PERILAKU REOLOGI DAN KOEFISIEN PEMBASAHAN LARUTAN PELAPIS BERBASIS KITOSAN PADA PERMUKAAN KULIT BUAH PISANG (Musa acuminata colla)

JHONNI SIGIRO, Sri Rahayoe, STP.,MP.

2014 | Skripsi | TEKNIK PERTANIAN

Penanganan pascapanen produk hortikultura seperti buah pisang masih perlu ditingkatkan dalam rangka memperpanjang umur simpan buah. Salah satu upaya pascapanen adalah pelapisan buah pisang menggunakan kitosan dengan tujuan film pelapis dapat menghambat respirasi buah. Keberhasilan fungsi pelapisan ditentukan oleh karakteristik larutan pelapis, sehingga pada penelitian ini dikaji perilaku reologi dan koefisien pembasahan larutan pelapis berbasis kitosan pada permukaan kulit buah pisang. Kitosan dilarutkan dalam asam asetat 1% dengan konsentrasi kitosan 1% dan 0,5%. Larutan kitosan 0,5% dan 1% masing-masing ditambahkan aditif dengan konsentrasi yang bervariasi yaitu NaCl 0,1M – 0,5M, gliserol 0,1% - 0,5% (w/w), tween 0,02% - 0,1% (w/w). Larutan pelapis kitosan yang telah ditambahkan NaCl dan gliserol diukur viskositasnya dengan menggunakan viskometer Brookfield, kemudian ditambahkan tween dan diukur tegangan permukaannya. Larutan pelapis yang terpilih diukur sudut kontaknya terhadap permukaan kulit buah pisang menggunakan digital microscope. Hasil penelitian menunjukkan penambahan kekuatan ionik dan plasticizer dapat menurunkan viskositas larutan pelapis kitosan. Nilai flow indeks semua larutan lebih dari 1. Tegangan permukaan larutan pelapis kitosan berkisar 32 – 49 mN/m, sudut kontak larutan terhadap permukaan kulit buah pisang berkisar 43 – 86 radius, dan koefisien pembasahan (wettability) bernilai -26,785 sampai – 8,935. Hasil analisis statistik menunjukkan bahwa penambahan aditif padal larutan pelapis kitosan tidak mempengaruhi nilai flow indeks, namun berpengaruh signifikan terhadap nilai sudut kontak dan tegangan permukaan sehingga berpengaruh terhadap nilai wettability. Larutan kitosan terbaik untuk pelapisan buah pisang memiliki wettability mendekati nol adalah konsentrasi kitosan 1% dengan penambahan NaCl 0,3M gliserol 0,8%, dan surfaktan sebanyak 0,08%

The postharvest development of banana is still need to be improved in efforts to increase the banana’s self life. One method that usually used to extend the self life of banana is coating method using chitosan film. The evectivenes of chitosan film that used to coat fruit is affected by the characteristics of chitosan solution. The objective of this research was to evaluate reological behaviour of chitosan solution and its wettabilty coeffisient when aplied on the banana skin surface. .This research was conducted by dissolve chitosan using 1% of acetate acid to obtaining the 1% and 0.5% of Chitosan solvent. 0,1M - 0,5M concentration of NaCl, 0.1% - 0.5% of glycerol (w/w), 0.02% - 0.1% of tween (w/w) were added to the 1% and 0.5% of Chitosan solvent. The rheological behaviour of the chitosan solvent was determined by its flow index, and the wettability coeffisient was evaluated by determining the solvent surface stress and angle of contact. The research result showed that the addition of NaCl and glyserol decreased solvent viscosity. The Flow Index value of the solvents is bigger than 1 and chareacterized as a dilatant and non Newtonian solution. The chitosan film solvent surface stress is valued between 32 – 49 mN/m, the solvent contact angle to banana surface skin is valued between 43 – 86 radiance, and the wettability coefficient is valued between -26,785 to -8,935. The statistical analysis result showed that the addition of addictive to the chitosan film solvent did not affect the flow index, but showed significantly effect to the contact angle and the surface stress value that effecting to the coeffisient of wettabilit. The best chitosan film solvent covering banana skin that having the wettability value approach to 0 is 1 % of chitosan with the 0.3M of NaCl, 0.8% of glycerol, and 0.08% of surfactant addition.

Kata Kunci : Pisang, kitosan, flow indeks, wettability, aditif