Effect of Heat Treatment and Mineral and Vitamin Supplementation on the Nutritive Use of Protein and Calcium From Lentils (Lens culinaris M.) in Growing Rats

BASIC NUTRITIONAL INVESTIGATION
Effect of Heat Treatment and Mineral and Vitamin
Supplementation on the Nutritive Use of Protein
and Calcium From Lentils (Lens culinaris M.) in
Growing Rats
Jesu´s M. Porres, PhD, Mar?´a Lo´pez-Jurado, PhD, Pilar Aranda, PhD, and Gloria Urbano, PhD
From the Departamento de Fisiolog?´a, Facultad de Farmacia. Instituto de Nutricio´n y
Tecnolog?´a de Alimentos, Universidad de Granada, Granada, Spain
OBJECTIVE: The effects of heat treatment, supplementation of a mineral and vitamin premix, and 4% olive
oil on the bioavailability of protein and calcium from Lens culinaris M., var vulgaris, cultivar. magda-20
were studied in growing rats.
METHODS:
Nutrition assessment was based on chemical analysis of lentil protein, energy, total and
available starch, lipid and calcium composition, and the digestive and metabolic use of nitrogen and
calcium by rats. Lentils used for the present study had crude protein and calcium contents of 25.5% and
0.07%, respectively. Heating lentils to 120°C at 1 atm for 30 min decreased trypsin inhibitor activity,
phytate, and tannin content by 76%, 8%, and 12%, respectively, but did not improve dietary intake or
digestive use of protein compared with untreated raw control lentils.
RESULTS:
Mineral, vitamin, and olive oil supplementation of raw or autoclaved lentils signi?cantly
improved daily food intake and nutritive use of nitrogen and calcium. The best results were obtained for
the rats fed with a diet of raw lentils supplemented with a premix of minerals and vitamins.
CONCLUSIONS: There was a direct correlation between calcium balance and weight gain in animals (r
0.89) and between the calcium balance and nitrogen balance (r
0.86).
Nutrition 2003;19:451– 456.
©Elsevier Inc. 2003
KEY WORDS: lentils, autoclave, mineral and vitamin supplementation, digestive and metabolic use, protein,
calcium
INTRODUCTION
rected by mineral and vitamin forti?cation. Supplementation of
minerals and vitamins is a common practice in commercial
The nutritional importance of legumes as human or animal food
vegetable-based diets for animal production to compensate for
resources that provide signi?cant amounts of dietary protein, ?ber,
their naturally low mineral availability and to enhance the nutritive
complex carbohydrates, and minerals has been studied extensive-
use of these feeds.8 Mineral and vitamin supplementation is also
ly.1 The lentil is a widely consumed legume in the Mediterranean
necessary for humans in certain physiologic or pathologic condi-
area, and in Spain is surpassed only by the chickpea. Nevertheless,
tions9 and is becoming increasingly popular in many foods for
the nutritional value of lentils can be compromised by a de?cit or
human consumption.10 In previous studies,3,5 we used a commer-
low availability of certain essential nutrients such as sulfur amino
cial variety of lentil purchased in the local market. For this study,
acids, lipids, calcium, or vitamin D and by the presence of anti-
we chose a variety of lentil grown under controlled conditions of
nutritional factors such as trypsin inhibitors, -amylase inhibitors,
soil and humidity. The objectives of the study were to 1) improve
tannins, or phytic acid.
the nutritive use of protein from lentils with the use of a thermal
Technological treatments such as autoclaving, germination,
treatment in an autoclave at 120°C, 1 atm, for 30 min to remove
soaking, and cooking2–5 have been applied to reduce the level of
heat-sensitive antinutritional factors present in this legume and 2)
antinutritional factors present in legumes and to improve their
test the effect of mineral, vitamin, and olive oil supplementation on
nutritional value. Autoclaving has been used to destroy the heat-
the nutritive use of protein and calcium from lentils in growing
labile antinutrients present in legumes and to increase the digestive
rats.
use of protein from this foodstuff.6 However, extreme heating
conditions may cause irreversible damage to protein and decrease
the nutritive value of heat-treated foods.7
Low levels of calcium in lentils can be aggravated further by its
MATERIALS AND METHODS
reduced availability.5 De?ciencies and low availability of calcium
and other essential minerals and vitamins in lentils can be cor-
Diets
The raw lentil ?our (RL) diet consisted of Lens culinaris M., var
vulgaris, cultivar. magda-20 grown at the Instituto Agronomico
This research was supported by project ALI 96-0480.
Provincial (Albacete, Spain) under the following conditions: soil
Correspondence to: Gloria Urbano, PhD, Departamento de Fisiolog?´a,
texture consisted of sand, clay, and loam, with an alkaline pH and
Facultad de Farmacia, Campus Universitario de Cartuja s/n, Granada
a high lime content. Average soil depth of the plot was 40 cm and
18071, Spain. E-mail: paranda@platon.ugr.es
the irrigation water supply was 1000 m3/ha.
Nutrition 19:451– 456, 2003
0899-9007/03/$30.00
©Elsevier Inc., 2003. Printed in the United States. All rights reserved.
PII S0899-9008(02)01011-0

---

452
Porres et al.
Nutrition Volume 19, Number 5, 2003
The autoclaved lentil (AL) diet consisted of lentil ?our made
the diet was consumed ad libitum. The rats were handled at all
from whole raw lentil seeds autoclaved at 120°C, 1 atm, for 30
times in accordance with current European regulations with regard
min.
to laboratory animals.
The RM diet consisted of raw lentil ?our supplemented with a
mineral and vitamin premix (3.5% mineral and 1% vitamin) ac-
Biological Indices
cording to the recommended dietary allowances for growing rats.11
The AM diet consisted of the AL diet supplemented with the
The following indices and parameters were determined for each
same mineral–vitamin premix used for the RM diet.
group according to the formulas given below: growth ef?ciency
The AMF diet consisted of the AM diet supplemented with 4%
coef?cient (weight gain in grams per day/protein intake in grams
olive oil and vitamin D (1000 IU/kg).
per day); food transformation index (total intake in grams of dry
The vitamin premix contained the following ingredients (g/kg
matter per day/increase in body weight in grams per rat per day);
of premix): thiamin, 0.6; ribo?avin, 0.6; pyridoxine, 0.7; nicotin-
index of available starch (weight gain in grams per day/available
amide, 3.0; calcium pantothenate, 1.6; folic acid, 0.2; biotin, 0.02;
starch intake in grams per day); apparent digestibility coef?cient
cyanocobalamin, 2.5; and sucrose to make 1 kg of mix. The
(ADC) for nitrogen and calcium; nitrogen and calcium retention
mineral premix contained the following ingredients (g/kg of pre-
(balance); and percentage of nitrogen or calcium retention/nitrogen
mix): calcium carbonate, 357; potassium phosphate, 196, sodium
or calcium absorption (%R/A):
chloride, 74; potassium citrate, monohydrate, 71; potassium sul-
fate, 46; magnesium oxide, 24; manganous carbonate (43% to 48%
ADC
[(I
F)/I]
100
manganese), 0.63; ferric citrate (16% to 17% iron), 6.00; zinc
carbonate (56% zinc), 1.65; cupric carbonate (53% to 55% cop-
balance
I
(F
U)
per), 0.30; potassium iodate, 0.01; sodium selenate, 0.01025; chro-
mium potassium sulfate, dodecahydrate, 0.275; and sucrose to
%R/A
{[I
(F
U)]/(I
F)}
100
make 1 kg of mix.
where I
intake, F
fecal excretion, and U
urinary excretion.
Analysis
Statistical Analysis
The moisture content of the different lentil diets was determined
One-way analysis of variance was applied to the data with the use
by drying to constant weight in an oven at 105
1°C. Total
of Statgraphic Statistical Graphics 2.1 System Software (Statistical
nitrogen was determined according to Kjeldahl’s method. Crude
Graphics Corporation, Rockville, MD, USA). Differences between
protein was calculated as N
6.25. Energy was measured with an
means were compared with Duncan’s test. The level of signi?-
adiabatic bomb calorimeter (Gallenkamp, UK). Total fat was de-
cance was set at P
0.05.
termined by gravimetry of the ethyl ether extract after acid hydro-
lysis of the sample. Total starch was determined by using the
technique of Carpita and Kabanus12 as modi?ed by Bakhsh et al.13
RESULTS
Available starch was determined after sample hydrolysis with
amyloglucosidase for 30 min. Ash was measured by calcination at
Chemical Composition
500°C to a constant weight. Calcium was determined with a
Perkin-Elmer 1100B atomic absorption spectrophotometer (Oak
The nutrient composition of the different lentil diets tested is
Brook, IL, USA). Lanthanum chloride was added to the samples to
summarized in Table I. The raw lentils used for the present study
prevent interference with calcium determination caused by phos-
(RL) had an energy content of 18.7 kJ/g DM and crude protein,
phate ions. Phytic acid was determined by the colorimetric method
total starch, available starch, lipid, ash, and calcium contents of
of Latta and Eskin.14 Condensed tannins were determined accord-
25.6%, 48.0%, 43.8%, 2.1%, 3.4%, and 0.07%, respectively. Heat-
ing to the method of Reed et al.,15 and catechins were determined
ing to 120°C at 1 atm for 30 min (AL) decreased total starch
according to the method Swain and Hillis.16 Trypsin inhibitor
content by 11.5% and available starch by 4.8%, without affecting
activity (TIA) was measured by using the method of Kakade et
crude protein, lipid, ash, or calcium content. Supplementation of a
al.,17 with extraction performed as described by Valdebouze et
mineral–vitamin premix to the diet of raw and autoclaved lentils
al.18
-Amylase inhibitor activity was determined with the tech-
(RM, AM, and AMF) resulted in a 1.7-fold increase in ash con-
nique described by Piergiovanni.19
centration and an eight-fold increase in calcium concentration.
Adding 4% olive oil to the mineral–vitamin premix increased the
total fat content of the AMF diet to 6.6 g/100 g DM. Mineral and
Biological Methods
vitamin supplementation caused a foreseeable decrease in crude
We used a biological balance technique that records changes in
protein, total starch, and available starch due to the dilution effect.
body weight and food intake and then calculates nitrogen and
The antinutrient composition of lentils is shown in Table II.
calcium intake and fecal and urinary nitrogen and calcium excre-
Autoclave processing decreased the contents of trypsin inhibitor
tion. Five 10-d experiments in which lentils were the only food
activity, phytate, tannin, and catechin by 76%, 8%, 12%, and 33%,
source were carried out. During the ?rst 3 d of experiments, the
respectively. No
-amylase inhibitor activity was detected in any
rats were allowed to adapt to the diet and experimental conditions,
of the diets studied.
and the main experimental period comprised the next 7 d, during
which body weight and food intake were recorded and feces and
Biological Analysis
urine were collected for analysis.
In each experiment we used 10 young albino Wistar rats (?ve
DIETARY INTAKE AND WEIGHT GAIN.
Daily food intake
male and ?ve female). The growing animals (recently weaned)
(g/d or g/100 g of body weight) was greater in diet RM (P
0.05)
with an initial body weight of 57.3
0.6 g were housed from day
than in the other lentil diets studied (Table III). Similar results
0 of the experiment in individual stainless steel metabolic cages
were observed for energy, protein, and available starch intake.
designed for the separate collection of feces and urine; the cages
Food intake expressed as g/100 g of body weight was the lowest
were in a well-ventilated, thermostatically controlled room (21
for the AMF diet. Fat intake was signi?cantly higher with the RM
2°C) with a 12-h light/12-h dark cycle. Throughout the experi-
than with the RL, AL, or AM diet and highest for the AMF diet.
mental period all rats had free access to doubly distilled water, and
Weight gain among rats fed the RM, AM, and AMF diets was

---

Nutrition Volume 19, Number 5, 2003
Mineral Supplementation Improves Nutritive Use of Lentils
453
TABLE I.
NUTRIENT COMPOSITION OF THE DIFFERENT LENTIL DIETS
Energy
Protein
Total starch
Available starch
Total fat
Ash
Calcium
Diets
(kJ/g DM)
(g/100g DM)
(g/100g DM)
(g/100g DM)
(g/100g DM)
(g/100g DM)
(mg/100g DM)
RL
18.7
25.6
48.0
43.8
2.1
3.42
69.1
AL
18.8
25.3
42.5
41.7
2.2
3.53
73.6
RM
17.9
23.3
45.7
41.8
2.0
5.74
580.1
AM
18.1
24.3
39.5
38.8
2.1
5.87
598.4
AMF
19.1
23.5
37.8
37.1
6.6
5.57
588.8
AL, autoclaved lentils; AM, autoclaved lentils supplemented with a mineral–vitamin premix (3.5% mineral premix and 1% vitamin premix); AMF, au-
toclaved lentils supplemented with a mineral–vitamin premix (3.5% mineral premix and 1% vitamin premix), 4% olive oil, and vitamins A and D: DM,
dry matter: RL, raw lentils; RM, raw lentils supplemented with a mineral–vitamin premix (3.5% mineral premix and 1% vitamin premix)
signi?cantly higher than that of those fed the RL and AL diets. The
signi?cantly as a consequence of mineral–vitamin supplementa-
greatest weight gain was found for the RM diet. Rats fed the RM,
tion and the highest metabolic use of calcium assessed as balance
AM, and AMF diets had a signi?cantly larger growth ef?ciency
or %R/A corresponded to the RM diet.
coef?cient, food transformation index, and index of available
No differences related to sex were observed for any of the
starch than did the animals fed the RL and AL diets (P
0.05).
parameters or nutritional indices calculated. Therefore, the results
Similar values were obtained for these nutritional indices from the
expressed are the means of ?ve female and ?ve male rats.
three diets supplemented with minerals and vitamins.
DISCUSSION
DIGESTIVE AND METABOLIC USE OF NITROGEN.
Nitro-
gen absorption (Table IV) in absolute values was signi?cantly
Chemical Analysis of Diets
higher in animals fed the RM diet than in those fed the other lentil
diets studied. No differences were found in the RL, AL, AM, and
Crude protein, total starch, lipid, ash, and calcium contents of the
AMF diets. Digestive use of nitrogen, calculated as the ADC, was
lentil variety used for the present study fell within the range of
not affected by autoclave treatment or supplementation with min-
values found in the literature.3,20 Thermal treatment of whole lentil
erals, vitamins, and olive oil.
seeds at 120°C, 1 atm, for 30 min caused a 12% reduction in total
Nitrogen balance and %R/A was signi?cantly improved by the
starch content, similar to that observed by Urbano et al.3 after dry
mineral–vitamin supplementation of lentils. The highest increase
heating ?our of a different lentil variety at 120°C, 1 atm, for 15
was obtained for the RM diet compared with the AM and AMF
min. Nevertheless, the heat treatment applied in our experimental
diets (P
0.05).
conditions has been bene?cial for the potential digestibility of
Digestive and metabolic uses of calcium from the different
starch by reducing resistant starch content from 9% in raw lentils
lentil-based diets are summarized in Table V. Calcium intake is a
to 2% in autoclaved lentils.
re?ection of food intake and the amount of calcium present in the
The conditions used for the thermal treatment employed in the
diet. The highest calcium intake was found in animals fed the RM
present study were more ef?cient at reducing the levels of TIA and
diet. Calcium ADC of the RL, AL, RM, and AM diets did not
tannins than was a previously used treatment of dry heat at 120°C,
differ signi?cantly, whereas supplementation of 4% olive oil and
1 atm, for 15 min,3 but decreased TIA to a lesser extent than did
vitamin D to the AMF diet slightly increased calcium ADC.
the different cooking processes assayed in lentils by Vidal-
Heat treatment of lentils (AL) slightly decreased the %R/A of
Valverde et al.2
calcium compared with the RL diet, reaching values similar to
The mineral–vitamin premix added to the diets of raw and
those of the AM and AMF diets. Calcium retention improved
autoclaved lentils ensured the intake of a suf?cient amount of
TABLE II.
ANTINUTRIENT COMPOSITION OF THE DIFFERENT LENTIL DIETS*
Trypsin inhibitor activity
Tannins
Catechins
Tannin/
Phytate
Diets
(TIU/mg DM)
(mg/g DM)
(mg/g DM)
catechin
(mg/g DM)
RL
4.79
0.16a
1.80
0.12a
0.52
0.03a
3.46
6.23
0.30a
AL
1.15
0.11b
1.58
0.13b
0.35
0.02b
4.51
5.76
0.25a
RM
4.56
0.15a
1.72
0.13a
0.50
0.04a
3.44
5.96
0.32a
AM
1.05
0.10b
1.44
0.12b
0.32
0.02b
4.50
5.24
0.21b
AMF
1.01
0.10b
1.40
0.12b
0.31
0.02b
4.52
5.10
0.22b
* The same superscript letter in the same column indicates no signi?cant differences (P
0.05). Values are means
standard deviation.
AL, autoclaved lentils; AM, autoclaved lentils supplemented with a mineral–vitamin premix (3.5% mineral premix and 1% vitamin premix); AMF, au-
toclaved lentils supplemented with a mineral–vitamin premix (3.5% mineral premix and 1% vitamin premix), 4% olive oil, and vitamins A and D; DM,
dry matter; RL, raw lentils; RM, raw lentils supplemented with a mineral–vitamin premix (3.5% mineral premix and 1% vitamin premix): TIU, trypsin
inhibitor units

---

454
Porres et al.
Nutrition Volume 19, Number 5, 2003
TABLE III.
FOOD INTAKE AND WEIGHT GAIN OF RATS FED THE DIFFERENT LENTIL DIETS*
Intake
Protein
Total fat
Available
Intake
(g/100
Energy
intake
intake
starch
Weight
Diets
(g/d)
g weight)
intake
(g/d)
(g/d)
intake (g/d)
(g/d)
GEC
TI
IAS
RL
8.8
0.25a 15.70
0.39a 165.03
4.71a
2.26
0.06a
0.18
0.005a
3.87
0.11ab 1.44
0.08a 0.64
0.003a 6.27
0.28a 0.37
0.02a
AL
9.5
0.36a 14.92
0.24a 177.87
6.12ab 2.39
0.08ab 0.21
0.007ab 3.95
0.14b
1.37
0.09a 0.58
0.03a
7.13
0.46b 0.35
0.02a
RM
14.9
0.56b 18.13
0.51b 266.71
9.98c
3.47
0.13c
0.30
0.011c
6.23
0.23c
4.60
0.22b 1.33
0.06b
3.27
0.17c 0.74
0.03b
AM
10.6
0.50c 14.74
0.84a 192.15
9.05b
2.57
0.12b
0.23
0.011b
4.12
0.19b
2.82
0.22c 1.10
0.08c
3.91
0.27c 0.69
0.05b
AMF
9.3
0.24a 12.96
0.23c 177.36
4.56ab 2.18
0.06a
0.61
016d
3.45
0.09a
2.70
0.13c 1.24
0.05bc 3.50
0.14c 0.78
0.03b
* The same superscript letter in the same column indicates no signi?cant differences (P
0.05). Values are means
standard error of the mean of 10
Wistar rats.
AL, autoclaved lentils; AM, autoclaved lentils supplemented with a mineral–vitamin premix (3.5% mineral premix and 1% vitamin premix); AMF, au-
toclaved lentils supplemented with a mineral–vitamin premix (3.5% mineral premix and 1% vitamin premix), 4% olive oil, and vitamins A and D;
GEC, growth ef?ciency coef?cient; IAS, index of available starch; RL, raw lentils; RM, raw lentils supplemented with a mineral–vitamin premix (3.5%
mineral premix and 1% vitamin premix): TI, food transformation index
essential minerals and vitamins to meet the nutrient requirements
Overcoming the mineral and vitamin de?cits in the diets of raw
of the growing rat11 with the exception of vitamin D, which was
and autoclaved lentils by means of supplementation with a
supplemented speci?cally in the AMF diet in addition to 4% olive
mineral–vitamin premix signi?cantly improved daily food intake.
oil.
Nevertheless, the improvement was signi?cantly higher with the
raw than with the autoclaved lentil diet. The signi?cantly lower
Biological Analysis
dietary intake of animals fed the AMF versus the AM diet could be
related to the higher energy content of the diet supplemented with
Food intake with the diets of raw or autoclaved lentils was low
4% olive oil.
compared with a standard diet of casein and methionine with a
similar protein concentration.4 Lower dietary intakes for legume-
Digestive and Metabolic Uses of Nitrogen
based diets have been related to the presence of unpalatable
components ( -galactosides or tannins) and de?ciencies in certain
Digestive use of nitrogen from the raw lentils used in the present
essential amino acids, minerals, and vitamins, which may lead to
study (ADC) was in agreement with the values reported by Car-
nutrient imbalance. Despite the reduction of
-galactoside,3,4 tan-
bonaro et al.23 and similar to those described by Nestares et al. for
nin, and phytate content produced by thermal treatment, dietary
the chickpea,21 but lower than the digestive use of nitrogen re-
intake was not signi?cantly affected in the animals fed the auto-
ported for the faba bean4 or the pea.24 The reduction in TIA found
claved lentil diet compared with the raw lentil diet. The content of
after autoclave treatment (from 4.79 to 1.15 TIU/mg DM) did not
antinutritional factors may not be high enough in lentils to play a
improve the digestive use of nitrogen when compared with the RL
major role in daily food intake, as observed for the faba bean,4 but
diet. Similar results have been observed for faba beans, in which a
in contrast to the chickpea.21 Moreover, Maillard products formed
reduction of TIA from 2.62 to 0.81 TIU/mg DM after thermal
during thermal treatment can negatively affect the palatability of
treatment did not result in a signi?cant effect on nitrogen ADC.4
heat-treated foods22 and might have affected the palatability of
These results suggested that the improvement of nitrogen digest-
lentils, thus hindering the bene?cial effects of removing antinutri-
ibility resulting from the removal of TIA is counteracted by an
tional factors.
increase in tannin polymerization as re?ected in the higher tannin:
TABLE IV.
DIGESTIVE AND METABOLIC USES OF NITROGEN*
Nitrogen intake
Nitrogen absorbed
Balance
Diets
(mg/d)
(mg/d)
ADC (%)
(mg/d)
% R/A
RL
360.5
10.2ab
285.0
9.1ab
79.0
0.48a
74.9
3.9a
26.4
1.52a
AL
380.0
12.9abd
300.3
10.9ab
79.0
0.94a
85.2
7.4ab
25.8
2.83a
RM
554.9
20.5c
436.1
19.8c
78.4
1.01ab
209.7
11.3c
48.0
1.20b
AM
410.3
19.4d
310.6
15.0b
75.7
0.99b
107.6
6.6d
34.9
2.02c
AMF
348.0
8.9a
270.4
6.8a
77.8
0.89ab
99.9
4.4bd
37.0
1.53c
* The same superscript letter in the same column indicates no signi?cant differences (P
0.05). Values are means
standard error of the mean of 10
Wistar rats.
ADC, apparent digestibility coef?cient; AL, autoclaved lentils; AM, autoclaved lentils supplemented with a mineral–vitamin premix (3.5% mineral pre-
mix and 1% vitamin premix); AMF, autoclaved lentils supplemented with a mineral–vitamin premix (3.5% mineral premix and 1% vitamin premix),
4% olive oil, and vitamins A and D; %R/A, percentage of nitrogen or calcium retention/nitrogen or calcium absorption: RL, raw lentils; RM, raw len-
tils supplemented with a mineral–vitamin premix (3.5% mineral premix and 1% vitamin premix)

---

Nutrition Volume 19, Number 5, 2003
Mineral Supplementation Improves Nutritive Use of Lentils
455
TABLE V.
DIGESTIVE AND METABOLIC USES OF CALCIUM*
Ca intake
Ca absorbed
Balance
Diets
(mg/d)
(mg/d)
ADC (%)
(mg/d)
% R/A
RL
6.1
0.17a
3.3
0.11a
54.3
0.93a
2.53
0.10a
76.3
1.10a
AL
6.7
0.32a
4.0
0.21a
59.8
2.24ab
2.82
0.18a
70.5
1.89ab
RM
86.3
3.18b
49.5
2.45b
57.3
1.83ab
42.8
2.63b
82.8
3.7c
AM
63.6
3.31c
35.9
1.90c
56.8
2.34ab
24.7
1.70c
68.7
2.7b
AMF
54.7
1.41d
33.4
1.33c
61.2
1.98b
22.7
0.80c
68.1
1.28b
* The same superscript letter in the same column indicates no signi?cant differences (P
0.05). Values are means
standard error of the mean of 10
Wistar rats.
ADC, apparent digestibility coef?cient; AL, autoclaved lentils; AM, autoclaved lentils supplemented with a mineral–vitamin premix (3.5% mineral pre-
mix and 1% vitamin premix); AMF, autoclaved lentils supplemented with a mineral–vitamin premix (3.5% mineral premix and 1% vitamin premix),
4% olive oil. and vitamins A and D; CA, calcium: %R/A, percentage of nitrogen or calcium retention/nitrogen or calcium absorption; RL, raw lentils;
RM, raw lentils supplemented with a mineral–vitamin premix (3.5% mineral premix and 1% vitamin premix)
catechin ratio (3.46 versus 4.51 for RL and AL, respectively) and
tannin (15%) or phytate (8%) contents of lentils caused by the
by protein denaturation caused by the thermal treatment.25 Further,
autoclave treatment was not as ef?cient at improving calcium
the low levels of TIA in lentils compared with other legumes such
ADC as the thermal treatment used in previous experiments,5 in
as chickpeas21 or soybeans26 may be partly responsible for the lack
which a 13% reduction of phytate signi?cantly improved the
of effect of autoclave treatment on protein digestibility. Mineral–
digestive use of calcium. The enhancing effect of vitamin D on
vitamin supplementation did not affect the digestive use of nitro-
calcium digestibility has been widely described.31 However, di-
gen. Therefore, the differences in net absorption observed between
gestive use of calcium from diet AMF increased only slightly after
the RM and RL diets or between the AM and AL diets resulted
fat and vitamin D supplementation compared with the AM diet.
from the higher nitrogen intake with the diets supplemented with
The limited effect of vitamin D on the digestive use of calcium
minerals and vitamins.
under our experimental conditions may have been caused by the
The nitrogen balance and the nutritional indices obtained for
short experimental period and/or good storage of vitamin D in the
the RL diet denoted a protein of low quality. The nutritional value
experimental animals.
of lentil protein can be compromised by its de?cit of sulfur amino
acids, as demonstrated by Urbano et al.3 who obtained a signi?cant
Thermal treatment of foods has been related to an impaired
improvement in the metabolic use of nitrogen and the protein
metabolic use of protein and calcium.7,22,32 This effect was ob-
ef?ciency ratio after supplementing a diet of raw lentils with 0.5%
served in our experiments, in which a slight decrease of calcium
methionine. The protein quality of raw lentils used in the present
%R/A was obtained for the diet of autoclaved lentils compared
study was poorer than that of other legumes such as faba beans or
with the diet of raw lentils. The effect of thermal treatment on the
lupins,4,27 but higher than that of chickpeas.21 Excessive thermal
metabolic use of calcium was intensi?ed in the diets of autoclaved
treatment of foods can affect the metabolic use of protein.28
lentils supplemented with a mineral–vitamin premix (AM and
However, no signi?cant differences in nitrogen balance, %R/A
AMF).
nitrogen, or growth ef?ciency coef?cient were observed between
Because there was no signi?cant difference in the calcium
the RL and AL diets in the present study.
ADC between the different lentil diets tested, the higher net
The higher nitrogen balance obtained for the rats fed the raw
absorption of calcium by rats fed the diet of raw lentils supple-
lentil diet supplemented with a mineral–vitamin premix was due to
mented with a mineral–vitamin premix was a consequence of their
a greater food intake and metabolic use of nitrogen observed in this
higher intake of this mineral. The higher net absorption of calcium
group. The greater food intake led to a signi?cantly higher net
led to a greater retention and metabolic use. This was re?ected in
absorption of nitrogen and intake of available starch. As a result of
the %R/A value (82.8
3.7%) that was signi?cantly higher than
the higher intake of dietary carbohydrates, protein can be directed
those in the other experimental diets studied, approaching the
to growth promotion rather than to the metabolism of the produc-
%R/A reported for a control diet of casein methionine (91.2
tion of energy and subsequently excreted in the urine. This was
1.81%).5 Under our experimental conditions, the metabolic use of
con?rmed by the higher %R/A of nitrogen, growth ef?ciency
calcium strongly correlated with the nutritive use of protein and,
coef?cient, and index of available starch results obtained for the
hence, the growth of the animals. This ?nding was con?rmed by
RM diet as opposed to the RL and AL diets. The metabolic use of
nitrogen in the groups fed with the diets of autoclaved lentil
the strong correlation coef?cients between calcium retention and
supplemented with a mineral–vitamin premix followed the same
nitrogen retention (r
0.86) and between calcium retention and
trend as in the RM diet. However, the lower dietary intake of
weight gain (r
0.89). This is not surprising in view of the plastic
nitrogen and available starch observed in these two diets signi?-
function of calcium and nitrogen in the organism and their impor-
cantly decreased the metabolic use of protein (nitrogen balance
tance for the tissue and structural development of young animals.
and %R/A) when compared with the diet of raw lentil supple-
In conclusion, the content of TIA, tannins, and phytate of Lens
mented with a mineral–vitamin premix.
culinaris M., var vulgaris, cultivar. magda-20 did not seem to
have a signi?cant effect on the digestive use of protein and
Digestive and Metabolic Uses of Calcium
calcium. Supplementation of raw lentil ?our with a mineral–
vitamin premix formulated to meet the nutrient requirements of the
The intake and digestive use of calcium with the raw lentil diet was
growing rat led to a signi?cant increase in food intake and a
lower than that found in a different variety of lentil5 and in other
considerable improvement in the nutritive use of carbohydrates,
legumes such as chickpeas29 or faba beans.30 The reduction in the
protein, and calcium.

---

456
Porres et al.
Nutrition Volume 19, Number 5, 2003
ACKNOWLEDGMENTS
17. Kakade ML, Rackis JJ, McGhee JE, Puski G. Determination of trypsin inhibitor
activity of soy bean products: a collaborative analysis of an improved procedure.
The authors thank Encarnacio´n Colmenero, Rosa Jime´nez, Isabel
Cereal Chem 1974;51:376
Estrella, and Cristina Sotomayor for their skillful technical
18. Valdebouze P, Bergeron E, Gaborit T, Delort-Laval J. Content and distribution of
assistance.
trypsin inhibitor and haemaglutinins in some legume seeds. Can J Plant Sci
1980;60:695
19. Piergiovanni AR. Effects of some experimental parameters on the activity of
cowpea
-amylase inhibitors. Lebens Wiss Unters Technol 1992;25:321
REFERENCES
20. Candela M, Astiasaran I, Bello J. Cooking and warm-holding: effect on general
composition and amino acids of kidney beans (Phaseolus vulgaris), chickpeas
1. Nwokolo E. The need to increase consumption of pulses in the developing world.
(Cicer arietinum), and lentils (Lens culinaris). J Agric Food Chem 1997;45:4763
In: Nwokolo E, Smartt J, eds. Food and feed from legumes and oilseeds. London:
21. Nestares T, Lo´pez-Fr?´as M, Barrionuevo M, Urbano G. Nutritional assessment of
Chapman & Hall, 1996:3
raw and processed chickpea (Cicer arietinum L) protein in growing rats. J Agric
2. Vidal-Valverde C, Fr?´as J, Estrella I, et al. Effect of processing on some
Food Chem 1996;44:2760
antinutritional factors of lentils. J Agric Food Chem 1994;42:2291
22. Sarria´ B, Lo´pez-Fandin˜o R, Vaquero P. Does processing of a powder or in-bottle-
3. Urbano G, Lo´pez-Jurado M, Herna´ndez J, et al. Nutritional assessment of raw,
sterilized liquid infant formula affect calcium bioavailability? Nutrition 2001;17:
heated, and germinated lentils. J Agric Food Chem 1995;43:1871
326
4. Fernandez M, Lopez-Jurado M, Aranda P, Urbano G. Nutritional assessment of
23. Carbonaro M, Cappelloni M, Nicoli S, Lucarini M, Carnovale E. Solubility-
raw and processed faba bean (Vicia faba L) cultivar major in growing rats. J
digestibility relationship of legume proteins. J Agric Food Chem 1997;45:3387
Agric Food Chem 1996;44:2766
24. Oru´e E, Butro´n J, Iba´n˜ez F, Alonso R, Marzo F. The effect of germination and
5. Urbano G, Lo´pez-Jurado M, Ferna´ndez M, et al. Ca and P bioavailability of
extrusion on the nutritional quality of peas (Pisum sativum L. cv. Ballet). In:
processed lentils as affected by dietary ?ber and phytic acid content. Nutr Res
Jansman AJM, Hill GD, van der Poel AFB, eds. Recent advances of research in
1999;19:49
antinutritional factors in legume seeds and rapeseed. Proceedings of the Third
6. Siddhuraju P, Becker K. Effect of various domestic processing methods on
International Workshop on Antinutritional Factors in Legume Seeds and Rape-
antinutrients and in vitro protein and starch digestibility of two indigenous
seed. Wageningen Press, 1998:417
varieties of indian tribal pulse, Mucuna pruriens var. utilis. J Agric Food Chem
25. Carbonaro M, Cappelloni M, Sabbadini S, Carnovale E. Disul?de reactivity and
2001;49:3058
in vitro protein digestibility of different thermal-treated milk samples and whey
7. O’Brien J, Morrissey PA. Nutritional and toxicological aspects of the Maillard
proteins. J Agric Food Chem 1997;45:95
browning reactions in foods. Crit Rev Food Sci Nutr 1989;28:211
26. Gaborit T, Quillien L, Guegen J. Determination of trypsin inhibitor activity in
8. Deyhim F, Stoecker BS, Adeleye BG, Teeter RG. The effects of heat distress,
seeds by a microtitre plate method. In: van der Poel AFB, Huisman J, Saini HS,
environment, vitamin, and trace mineral supplementation on performance, blood
eds. Recent advances of research in antinutritional factors in legume seeds.
constituents, and tissue mineral concentrations in broiler chickens. Nutr Res
Proceedings of the Second International Workshop on Antinutritional Factors
1995;15:521
(ANFs) in Legume Seeds. Wageningen Press, 1993:37
9. Weaver CM. Calcium in food forti?cation strategies. Int Dairy J 1998;8:443
27. Hill GD. The composition and nutritive value of lupin seed. Nutr Abstr Rev B
10. Krishnakumar V. Mineral forti?cation in food and supplements. Int Food Ingred
1977;47:511
1999;6:11
28. Friedman M. Food browning and its prevention: an overview. J Agric Food Chem
11. National Research Council. Nutrient requirements of laboratory animals, 4th rev
1996;44:631
ed. Washington, DC: National Academy Press, 1995
29. Nestares T, Barrionuevo M, Urbano G, Lo´pez-Fr?´as M. Effect of processing
12. Carpita CN, Kabanus J. Extraction of starch by dimethylsulfoxide and quanti?-
methods on the calcium, phosphorus, and phytic acid content and nutritive
cation by enzymatic assay. Anal Biochem 1987;161:132
utilization of chickpeas (Cicer arietinum L). J Agric Food Chem 1999;47:2807
13. Bakhsh A, Jones AD, Hedley CL, Lambert N. Genetic variation for seed storage
30. Lo´pez-Jurado M, Urbano G, Ferna´ndez M Bioavailability of calcium in raw and
product composition in lentils (Lens culinaris). Aspects Appl Biol 1991;27:279
processed faba beans. In: Schlemmer U, ed. Bioavailability ’93. Nutritional,
14. Latta M, Eskin M. A simple and rapid colorimetric method for phytate determi-
chemical and food processing implications of nutrient availability, Vol 2. Ettlin-
nation. J Agric Food Chem 1980;28:1313
gen, Germany, 1993:155
15. Reed JD, McDowell RE, Van Soest PJ, Horvart PJ. Condensed tannins: a factor
31. Schaafsma G. Bioavailability of calcium and magnesium. Eur J Clin Nutr
limiting the use of cassava forage. J Sci Food Agric 1982;33:213
1997;51:S13
16. Swain T, Hillis WE. The phenolic constituents of Prunus domestica I The
32. O’Brien J, Morrissey PA. Metal ion complexation by products of the Maillard
quantitative analysis of phenolic constituents. J Sci Food Agric 1959;10:63
reaction. Food Chem 1997;58:17

---

Document Outline

• Effect of Heat Treatment and Mineral and Vitamin Supplementation on the Nutritive Use of Protein and Calcium From Lentils (Lens culinaris M.) in Growing Rats
  • INTRODUCTION
  • MATERIALS AND METHODS
    • Diets
    • Analysis
    • Biological Methods
    • Biological Indices
    • Statistical Analysis
  • RESULTS
    • Chemical Composition
    • Biological Analysis
      • DIETARY INTAKE AND WEIGHT GAIN.
      • DIGESTIVE AND METABOLIC USE OF NITROGEN.
  • DISCUSSION
    • Chemical Analysis of Diets
    • Biological Analysis
    • Digestive and Metabolic Uses of Nitrogen
    • Digestive and Metabolic Uses of Calcium
  • REFERENCES

---