ANALISIS KADAR ALKOHOL METODE OKSIDASI DIKROMAT DALAM SUASANA ASAM

Tujuan                         : Menentukan kadar alcohol dalam bahan pangan.

Prinsip                         : Reaksi oksidasi dikromat oleh alcohol dalam suasana asam.

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PHYTOCHEMICAL TESTING OF PLANTS

TEST TUBE SPOT TEST

                Culvenor and Fitzgerald have described a simple kit that can be taken into the field for use in testing samples of plant material for alkaloids. About 2-4 g of fresh plant part is ground in a small mortar with sand and sufficient chloroform/dichloromethane to make slurry. Ammoniacal chloroform/dichloromethane is added and the mixture stirred for 1 min, prior to filtration into a small test tube. Extraction of the alkaloids from chloroform/dichloromethane is accomplished by shaking the solution with 0.5 mL of 2N sulfuric acid and separation of the acid layer by means of a medicine dropper. A few drops of this extract are the tested with Mayer’s reagents and other reagents to ascertain the presence of alkaloids.

DETECTION OF SAFONINS

                Saponins has several characteristic properties that can be used as a basic for simple detection test. (a) They are capable of hemolyzing red blood cells, (b) in aqueous media they will produce a characteristic honeycomb froth which persists for at least 30 min after vigorous shaking of the solution and, (c) they produce characteristic  color reaction is the Liebermann-Burchard test.

                The appearance of the characteristic  honeycomb froth which persists for at least 30 min after shaking an aqueous boiled (3-5 min) mixture containing the plant material is evidence for the presence of saponins. If only a  small froth is produced by this treatment, which is stable for only a few minutes, proteins, certain plant acids, or a low concentration of saponin may be the cause. This does not distinguish between steroidal and triterpenoid saponins.

                The  Liebermann-Burchard test may be used to detect the the presence of steroids and triterpenes. The following procedure has been used to detect saponins and/or free triterpenes or steroids: the finally ground sample (5-20 g) is extracted with boiling ethanol and the filtered extract is evaporated to drynees. The material obtained is triturated with ether. The residue (ether insoluble material) is subjected to froth and Liebermann-Burchard tests. If the froth test is positive, the ether insoluble material is hydrolyzed with aqueous hydrochloride acid 2N and any precipitate noted. The formation of a precipitate confirms the presence of saponin. The ethereal extract is evaporated to drynees and the residue is subjected to a Liebermann-Burchard test (L.B. test).

LIEBERMANN-BURCHARD TEST    

                A small amount of the material to be tested is placed on a white title and a few drops of acetic anhydride are added and the strirred with a glass rod. A few drops concentrated sulfuric acid are now added and the colors produced are noted. Triterpenoids generally give red, pink, or purple colors which are more persistent than the blues or greens usually obtained from steroids.

QUESTIONS

1.       Did a L.B. test can use for general terpenoid such as  monoterpenoid, sesquiterpenoid, and polyterpenoid, explain briefly!

2.       Define the reaction mechanism of triterpenoid and reagen L.B.!

3.       How we can examined the alkaloids in a part of plant, explain two types of reagent that available for this test!

4.       How to make reagent for detection of alkaloids?

5.       Mention the various alkaloids that mostly present in the plants!

6.       Why presipitant is the indicator the present of alkaloids ?

7.       How we distinguish between steroidal and terpenoid with L.B. reagent and define the mechanism reaction involved!

8.       How to detect saponins in the part of plant?

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Prostaglandin

1)   Apa perbedaan dari PGE dan PGF ?

Jawab :

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Karbohidrat

PEMBAHASAN

            Karbohidrat banyak terdapat dalam bahan nabati, baik berupa gula sederhana, heksosa, maupun karbohidrat dengan berat molekul yang tinggi sperti pati, pektin, selulosa, dan lignin. Selulosa dan lignin berperan sebagai penyusun dinding sel tanaman. Berbagai polisakarida termasuk pati, banyak terdapat dalam serelia dan umbi-umbian, selulosa dan pektin banyak terdapat dalam buah-buahan. (Winarno, 1992)

Pengujian karbohidrat dilakukan dengan beberapa cara, salah satunya adalah pengujian sifat-sifat karbohidrat.

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Air Dalam Sistem Pangan

PEMBAHASAN

            Menurut Winarno, 1992, Kandungan air dalam bahan makanan mempengaruhi daya tahan bahan makanan terhadap serangan mikroba yang dinyatakan dengan a_w, yaitu jumlah air bebas yang dapat digunakan oleh mikroorganisme untuk pertumbuhannya. Hubungan antara a_w dengan kandungan air per gram suatu bahan makanan dapat digambarkan dalam sebuah grafik isoterm sorpsi air.

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Lemak

BAB V

HASIL DAN PEMBAHASAN

1.      Warna dan Aroma Berbagai Minyak dan Lemak

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HACCP (Hazard Analysis Critical Control Point)

Pengertian  (HACCP)

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UAS KIMIA ORGANIK II

1.      Suatu keton di bawah ini dibuat dalam tiga langkah berurut dari senyawa etil trifluoroasetat. Langkah pertama adalah mereaksikan etil trifluoroasetat dengan amonia untuk membentuk senyawa A. Senyawa A dikonversi ke keton yang diinginkan dengan cara pembentukan senyawa B dahulu. Isi reagen yang dibutuhkan dan berikan struktur senyawa A dan B.

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Kimia Pangan

Pengertian  (HACCP)

        HACCP kepanjangan dari “Hazard Analysis Critical Control Point” atau Analisis Bahaya Pada Titik Pengendalian Kritis (ABTKK),  yaitu sebuah pendekatan sistematis untuk mengidentifikasi bahaya-bahaya, tindakan-tindakan pengendalian dalam proses persiapan makanan dimana pengendalian adalah bagian penting dalam memastikan keamanan makanan.

Apabila kita mengetahui faktor-faktor yang mempengaruhi aktifitas mikroorganisme, kita dapat memperkirakan kapan bahaya dapat muncul dan juga mencegah atau mengendalikan bahaya tersebut. Hal inilah yang menjadi dasar pemikiran dari HACCP untuk menciptakan keamanan pada persiapan makanan yang pertmama kali dikembangkan oleh NASA (American National Air and Space Administration)

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