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Bahan Ajar Teknik Penanganan Hasil Pertanian - Revisi 0 - Update 02 Februari 2010 1

Karakteristik bahan dan produk agroindustri

Oleh :

Sarifah Nurjanah

Teknologi Industri PertanianUniversitas Padjadjaran Bandung

Produk hasil pertanian

Grain

Fruits and vegetables


Fish

Livestocks

Ciri produk pertanian :

n Bulky/ kamba : memakan banyak tempat

n Musiman : tidak selalu ada setiap saat

n Mudah rusak (perishable) : karena masihmerupakan living thing/ makhluk hidup

n Tidak seragam : dalam satu kali panen bisabeberapa ukuran


Bulky/ Kamba

- Ada rongga diantara satu bahan dg yang lain


Musiman

- Buah-buahan : mangga, durian, dll

- Perikanan tangkap

Chilling injury

crownrot Impact bruishing

Mudah rusak

-Physiological factors (environmental factors, which affect product metabolism)

-Physical factors (mechanical damage)

-Biotic factors (pest and disease)


Tidak seragam

-Dalam satu kali panentidak sama tingkatkematangan dan ukuran

-Perlunya sortasi dangrading

Sifat Biologi

nMasih berlangsungnya metabolismesesudah dipanen.

n Terjadinya perubahan komponen dalambahan yang akan menyebabkanberubahnya teksture dan penampakanserta rasa.

n Perubahan yang terjadi mempengaruhimutu produk.


Metabolism

The most important physiological processes :

- Transpiration : through the stomata, is related to cooling, as temperature increases, the rate or transpiration also increases.

-Respiration : involves the uptake of oxygen, the release of carbon dioxide, and the breakdown of stored reserves, provide energy for metabolism , growth and maturation.

A reduction in the rate of transpiration and respiration extends market life and improves overall fruit quality.

Respiration rate indicates:

-Metabolic activity in plant tissue

-Also a guide to the potential storage life of product

C6H12O6 + 6O2 → 6CO2 + 6H2O + energy

Glucose oxygen carbon waterdioxide


Ripening chart

respiration

Perubahan komponen


Climacteric and non climacteric produce


Climacteric :

-Banana

-Avocado

-Mango

-Tomato

-Watermelon

Nonclimacteric :

-Pineapple

-Lemon

-Orange

-Cucumber

-Grape

Dormant produce : Potato

Changes in weight, sugar, etc


Changes in weight, texture, color, sugar content, etc of banana

ripening


Sifat fisik dan mekanik

n Sifat fisik :

- ukuran, bentuk, luas permukaan, volume, densitas, porositas, warna, penampakan.

- sifat yang sangat penting dalammendesain proses dan mesin prosessing

- mempengaruhi tingkat penerimaankonsumen

Physical Characteristics

Shape and Size

- inseparable in a physical object

- generally necessaery if the object is to be satisfactory described

-dimensional parameters of the object must be measured

Charted standards : - round, approching spheroid

- oblate, flattened at the stem end and apex, etc

Roundness

Sphericity


Menentukan kebundaran

(roundness)

Roundness = Ap

Ac

Ap = Lingkaran terdalam

Ac = Lingkaran terluar

Roundness

Spericity

1/3

Spericity =

= =

= =

where a = longest intercept

b = longest intercept normal to a

c = longest intercept normal to a and b

( )sphere edcircumscib of volume solid of volume

( ) 3/1

/6)a(

/6)abc(3π

π ( ) 3/1

a

bc2

diametermajor

diametermean geometric

a

abc)( 1/3


•Volume dan luas permukaan

a. bulat memanjang

V = 4/3 (π ab2) V = volume

S = luas permukaan

S = 2 π b2 + 2 π ab sin –1 e a = poros memanjang elip (major axes)

. e b = poros membujur elip (minor axes)

e = eksentrisitas yaitu

e = [ 1 – (b/a)2 ] 1/2b. bulat membujur

V = 4/3 (π a2b)

S = 2πa2 + π b2 log e 1 + e

. e 1 – e

c. bentuk kerucut

V = (π/3) h (r12 + r1r2 + r22) r1 = jari-jari bagian dasar kerucut

r2 = jari-jari bagian puncak kericut

S = π (r1 + r2) [h2 + (r1 – r2)2]1/2 h = tinggi benda

Density

Density = weight of material, kgvolume of the material,m3

The density values of grains and other commodities are used in design of storage bins and silos, separation of desirable materials from impurities, cleaning and grading, evaluation of the grain etc.


• Sifat thermalImportance:

Thermo-physical properties are important for process calculations during heat and mass transfer, process optimization and modeling. Predicting the shelf life of food products during storage and distribution

These properties change with the type of product, product composition, product temperature, and the direction of heat flow. Specific heat and thermal conductivity are the most important thermal properties required in calculating heat transfer.


Thermo-physical properties of interest

Specific heat Thermal conductivityThermal diffusivity

Specific heat

-The amount of heat in kilocalories that must be added to or removed from 1 kg of a substance to change its temperature by 1oC

-The unit is K cal/kgoC

Thermal Conductivity

Thermal conductivity is a property of a material. It can be defined as the rate of heat that will be conducted through a unit thickness of a material when a unit temperature gradient exists across that thickness. The unit of thermal conductivity is W/m-°C.

Thermal Diffusivity

The rate at which heat diffuses by conduction through a material depends upon the thermal diffusivity of the material. The unit of thermal diffusivity of material is m2/sk.

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