Journal of Agricultural Chemistry and Environment, 2014, 3, 53-56
Published Online April 2014 in SciRes. http://www.scirp.org/journal/jacen
How to cite this paper: Pardo, M.E.S., et al. (2014) Chemical Characterisation of the Industrial Residues of the Pineapple
(Ananas comosus). Journal of Agricultural Chemistry and Environment, 3, 53-56.
Chemical Characterisation of the Industrial
Residues of the Pineapple (Ananas comosus)
María Elena Sánchez Pardo1*, María Elena Ramos Cassellis2, Rosalva Mora Escobedo1,
Epifanio Jiménez García1
1Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Prolongación de Carpio y Plan de Ayala
S/N, Col. Sto. Tomás. C.P. 11340, México D.F., México
2Benemérita Universidad Autónoma de Puebla, Av.San Claudio y 18 sur Edif.106, Ciudad Universitaria, Puebla,
Pue.3ExHacienda san Juan Molino, km 1.5 carretera Estatal Tecuexcomac-Tepetitla, México
Email: *alimentoselena@h otmail.com
Received January 2014
In Mexico pineapple processing produces industrial residues with a high concentration of dietary
fibre. The aim of this study was to quantify the constituents of the fibrous residues from the in-
dustrial processing of pineapples which exhibited low concentrations of lignin.
Pineapple; Total Dietary Fibre; Hemicelluloses; Cellulose; Lignin; Pectin
Pineapple (Ananas comosus) is native to the South American continent and is considered an exotic fruit due to
its taste and flavour. In Mexico, pineapple cultivation has a long tradition and is of vital economic and cultural
importance . Mexico is the seventh largest producer of pineapples worldwide. Pineapple residues can account
for 50% of waste weight and generate approximately 10 tons/year of fresh fibre. Larrauri et al. reported that the
external part of the pineapple has a significant content of soluble carbohydrates (as the product of the pulp re-
maining after removal of the edible part) including more than 20% total dietary fibre (TDF), composed mainly
The residual lignocellulosic fibres are polymeric materials of great industrial interest, because they are re-
newable and biodegradable products. Their chemical composition depends on the type and origin of the fibres
which contain different amounts of cellulose, hemicellulose and lignin (dietary fibre). In addition to the amounts
of dietary fibre present in the plant tissues other important aspects but also their chemical (d eg ree of lignification,
type and crystallinity of cellulose) and physical (particle size and shape) properties, because these affect fer-
mentation in the colon as well as the speed of trans it in the gas tro intestinal tract.
Toward this objective, these residues were grouped as the leaf bracts, shell and core for a study of relationship
between the native cellulose phases.
M. E. S. Pardo et al.
2. Materials and Methods
2.1. Raw Materials: Treatment and Classification
The residues were dehydrated in a horizontal drying chamber (Lumisell, Mexico, Mexico) at 60˚C moisture
content was less than 10%.
2.2. Proximate Chemical Analysis of Raw Materials
Proximate chemical analysis for pulp and residues (leaf bracts, shell and core), was performed using the Associ-
ation of Official Analytical Chemists (AOAC) . The total protein was determined [% N × 6.25] using method
993.19; total ash using method 955.04; crude fat using (method 920.39), moisture content using method 934.01,
crude fibre using the acid-alkaline hydrolysis method 991.42, carbohydrates were determined (by subtration as
the nitrogen-free extract, NFE).
The Insoluble (IDF) and soluble (SDF) dietary fibre contents were determined according to the AOAC me-
thod. The samples were dried, defatted and freed from carbohydrate, before the analysis. The (TDF) contents
were corrected for residual protein, and ash. The total dietary fibre content was calculated as the sum of IDF and
Total dietary fibre (method 991.43) was performed according to the technique described in AOAC . The
samples were dried, defatted and free of carbohydrate. It was run blank through entire procedure along with
samples to measure any con tribution reagents to re sidue. In triplicate, 1 ± 0.1 g of sample were suspended en 50
mL of phosphate buffer pH 6.0; submitted to enzymatic hydrolysis by 50 µL of heat stable α-amylase (A-3306,
Sigma Chem. Co. St. Louis MO, USA) in boiling water bath for 30 min. After cooling suspension to room tem-
perature, pH was adjusted to 7.5 ± 0.1 and 100µL of protease (P-3910, Sigma Chem. Co. St. Louis MO, USA)
was added and left to in water bath at 60˚C for 30 min. After cooling pH was adjusted to 4.5 ± 0.1 and 300 µL of
amyloglucosidase (A-9913 Sigma, Chem. Co. St. Louis MO, USA) we re a dde d.
The suspension was left to in water bath at 60˚C for 30 min. After that it was filtered to obtain the supernatant
and the insoluble fr action. The supernatant was precip itated with 95% alcohol to precipitate the SD F and it was
quantified by drying overnight at 105˚C. The insoluble fraction was washed with 78% and 95% alcohol solu-
tions and acetone, respectively, followed by drying overnight at 105˚C to obtain the IDF. The dietary fibre con-
tents were corrected for residual protein, ash and blank. The total dietary fibre was indicated as the sum of IDF +
To quantify the content of hemicellulose, the method for the determination of the neutral detergent fibre (NDF)
content was used as described previously by Van Soest . Consequently, this residue of this analysis was util-
ized to determine the content of cellulose and lignin called the acid detergent fibre (ADF), using method 973.18.
2.3. Statistical Analysis of Data
An analysis of variance was used applying Tukey’s test (α = 0.05) utilizing Statistical Analysis System 8.0 (SAS
Institute Inc., Cary, Nort h California , US A) software .
3. Results and Discussion
In Table 1 the proximate chemical composition of the pineapple pulp and residues (leaf bracts, shell and core) are
shown. Statistical analysis revealed significant differences (p ≤ 0.05) i n the parameters t ota l protein, a s h a nd c rude
fat values. The total protein content ranged from 0.7 g/100g of leaf bracts to 1.58 g/100g of pulp; this total protein
could be mainly attributed to hydroxyproline-rich glycoprotein, Because Bartolome and Ruper ez  an d Smith et
al.  repo rted that the glycop roteins in the sh ells of fruits, are immersed in the primary cell wall forming a net-
work of microfibr ils w ith th e cellulo se . The leaf bracts exhibited th e highest ash content, w hich was twice th at
in the pulp; although the values reported by Chau and Huang  in orange peels (3.3 g/100g) are twice those of
the pineapple’s shell and core. One important consideration is that carbohydrate content was determined by cal-
culation and may include simple sugars such as monosaccharides and disaccharides . The highest content of
crude fat was found in the edible fraction of the pulp, followed by the core (in the case of the residue), whereas
the lowest concentration of crude fat was in the leaf bracts.
M. E. S. Pardo et al.
Table 1. Proximate chemical composition of the residues pineapple (leaf bracts, shell, and core) compared with pulp of
(g/100g) Pulp Leaf bracts Shell Core
Total protein 1.58 ± 0.01d 0.70 ± 0.01a 0.75 ± 0.01b 0.85 ± 0.01c
Ash 3.0 ± 0.01b 7.37 ± 0.0d 1.5 ± 0.00b 1.3 ± 0.00a
Crude fat 3.19 ± 0.00b 3.5 ±.01c 2.0 ± 0.01a 3.17 ± 0.01b
Crude fiber 24.14 ± 0.01a 62.5 ± 0.00c 65 ±0.00c 47.6 ± 0. 00 b
NFE* 68.79 ± 0.00 25.93 ± 0.02 32.1 ± 0.02 47.08 ± 0.01
*NFE = Nitrogen-free extract. Results are given for dry basis and correspond to the average from three independent determinations ± standard
deviation. Different letters in the same row indicate statistically significant difference (p ≤ 0.05) after applying Tukey’s test.
Table 2. Comparison of the chemical composition of the pineapple residues (g/100g Dry weight).
Fibre Leaf bracts Shell Core
IDF 43.53 ± 0.93a 46.20 ± 0.50b 42.92 ± 0.09a
SDF 29.16 ± 0.46b 35.67 ± 0.37c 21.27 ± 0.61a
TDF 74.69 81.8 64.19
Hemicellulose 21.88 ± 0.22a 28.69 ± 0.35b 28.53 ± 1.37b
Cellulose 43.53 ± 1.17c 40.55 ± 1.02b 24.53 ± 1.68a
Lignin 13.88 ± 1.70c 10.01 ± 0.38b 5.78 ± 0.429a
Pectin 2.32 ± 0.37b 2.49 ± 0.20b 1.58 ± 0.17a
3.1. Proximate Chemical Analysis
The raw fibre contents ranged from 24.14%, in the pulp, to 65%, in the leaf bracts. As shown in Table 1, the raw
fibre conten t of the residue fraction is 2.5 times greater than the ed ible fraction (pu lp); these values ar e similar to
those found by Larrauri et al.  and, Bartolome and Ruperez  who al so studied pi ne apple she lls.
3.2. Determination of Soluble (SDF) and Insoluble (IDF) Dietary Fibre
Table 2 shows the results obtained for the different dietary fibre fractions, the statistical analysis showed that
significant differences (p ≤ 0.05) exist among the leaf bracts, shell and core.
The content of dietary fibre (TDF) in the residue depended on the source from which it was extracted, with
the shell having the highest content (81.8 g/100g of dry sample). This value is higher than that reported by Chau
et al.  for orange residues and by Figuerola et al.  for grape peels.
Results are given for dry basis and correspond to the average from three independent determinations ± stan-
dard deviation. Different letters in the same row indicate statistically significant difference (p ≤ 0.05) after ap-
plying Tukey’s test.
Furthermore, the main fibre fraction found in the residues studied fibres was the (IDF fraction) which repre-
sented 56% - 65% of the TDF, similar to the value reported for orange peel , but greater than that reported
for grape peels . These results indicated that the samples tested were composed mainly of cellulose microfi-
brils containing hemicellulos e a nd lignin , as shown in Table 2.
The agroindustrial pineapple residues had a greater fraction of fibre than the edible portion or pulp, and even
more than other agroindustrial residues. The amount of dietary fibre found in the pineapple leaf bracts, shell and
core residues, was relatively high and with the insoluble fraction being the main component.
MESP and RME are members of SNI and recipients of institutional grants (COFAA, EDD and EDI). The doc-
toral studies of MERC have been supported by CONACyT Mexico.
M. E. S. Pardo et al.
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