Effect of Cashew Nut Processing on the Burning - Ceinfo

Proc. Interamer. Soc. Trop. Hort. 47:141-142.
Fruit/Frutales - October 2003
Effect of Cashew Nut Processing on the Burning Sensation Caused by Anacardic Acids
Deborah dos Santos Garruti and Maria Elisabeth Barros de Oliveira, Embrapa Agroindústria Tropical, Fortaleza, CE,
Brazil, 60511-110 [email protected]
Tânia da Silveira Agostini Costa , Embrapa Recursos Genéticos, Brasília-DF, Brazi.l
Katiane Arrais Jales, Laura de Oliveira Andrade and Marcelo Victor Lima, Universidade Federal do Ceará, Fortaleza,
CE, Brazil
Abstract. During the shelling process cashew nuts can be
contaminated by the caustic phenolic lipids from the nut shell,
impairing its appearance and palatability. Samples from either
mechanized and semi-mechanized shelling processes were
evaluated, in both natural and roasted forms, for anacardic acid
content and sensory sensations in the mouth and throat. In
general, cashew nuts from semi-mechanized process showed
higher anacardic acid content and burning sensation intensity.
The roasting procedure (in vegetable oil) resulted in reduction of
anacardic acid level, corresponding to a significant reduction in
the burning sensation intensity. Anacardic acid content highly
correlated with the attribute “burning during chewing”.
Resumo. A contaminação com lipídios fenólicos cáusticos da
casca da castanha para a amêndoa durante o beneficiamento pode
comprometer sua aparência e palatabilidade. Foram avaliadas
amostras de dois tipos de corte, mecanizado e semi-mecanizado,
nas formas natural e frita, quanto ao teor de ácidos anacárdicos e
a intensidade de ardência na boca e garganta. De um modo geral,
amêndoas do processo semi-mecanizado apresentaram maior teor
de ácidos anacárdicos e ardência. A fritura da amêndoa em óleo
vegetal resultou em uma redução significativa do teor de ácidos
anacárdicos e da ardência. Foi verificada uma correlação positiva
altamente significativa entre o teor de ácidos anacárdicos e a
sensação
de
ardência
durante
a
mastigação.
Additional index words. Anacardium occidentale, CNSL, phenolic lipids.
________________________________
The cashew tree (Ancardium occidentale L.), indigenous to Northeast of Brazil, is extensively cultivated in several countries
due to the high value of its edible kernel rich in protein, carbohydrates and unsaturated triglycerides. The kernel, also called
cashew nut, is kidney shaped and light gray in color. This tasty nut is generally consumed after roasting in vegetable oil and
salted. The shell is 2-3 mm thick, with a leathery outer case and a thinner, harder inner case. Between both there is a
honeycomb structure containing the phenolic cashew nut shell liquid (CNSL). The kernel is removed from the shell by roasting
in a hot CNSL bath and mechanically decorticated by impact on a centrifuge (mechanized process) or either by cooking under
high-pressure steam and decorticated by a manual operated blades system (semi-mechanized process). Although the kernels are
protected by a testa skin, during the decorticating process they can get in contact with the caustic CNSL (Strocchi & Lercker,
1979) impairing its sensory properties, mainly appearance (dark spots) and palatability. The objective of this work was to
investigate how cashew nut processing can influence the degree of kernel contamination by phenolic lipids from CNSL and
determine the correlation to sensory sensations caused by their vesicant properties.
Materials and Methods
Material. Cashew nut samples, in both forms, natural and roasted, were collected in four industrial units, two of them using
the mechanized decorticating process and the other two, the semi-mechanized one.
Anacardic acids. Anacardic acid content was measured according to methodology described by Agostini-Costa et al (2003),
consisting on extraction with chloroform, methanol and water, purification in a mini silica column and quantification by
spectrophotometer at 320 nm.
Selection and training of panel members. Ten judges were selected to participate in the experiment based in their acuity. All
the subjects had experience as trained assessors with cashew products and were familiar with the burning sensation and the
descriptive analysis methodology. Training sessions were conducted to explore the terms relevant to the vesicant property and
develop definitions: “burning during mastication” is the stinging sensation in mouth and throat, perceived during sample
mastication; “burning after ingestion” is the stinging sensation in the throat that comes out after the samples’ intake and lasts
for a few minutes. The intensity of the burning sensation was rated on a 9-cm continuous line scale anchored on the left with
“none” of the attribute and on the right with “strong” represented by a reference standard consisting on an emulsion of 0.25%
anacardic acid in water. As a part of the training program judges rated three cashew nut samples in three replications.
Performance of each judge was evaluated by ANOVA for each attribute, with sample and replicate terms. Judges had to show
good discriminative power (p<0.30), good reproducibility (p>0.05) and consensus to the panel judgement (Damasio & Costell,
1991).
Sensory analysis. Samples were presented to judges monadically in three replications. All of them were randomly coded
with three digit numbers. Individuals were presented with four nut samples and were asked to eat two at a time.
Statistical analysis. Data were submitted to ANOVA with industrial unit, roasting and their interaction as effect terms. For
the sensory experiment judges were treated as blocks. The Duncan test was used to compare means. Analytical and sensory
data were also submitted to Pearson correlation analysis. All statistical analysis were performed by SAS software.
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Results and Discusión
Table 1. Cashew nuts collected at Fortaleza, 2001.
The analysis of variance showed
Sample
Industrial unity
Decorticating process Roasting
significant effects of the industrial unity
1
Unity A
Semi-mechanized
Natural
and roasting for anacardic acids and
2
Unity A
Semi-mechanized
Roasted
3
Unity B
Semi-mechanized
Natural
both burning sensation attributes
4
Unity B
Semi-mechanized
Roasted
(p<0.01). The interaction industrial
5
Unity C
Mechanized
Natural
unity x roasting showed no significant
6
Unity C
Mechanized
Roasted
effect. Evaluation of the means (Table
7
Unity D
Mechanized
Natural
2) showed that industrial units that use
8
Unity D
Mechanized
Roasted
semi-mechanized decorticating process
(A and B) had higher anacardic acid
Table 2. Duncan test results for anacardic acids content and burning
content than units using the mechanized
sensation attributes, for cashew nuts samples.
process. In general, cashew nuts from
Source variation/ treatment Anacardic
Burning sensation
semi-mechanized process also showed
acids
higher scores for the burning sensation
mg/100g
During mastication After ingestion
attributes. In fact, this correlation was
Industrial unity
confirmed by the high significance level
Unity A (semi-mechanized) 125.10 a
0.77 a
0.95 a
obtained between anacardic acid
Unity B (semi-mechanized) 69.44 b
0.55 ab
1.04 a
Unity C (mechanized)
49.92 c
0.23 b
0.47 b
content and burning during mastication
Unity D (mechanized)
27.65 d
0.23 b
0.48 b
(p=0.003). The linear regression
Roasting
equation is Burning = 0,0062 x
Natural
78.31 a
0.62 a
0.99 a
Anacardic + 0,0543. Burning after
Roasted
57.74
b
0.22
b
0.48
b
ingestion did not correlate to anacardic
acid, but showed a high positive
correlation to burning during mastication (p=0.0002), indicating that measuring this latter attribute is probably enough to
characterize the sensory sensation elicited by the vesicant properties of anacardic acids. Nuts from the mechanized process
were expected to show higher contamination by CNLS phenolic lipids, due to the contact with the shells at the decorticating
centrifuge output. But the methodology used in the present work is specific to determine anacardic acids. Natural, cold
extracted CNSL, as exuded in the semi-mechanized process, consists mainly of 90% anacardic acid (6-alkil salicylic acid) and
10% cardol (3-alkyl resorcinol). However during the mechanized process, the liquid undergoes high heat treatment, and the
anacardic acid is decarboxylated, being converted to cardanol (3-alkyl phenol), remaining only minor amounts of anacardic
acid. So we cannot state that semi-mechanized process causes higher contamination, but is clear that the decorticating step is
critical regarding to cashew nuts contamination by CNSL. It was observed that within industrial units that use the same
decorticating process there was always one with higher contamination (A>B, C>D). The roasting procedure resulted in an
average reduction of 26% in the cashew nuts anacardic acid level, corresponding to a significant reduction in the burning
sensation intensity.
Literature Cited
Strocchi, A.; Lercker, G. 1979. Cardanol in germ and seed oil extracted from cashew nuts obtained by the oltremare process. J. Amer. Oil
Chem. Soc. 55: 616-619.
Agostini-Costa, T.S; Jales, K.A.; Abreu, L.N.; Rossetti, A.G.; Silveira, E.R. 2003. Determination of anacardic acids in cashew apples
(Anacardium occidentale L.). Rev. Bras. Pl. Med. 5:77-81.
Damasio, M.H.; Costell, E. Análisis sensorial descriptivo: generación de descriptores y seleción de catadores. Rev. Agroq. Techn.
Alimentos, v.31, n.2, p.165-178, 1991.
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