. Istihalah (transformation), debittering, and decolourization have been proposed for purification. Study shows that spent brewer yeast colour changed from chocolate brown to cream-white after purification, but there is still no complete removal of bitterness from beer achieved. The study concludes that spent brewer yeast can be permissible (halal) for consumption if the colour, odour, and taste of the beer are completely purified from the spent brewer yeast.

Synthetic biology, or SynBio, is a fast-growing technology, that combines biology, chemistry, computer science, and engineering, producing synthetically modified organisms (SMOs), in which organisms for which a large part or the entire genome has been designed using computer-aided design tool and chemically synthesized. Concern arises when (deoxyribonucleic acid) DNA constructs are made up of impure (najs) substances in Shariah as raw material, like transfer of engineered pig cells with modified genomes. One of alternative verification methods of Shariah law, namely al-Intiqal (the transition), can assist Muslim jurists in determining legal rulings on particular Halal contemporary issues, as there is no explicit information about genetic modified technology in the Qur’an or Hadith. This study aims to determine the theory of al-Intiqal (the transition) from Shariah and science approaches and apply the structure and division of al-Intiqal (the transition) on SMOs productions, like synthetic spider silk and humanized pig organ. Qualitative methods were applied including library research, fiqh adaptation (al-takyif al-fiqhi), and semi structured in-depth interview. Study shows that two divisions of al-Intiqal (the transition) can be applied within SMOs productions, which are al-Intiqal al-sahih (the accepted transition) and al-Intiqal al-fasid (the damaged transition). Study concludes that DNA synthesizer as conversion agent within SMOs production process can be considered permissible (Halal), while synthetic spider silk is also permissible (Halal) as the raw material is considered pure and its transition process had completely occurred in Shariah, nonetheless humanized pig organ is impermissible (Haram) as the raw material and its recipient organism are impermissible (Haram) and its transition process had not completely occurred in Shariah, except for emergency (darurah) case with some provisions.