Thesis

Effects of Pregelatinization Using Drum Dryer on Physical and Pasting Properties of Three Different Pigmented Rice Varieties

---

A more dynamic life with increased awareness of health and nutrition awareness has urged the
innovation of nutritious food products. Pigmented rice (Oryza sativa L.) has caught the public's
attention and is suggested to be used to create specialty food products due to its availability and
superior nutrients. To expand its utilization, drum drying, the most economical and easiest
pregelatinization method, is commonly used to modify the physical and functional properties of
starch-based food products. Thus, to understand the effect of drum drying on various products, the
physical and pasting properties of the pigmented rice (red, brown and purple rice) before and after
drum drying were investigated in this study. Each pigmented rice was boiled with water (1:15) for
two hours while the unheated pigmented rice was ground to be used as the before processing the
sample. The boiled rice was processed with a drum dryer with drum surface initial temperature,
drum speed and internal drum pressure of 120 °C, 5 RPM and 50 psi respectively. The color was then
measured using a UV-VIS spectrophotometer whereas the bulk density, tapped density, flowability
and cohesiveness was calculated manually. Meanwhile the pasting properties were analyzed utilizing
rapid visco analyzer. From the result, each raw pigmented rice has a significantly different color due
to varying amounts of anthocyanin and proanthocyanidins, whereas, BD, TD, flowability,
cohesiveness values were different because of the dietary fiber and carbohydrate content.
Meanwhile, the diverse amount of pasting properties occurred due to the amylose and amylopectin
content. Moreover, the results also showed that drum drying process decreased the L* value while
increased the a* and b* values of the rice. Such changes appeared because of the heat treatment
that breaks down the anthocyanin and non-enzymatic browning. In addition, the drum dried
products exhibited lower bulk density and tapped density with higher flowability and cohesiveness
compared to the before processing sample. It occurred due to the increase of moisture evaporation
rates that enhances the porosity. The rapid visco analysis indicated that the peak viscosity,
breakdown, final viscosity, setback, peak time and pasting temperature of pigmented rice pastes
were significantly decreased after the drying process. The decrease happened because of the
granules disruption due to heat treatments. These can be concluded that the drum drying process
affected the physical and pasting properties of each pigmented rice product similarly.

---

Availability

Detail Information

Series Title

-

Call Number

FT 22-008

Publisher

i3L, Jakarta : i3L, Jakarta., 2022

Collation

-

Language

English

ISBN/ISSN

-

Classification

NONE

Content Type

-

Media Type

-

Carrier Type

-

Edition

-

Subject(s)

physical properties
Drum drying
heat treatment
pigmented rice
pasting properties

Specific Detail Info

-

Statement of Responsibility

-

Other version/related

File Attachment

Comments

---

You must be logged in to post a comment