Judul: Characterization of Kombucha Fermented Drink Microalgae Spirulina sp. with Different Extraction Methods
Abstrak: Spirulina sp. is a microalga with a protein content of 64-73 %. Kombucha is a fermented beverage that is beneficial for body health. This research aims to determine the effect of extraction methods on the characteristics of kombucha extract made from Spirulina sp. The methods used include cold temperature maceration extraction, freeze-thaw, and hot temperature extraction. The treatments applied are freezing, brewing, and cold processes. Sample extraction undergoes fermentation with SCOBY (Symbiotic Culture of Bacteria and Yeast). The research results indicate that the method influences the pigment content in Spirulina sp. extract. The freezing treatment using the freeze-thaw method yields the highest pigment content in allophycocyanin pigment and total chlorophyll. Kombucha extract from Spirulina sp. is successfully obtained with pH values ranging from 2.5 to 3.8, alcohol content <0 %, and a TPC value of 105-106 CFU/g. The favorability level of kombucha from Spirulina sp. extract is not significantly different.
Keyword: characterization, extraction, fermentation, kombucha, Spirulina sp.

Judul: Sensory Profile and Flavour of Kombucha  Sargassum sp. with Different Types of Sugars and Fermentation Times
Abstrak: Salah satu cara untuk memperbaiki cita rasa yang pada teh Sargassum yaitu dengan dilakukannya proses fermentasi menjadi teh kombucha. Penelitian ini bertujuan untuk menentukan pengaruh lama waktu fermentasi dan jenis gula yang berbeda terhadap profil sensori kombucha Sargassum, serta karakteristik fisiko-kimia dan profil flavour pada perlakuan jenis gula dan lama fermentasi terbaik. Sampel kombucha Sargassum diberikan perlakuan dengan gula yang berbeda (sukrosa, sorbitol, dan steviol) dan lama waktu fermentasi selama 9 hari dengan waktu pengambilan sampel hari ke 0, 3, 5, 7, 9. Karakteristik kombucha Sargassum dapat dilihat dari parameter pH, alkohol, warna, total gula, dan uji sensori. Berdasarkan uji sensori hedonik sampel terbaik kombucha Sargassum yaitu kombucha Sargassum dengan perlakuan gula steviol dan waktu fermentasi selama 3 hari. Profil flavour sensori kombucha Sargassum dapat dilihat dengan pengujian CATA dan GC-MS. Sampel kombucha Sargassum terbaik memiliki profil senyawa volatil dari golongan asam, alkohol, keton, heterosiklik dan lainnya., One way to improve the taste of Sargassum tea is by fermenting it into kombucha tea. This research aims to determine the effect of fermentation time and different types of sugar on the sensory profile of Sargassum kombucha, as well as the physico-chemical characteristics and flavor profile of the best type of sugar and fermentation time. Sargassum kombucha samples were treated with different sugars (sucrose, sorbitol, and steviol) and a long fermentation time of 9 days with sampling times of days 0, 3, 5, 7, 9. The characteristics of kombucha Sargassum can be seen from the parameters of pH, alcohol, color, total sugar, and sensory tests. Based on the hedonic sensory test, the best sample of Sargassum kombucha was Sargassum kombucha with steviol sugar treatment and fermentation time for 3 days. The sensory flavor profile of Sargassum kombucha can be displayed by CATA and GC-MS testing. The best Sargassum kombucha samples had a volatile compound profiles from acids, alcohols, ketones, heterocyclics and other groups.
Keyword: Fermentation, flavour profile, Sargassum kombucha, sensory

Judul: Truncated Stop Loss as a Optimal Solution of Reinsurance Agreement in One-Period Model
Abstrak: Reinsurance is one of risk management efforts of an insurance company, which is called the cedent. Similar with insurance, reinsurance constitutes the cedent to pay the premium. We consider one-period reinsurance model and derive a rule which minimizes the ruin probability of the cedent for a fixed reinsurance premium. Therefore, it is needed to construct an optimal reinsurance agreement for the cedent. The premium is calculated according to four different principles, i.e. economic, generalized zero-utility, Esscher, and mean-variance principles. Stop loss is a reinsurance contract which protect the insurance company for losses that exceed a certain amount. The result of this research shows that a truncated stop loss is an optimal agreement in the class of all reinsurance contracts with various premiums calculated using above mentioned principles.
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