Journal of the Science of Food and Agriculture J Sci Food Agric 79:291–299 (1999) Kinetics of moisture loss and fat absorption during frying for different varieties of plantain Alberto Diaz1, Gilles Trys tram2, Olivier Vitrac3,4, Dominique Dufour3,4, Anne-Lucie Raoult-Wack3*. 1 UNIVALLE, Food Science and Technology Department, AA 25360, Cali, Colombia 2 ENSIA, Food Proces s Engineering Department, 1 Av des Olympiades , 91744 Mas s y cedex, France 3 CIRAD-AMIS 73 rue JeanFrancÓ ois Breton, BP 5035, 34032 Montpellier cedex, France 4 CIAT, AA 6713, Cali, Colombia Abstract : This study compares the behaviour of four varieties of green plantain at their initial stage of maturity during the frying process. A variety traditionally used for the manufacture of thin plantain chips (Dominico Harto n commun) and three other varieties found in Latin America (Bouroukou, Bluggoe and FHIA 21) were used. The varieties were characterised by measuring initial moisture content, total sugar content, reducing sugar content, starch content and apparent density. Moisture loss and fat uptake kinetics during frying were assessed at diþ erent temperatures (145, 165 and 185ÄC). With all four varieties, the time required to produce a ünal moisture content of 40 g kg—1 (wb) was about 90 s at 165ÄC and 185ÄC. Use of a lower temperature (145ÄC) extended the processing time to 150 s. On the other hand, temperature had very little eþ ect on fat content, which proved to be essen- tially determined by the variety of plantain. Fat content for ünal water content levels of 40 g kg—1 (wb) ranged from 300 g kg—1 (wb) for Bouroukou to 450 g kg—1 (wb) for Bluggoe regardless of the processing temperature. ( 1999 Society of Chemical Industry Keywords: plantain, frying, varieties, composition, kinetics, moisture loss, fat uptake, palm oil. INTRODUCTION country’s annual production of approximately 2.5 The world snack food market is currently expanding million tonnes primarily supplies the home market,4 rapidly.1 For example, the snack food market in the with only about 200 000 tonnes per year being USA, worth US$ 25 billion in 1987, has grown by exported to the American market.5 A survey con- US$ 10 billion a year over the last ten years.2 Alarge ducted using a sample of 170 consumers residing in part of this market consists of chips or fried products Cali (Colombia’s third-largest city), with very varied using starch-based raw materials (roots, tubers, standards of living, revealed that 99% of households bananas and plantains). Such products are obtained who prepared home-fried products used plantains, by cutting the raw material into üne slices or paral- 92% of the population surveyed prepared patacones lelepipeds, initially a few millimetres thick, then more than once a week, while 43% bought industrial frying them in vegetable oil for a few minutes at high patacones on a regular basis. This survey also temperature (130 to 180¡C at atmospheric pressure). revealed that 87% of consumers of industrial pata- Frying is a very widespread method of plantain cones would increase their consumption if product chip production, both for local consumption and for quality were improved.6 export. In Europe, banana and plantain chips Despite the volume of fried products consumed (primarily imported from South-East Asia) are con- throughout the world, aspects related to management sumed in cocktail mixtures and in breakfast cereals. of the frying process have up to now been the subject Plantain chips are regarded as a popular consumer of relatively little research, compared to other pro- product in Africa.3 ‘Patacones’ and ‘tajadas’, pieces duction processes. Research into frying has essen- of green plantain fried in coarse or üne slices cut tially concentrated up to now on oil deterioration lengthways or crossways, are very common in Latin kinetics.7 Little attention has been paid to the eþect America. The latter are produced on a small scale of the variability of the raw material on its frying either at home or by street vendors or are manufac- behaviour and the physicochemical properties of the tured industrially. One of the largest producers of ünal product.8 There are nevertheless numerous ref- plantains in Latin America is Colombia, which has erences to the production of fried plantain chips in about 400 000 hectares under cultivation. The Latin America, Asia and Africa. The literature * Corres pondence to: Anne-Lucie Raoult-Wack, CIRAD-AMIS, 73 rue JeanFrancÓ ois Breton, BP 5035, 34032 Montpellier cedex, (Received 19 September 1997; revis ed vers ion received 2 April France 1998; accepted 12 June 1998) ( 1999 Society of Chemical Industry. J Sci Food Agric 0022-5142/99/$17.50 291 A Diaz et al reports that plantain chips are produced in Vene- The plantains were peeled by hand. The pulp was zuela,9 Costa Rica,10 Honduras,11 Colombia, sliced into üne rings, 2 ^ 0.1 ] 10~3 m thick, using a Ecuador,12 Puerto Rico,13 Brazil,14 the mechanical slicer (SEDALIA MO 65301, Rival Philippines15h18 Indonesia,19 Malaysia20,21 MFG Company, USA) with an adjustable cutting India,22h25 Nigeria,3,26 Cameroon27 and the Ivory disc. The discs were measured with a sliding calliper Coast.28 It is difficult, however, to formulate general and any incorrectly sliced were rejected. rules as to the suitability of diþerent varieties on the The discs were pre-treated before each trial, using basis of these studies, since they use diþerent frying the protocol deüned by Diaz et al,12 then dried on conditions. absorbent paper. Each test sample consisted of a Only two varieties of triploid AAB plantain are mixture of rings selected from several plantains of currently used for industrial frying in Colombia: the same variety and taken from the same hand. ‘Harto n commun’ (Musa paradisiaca Linneo) and ‘Dominico Harto n commun’ (Musa paradisiaca Frying equipment Simmonds). The frying trials were conducted using a semi- The purpose of the present study was to compare industrial electric fryer (AFI FT/4, Italy). The the behaviour of four varieties of green plantain: one frying tank was parallelepiped-shaped and made of of the two varieties traditionally used in Colombia, stainless steel. Its dimensions were: length ‘Dominico Harto n commun’, and three other vari- 300 ] 10~3 m; width 150] 10~3 m; height eties found in Latin America. The study aimed at 200 ] 10~3 m. The bath had an eþective volume of characterising the diþerent varieties (apparent 5 litres. It was heated by an 1800 W 26 ) electrical density, total sugar content, reducing sugar content, resistor. The resistor had an area of 0.046m2,iea starch content, moisture content) and the frying surface ýux of 82.8 W m~2, and was located behaviour of these varieties in terms both of changes 35 ] 10~3 m above the bottom of the tank. in moisture and fat content and of mass yield after There was a submerged agitator shaft in the centre processing. of the tank. The shaft was ütted with two ýat tur- bines arranged one above the other at a distance of MATERIALS AND METHODS 50 ] 10~3 m, with the lower one located just above Plantain preparation the electrical resistor. Each turbine had six blades Green plantains from the entire coþee-growing (external diameter 60 ] 10~3 m, blade height regionwereusedinthisstudy.Theyweresupplied 12 ] 10~3 m, blade width 15] 10~3 m). Frying by CORPOICA (Centro Experimental EL operations were performed with the agitator shaft AGRADO, situated 1320 m above sea-level). Four rotating at a speed of 18.8 rad s~1. varieties of plantain were chosen, taking into account Two removable holders were submerged in the traditional use, availability during the year, size of tank, one on either side of the agitator shaft. Each bunch, size of fruit, agronomic yield and resistance held three hinged stainless steel grids (length to black Sigatoka (Mycosphaerella üjiensis). The vari- 130 ] 10~3 m, width 90] 10~3 m, thickness eties tested were selected according to the following 10 ] 10~3 m) placed horizontally and 10 ] 10~3 m criteria: apart. The grids had a porosity of 81%. Dominico Harto n commun (triploid AAB, Musa The temperature of the frying bath was deter- paradisiaca Simmonds): variety traditionally used for mined by simultaneously measuring the tem- the production of fried chips, available throughout peratures shown by three K-type thermocouples the year ; (CCM-1-250-K, Mesurex, France). The average of Bouroukou no. 1 (triploid AAB, Musa paradisiaca the three temperatures was termed the ‘reference Linneo): variety of African origin, adapted to the cli- temperature’. The thermocouples were placed along matic conditions of Colombia, with very large fruit ; the tank at mid-depth. They were connected to a Bluggoe (triploid ABB, Musa paradisiaca Bluggoe): data logger (CR10X, Campbell Scientiüc, Great variety traditionally regarded as a cooking plantain, Britain) and a control panel interface (CR10KD key- with a more attractive market price; board, Campbell Scientiüc, Great Britain). The time ‘FHIA 21’ (tetraploid AABB hybrid, Musa para- base for temperature data acquisition by the com- disiaca of the Dominico group): developed in Hon- puter system was 2.72] 10~3 s. The program then duras and used in the industrial frying of patacones, regulated the temperature by sending an electric resistant to black Sigatoka, with an extremely high current to the heating resistor for periods of 0.25s. agronomic yield.29 The bunch of plantains of each variety was harvested Conduct of the trials the day before the trials, about 112 days after ýower- Frying was carried out using reüned palm oil, which ing, and stored in a temperature-controlled chamber was renewed every day.