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49 Journal of Rice Research 2017, Vol 10 No. 1
Introduction
Rice (Oryza Sativa L.) is one of the most popular and
important cereal crops. It is the staple food of more than
three billion people (Bhattacharjee et al., 2002) in 39
countries,that comprises of nearly half of the world’s
population. Commercially more than two thousand
varieties of rice are grown throughout the world. Over 2
billion people in Asia derive 80% of their energy needs
from rice, which contains 80% carbohydrates, 7–8% crude
protein, 3% crude fat, and 3% crude fiber (Juliano, 1985).
Champagne et al., (2006) stated that rice is mainly composed
of starch. Vandeputte et al., (2004) mentioned rice starch
as the major constituent of rice grain. Moldenhauer et al.,
(2006) added that the same level of starch is the base of
determining the quality that the cooked rice would depict.
Rice is widely consumed as white rice in milled and
parboiled form. There are many special cultivars of rice
that contain colour pigments, such as black rice, red rice
and brown rice. Their name refer to the kernel colour
(black, red or purple) which is formed by deposition of
anthocyanin in different layers of the pericarp, seed coat
and aleurone (Chaudhary et al,. 2001). The origin of
coloured rice is as old as rice itself. Rice with a red bran
layer is called red rice. Though, the colour is confined to the
bran layer, a tinge of red remains even after a high degree
of milling. Unmilled rice has a higher nutrient content than
milled or polished white rice. Red rice contains 7g/100g
protein, 5.5mg/100g iron, 3.3mg/100g zinc, and 2g/100g
fibre respectively. Red rice has a nutritional value more
than that of milled and or polished rice FAO (2004).
Rice was known to the civilization 5000 BC. However
the Chinese, Southern and East Asians are believed to
have learnt the practice of growing rice around 2000 BC
(Chaudhary et al., 2001).
De candolle (1886) and Watt (1892) believed that rice
was originally cultivated in South India. India is one of
the rice producing country with larger area involved in
the cultivation of rice. Historians believe that the well-
known variety of rice was first domesticated in the area
covering the foothills of the Eastern Himalayas. Rice
seems to have appeared around 1400 BC in southern
India after its domestication in the northern plains. Some
say that the word rice is derived from the Tamil word
“Arisi” (Hiziroglu et al., 2007). The rice crop forms the
basic economic activity directly or indirectly for about 150
million rural households in India (Krishnaiah et al., 2000).
ORIGINAL RESEARCH ARTICLE OPEN ACCESS
Qualitative Characteristics of Red Rice and White Rice Procured from Local Market
of Uttarakhand: A Comparative Study
Rita singh Raghuvanshi, Anuradha Dutta*, Gunjan Tewari and Shweta Suri
Department of Foods and Nutrition, College of Home Science, G.B. Pant University of Agriculture and Technology,
Pantnagar- 263145 (U.S. Nagar), Uttarakhand, India
*Corresponding author - adutta.gbpuat@gmail.com
Received: 4th April, 2017 Accepted: 5th May, 2017
Abstract
The present study was undertaken with the objective to evaluate and compare the physical characteristics, nutritional
quality, antioxidant properties and glycemic index of indigenously grown raw red rice grown in Udham Singh Nagar
district of Uttarakhand and white rice (Sarbati) procured from local market of Uttarakhand, India. Of the thirteen
physical quality parameters evaluated, red rice proved to be superior to white rice in all parameters barring seed
length. Red rice was found to have a higher iron, magnesium, calcium, and zinc content than white rice. Regarding
other nutrients the study revealed that red rice has a higher crude protein (10.49%) and crude fiber (2.71%) content
as compared to white rice. The nutritional quality of red rice was found to be comparable to many millets, fruits and
vegetables. It showed excellent antioxidant properties too such as total phenolic content (143.38 mg GAE/100g of
phenol), total flavonoid content (120.0 mg R.E. /100 gm of flavonoid) and DPPH scavenging activity (25 per cent).
Red rice was found to have a lower glycemic index (63.15 ± 2.63mg/dl) than white rice due to which it can be a part
of the diets of diabetics as well as persons suffering from other non-communicable diseases. Red rice is a storehouse
of nutritional excellence and is a healthier alternative to white or polished rice.
Keywords: Red rice, Antioxidants, Glycemic index, Nutritional composition, Physico-chemical characteristics.
Abbreviations: DPPH:2, 2 Diphenyl 2 picryl hydrazyl hydrate;TFC:Total flavonoid content; TPC:Total phenol content;
R.E:Retinol equivalent; GAE:Gallic acid equivalent
50 Journal of Rice Research 2017, Vol 10 No. 1
Ancient Indian literature Charaka Samhita, authored by
great Charaka mentioned rice with red husk and grain as the
best which is efficacious and subdues the diseases (Kumar,
1988; Krishnamurthy, 1991). Eaten as a whole grain, Red
rice is commonly consumed in Himachal Pradesh, Uttar
Pradesh and South India, especially Karnataka and Tamil
Nadu and is predominantly known for its aroma and taste.
But rice consumers often prefer to have polished white rice
despite the valuable food content of coloured rice which is
lost when bran is removed while polishing.
The choice of carbohydrate-rich foods in the habitual
diet should take into account not only their chemical
composition but also their ability to influence postprandial
glycemia (glycemic index) (Riccardi et al., 2008).
Polyphenol and flavonoid which have antioxidant capacity
present in many foods and vegetables are regarded
as the functional materials. Regular intake of these
phytochemicals can reduce many chronic diseases such as
cardiovascular diseases, heart diseases, diabetes, obesity
and certain cancers, and improve endothelial function and
reduce blood pressure (Liu, 2007; Yawadio et al., 2007;
Jonathan et al., 2006).
Little or no information is available on nutritive value of
red rice grown in tarai region of Uttarakhand. Therefore,
the study is aimed to estimate and analyse the physical
characteristics, nutritional quality, antioxidant properties
and glycemic index of white rice and red rice.
Materials and Methods:
Procurement of sample: Samples of two types of rice
(Oryza Sativa L.) viz. indigenously grown raw red rice from
Udham Singh Nagar district of Uttarakhand, and white rice
(Sarbati) were procured from Uttarakhand Agricultural
Production Board and the local market respectively.
Estimation of nutritional quality: Dehusked red rice
and milled, polished white rice samples were analysed
in triplicate for proximate composition such as percent
moisture, crude protein, total ash, crude fat and crude
fibre. Proximate composition was determined by the
method given by AOAC (2000). The carbohydrate
percentage was determined by the difference method as
reported by (Onyeike et al., 1995). The calorific value
(Kcal/100g) of sample was calculated by summing up the
product of multiplication of per cent crude protein, crude
fat and carbohydrate present in the sample by 4, 9 and 4
respectively.
Minerals: Calcium, iron, zinc, and magnesium in
the sample were estimated using atomic absorption
spectrophotometer. Ash solutions were prepared using wet-
ashing procedure as described by Raghuramulu (2003).
Physical properties: The physical properties of white
rice and red rice such as Seed volume, seed weight, seed
density, hydration capacity, swelling capacity, length of
grains, bulk density, and kernel elongation were estimated
by the procedure reported by (Williams et al., 1983). Alkali
spread value was calculated by method described by (Little
et al., 1958) and the kernel elongation was calculated as
described by (Azeez et al., 1966).
The hydration capacity of the grain is an important attribute
which affects the cooking quality and in turn organoleptic
qualities of product Potty (1996). The author also reported
that large sized particles have low bulk density; progressive
size reduction increases the bulk density significantly.
Cooking quality: Different grain samples take different
time for cooking therefore the rice samples were soaked
for a constant period of 60 minutes and cooked for 3
different timing viz. 20, 30 and 40minutes. The number of
cooked grains were counted and put in 500ml of boiling
water and timed from the time the water started boiling
again. After specified period remaining water was drained
off and the softness of the grain was gauged manually by
pressing them between the thumb and index finger. The
cooked grains were counted and recorded in percentage.
Antioxidant properties: Total flavonoid content (TFC),
total phenol content (TPC) and DPPH scavenging activity
were determined.
Total flavonoid content - Total flavanoid content was
determined according to the method given by Zhishen et
al., (1999).
Total Phenol content: The Total Phenol content was
determined according to the method given by Singleton et
al., (1999) using Folin- ciocalteu reagent.
DPPH scavenging activity: The total antioxidant activity
was determined according to the method given by Brand et
al., (1995) using 1,1- diphenyl-2-picryl hydrazyl (DPPH).
Glycemic Index: The glycemic index of white rice and
red rice was determined using the procedure described by
(Brouns et al., 2005).
Statistical Analysis: The data obtained on the proximate
composition, mineral content, physical properties and
antioxidant content of white and red rice were further
analysed statistically. Mean ± S.D. was calculated for
chemical composition of white and red rice.
Results and discussion
Nutritional composition of white rice and red rice:
The results of proximate composition and minerals are
presented in Table 1. White rice was found to have 12.7%
moisture, 7.6% crude protein, 0.46% ash, 0.62% fat, 0.23%
fibre, and 78.34% carbohydrate. On the other hand, red rice
was found to have 12.75% moisture, 10.49% crude protein,
1.53% ash, 1.815 fat, 2.7% fibre and 70.19% carbohydrate
content. The protein content of red rice is comparable to
other cereals and millets such as Whole wheat (11.8%),
51 Journal of Rice Research 2017, Vol 10 No. 1
Barley (11.5%), Bajra (11.6%) and Jowar(10.4%). The ash
content of Red Rice was higher than that of White Rice.
Red rice is a rich source of fibre as compared to whole
wheat (1.2%), Bajra (1.2%) and many vegetables such as
amaranth, spinach, cucumber and carrot (Gopalan et al.,
2007). The total physiological energy was recorded as
349.34 kcal in white rice and 341.29 kcal in red rice.
Red rice was found to be a rich mineral source. It had
13.45mg iron, 192.27 mg magnesium, 8.71 mg calcium,
and 1.91 mg zinc while white rice was found to have
7.65 mg iron, 46.45 mg magnesium, 7.94 mg calcium
and 1.49 mg zinc. Red rice has an iron content more
than whole wheat (5.3mg) (Gopalan et al., 2007). Thus,
it can be recommended for the people suffering with iron
deficiency as rice forms a major part of the diet. A high
magnesium content in red rice seeks its importance in the
diet of individuals suffering with various heart disorders,
especially those related to elevated cholesterol level and
hypertension.
Physical properties of white rice and red rice: The
Physical properties of red rice are presented in table 1
compared to white rice sample. Red rice was found to
have a higher 1000 kernel weight (18.3g), seed weight
(1.827g), seed density (1.59 g/ml), seed volume (1.1 ml),
hydration capacity(0.347 g/100 seeds), hydration index
(0.19), swelling capacity (1.6 ml/100 seeds), swelling
index (1.41), kernel elongation (1.32 cm) and bulk density
(0.82 gm/l). Also it has a high gelatinization temperature
and cooking time. However, the length of the red rice grain
is less than white rice. The physical properties of red rice
suggest that it has more density than the white rice.
Table 1. Proximate composition and physical properties
of white rice and red rice
Nutritional
parameters White rice Red rice
Moisture Content
(g/100 gram) 12.75±0.15 12.7±0.13
Crude Fat Content
(g/100 gram) 0.62±0.015 1.81±0.011
Crude Fiber Content
(g/100 gram) 0.23±0.02 2.71±0.1
Crude Protein
Content (g/100 gram) 7.6±0.23 10.49±0.43
Total Ash Content
(g/100 gram) 0.46±0.04 1.53±0.01
Carbohydrate
Content (g/100 gram) 78.34±1.5 70.19±1.0
Energy Content
(kcal/100 gram) 349.34±2.5 341±1.2
Thousand kernel
weight (g) 14.2±0.51 18.3±0.83
Seed weight (g) 1.42±0.02 1.827±0.02
Seed volume (ml) 1.16±0.05 1.1±0.05
Seed density (g/ml) 1.22±0.072 1.59±0.083
Hydration capacity
(g/100 seeds) 0.179±0.03 0.347±0.02
Hydration index 0.125±0.02 0.19±0.009
Swelling capacity
(ml/100seeds) 0.85±0.35 1.6±0.1
Swelling index 0.72±0.34 1.41±0.11
Length of grain(cm) 0.7±0.1 0.56±0.057
Bulk density of 1g of
sample(g/l) 0.703± 0.005 0.82±0.017
Kernel elongation
1.28 cm± 0.127
1.32cm± 0.096
Gelatinization Temp
(Alkali spread value) 1-5scale point High (1-2 scale
point)
Cooking quality 30- 40 min more than 60
min
Antioxidant property of white rice and red rice: The
results of antioxidant properties are presented in Table 2.
The total phenolic content and total flavonoids content
of red rice was found to be 143.38 mg GAE/100 gm and
120 mg R.E./100 gm respectively. The DPPH scavenging
activity was found to be 25%. Sompong et al., (2011) found
the total phenolic content of ten red rice varieties ranging
between 79.2 and 691.4 mg FA equivalent/ 100 gm. Shen
et al., (2009) recorded 147.2 mg RE/100 gm as the mean
flavonoid content of red rice varieties. On the other hand,
the total phenol and flavonoids content of white rice
was found to be 24.26 mg GAE/100 gm and 166.23 mg
R.E./100 gm. The DPPH scavenging activity was found to
be 20%. Yafang et al., (2011) found the phenolic content
of white rice to be ranging between 42.57 mg GAE/100
g to 100.7 mg GAE/100 g and flavonoid content ranged
between 62.1 mg RE/100 g to 182.6 mg RE/100 g.
Table 2. Mineral and Antioxidant properties of white
rice and red rice
II. Minerals and
Antioxidant properties White rice Red rice
Calcium Content (mg/100g) 7.94±0.17 8.71±0.65
Iron Content(mg/100g) 7.65±0.22 13.45±0.60
Magnesium Content
(mg/100g) 46.45±0.649 192.27±5.98
Zinc content(mg/100g) 1.49±0.039 1.91±0.036
Total avonoid content
(mg R.E./100 gm of avonoid)
166.23±0.25 120.0 ±0.38
52 Journal of Rice Research 2017, Vol 10 No. 1
Total phenolic content
(mg GAE/100g of phenol) 24.26±1.05 143.38 ±1.5
DPPH scavenging activity% 20% 25%
Figure 1. Blood glucose response curve for White and Red rice
Glycemic Index: The glycemic index of white rice
and red rice was recorded as 71.7±0.91 and 63.15±2.63
respectively. White rice has 8 per cent more carbohydrate
and 2.5 per cent less crude fibre relatively. Fiber rich
foods like red rice generally have a low glycemic index
(GI) (Radulian et al., 2009). As red rice is relatively rich
in crude fibre, it may be eaten in small quantities by the
diabetic individuals and incorporated in daily diet by the
healthy people too.
Conclusion
In the present study it was found that red rice has a
higher content of crude fiber, crude protein, minerals
and antioxidants than white rice. It has a higher nutrient
density and lower glycemic index which makes it
comparatively superior than white rice. Red rice has
multifaceted nutritional values which make it a highly
beneficial superfood. However, red rice has been relegated
from plates and fields due to the emergence of white rice
as a predominant staple food since the advent of green
revolution. Although the scientific community is totally
aware of its wonders as a source of minerals, protein and
antioxidants, yet alone they cannot make a significant
mark without an immense market demand. The red rice
must evolve onto its journey as a gift of nature rather than
ending as weedy and wild rice. Looking onto its health
properties, it will be desirable to have processed food items
such as puffed and flaked rice, coloured noodles and snack
items prepared from red rice adding to its popularisation
and commercialisation as an important food grain.
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