ARCHIVOS LATINOAMERICANOS DE NUTRICIÓN Vol. 62 Nº 3, 2012 Órgano Oficial de la Sociedad Latinoamericana de Nutrición Estimation of glycaemic index of peach palm (Bactris gasipaes) cooked fruits and chips, and pitahaya (Hylocereus spp.) pulp Gin Jiménez, Georgina Gómez, Ana M. Pérez, Adriana Blanco-Metzler Escuela de Medicina, Universidad de Costa Rica. Centro Nacional de Ciencia y Tecnología de Alimentos (CITA). Universidad de Costa Rica. Instituto Costarricense de Investigación y Enseñanza en Nutrición y Salud (INCIENSA). San José, Costa Rica SUMMARY. The glycaemic index (GI) is a physio- RESUMEN. Estimación del índice glicémico del fruto cocido logical measure of a food’s potential to increase pos- y de chips de pejibaye (Bactris gasipaes) y de la pulpa de pi- tprandial blood glucose, as compared to the effect tahaya (Hylocereus spp.). El índice glicémico (GI) es una medida produced by food taken as reference, such as glucose fisiológica del potencial de un alimento para incrementar la glu- or white bread. Currently researchers and consumers cosa sanguínea, en comparación con el efecto producido por un are interested in low GI foods, since their consump- alimento de referencia, tal como la glucosa o el pan blanco. Los tion is associated with better weight control and re- investigadores y consumidores tienen interés en los alimentos de duced risk of incidence of chronic diseases, like bajo GI, dado que su consumo está asociado con un mejor control diabetes. In the present study, the GI value for peach del peso corporal y una reducción del riesgo de enfermedades cró- palm cooked fruit, peach palm chips and pitahaya nicas como la diabetes. En el presente estudio se determinó el pulp was estimated. The methodology established by valor de GI del fruto cocido de pejibaye, de los chips horneados the FAO / WHO for determining the GI of food was de pejibaye y de la pulpa de pitahaya. Se seleccionaron 12 volun- used. A total of 12 healthy, non-smoking volunteers tarios, aparentemente sanos, no fumadores, los cuales consumie- were selected and they ingested the fore mentioned ron los alimentos evaluados y el alimento de referencia (pan foods on different occasions, in 25 g portions of avai- blanco), en una porción que contuviera 25 g de carbohidratos dis- lable carbohydrates, after 12-14h overnight fast. ponibles, después de un período de ayuno de 12-14 h. Los niveles Blood glucose levels were measured in 30 min inter- de glucosa en sangre fueron medidos en intervalos de 30 min vals up to 120 min after ingestion. Average GI value hasta 120 min después de la ingesta. Se obtuvo un valor promedio was 48 ± 11 for the pitahaya pulp and 35 ± 6 for the de GI de 48 ± 11 para la pitahaya y de 35 ± 6 para el pejibaye co- peach palm cooked fruit, which may be classified as cido, los cuales pueden ser clasificados como alimentos de bajo low glyceamic index foods. The GI of peach palm índice glicémico. El valor de GI de los chips de pejibaye fue de chips was 60 ± 7, corresponding to a food with a mo- 60 ± 7, lo que corresponde a un alimento de GI moderado. Se en- derate GI. The processing for producing the chips contró que el procesamiento para la obtención de los chips pro- caused an increase in the GI value when compared to dujo un aumento en el valor del GI, en comparación con el the cooked fruit, probably because the stages of mi- obtenido para la fruta cocida, probablemente debido a que las eta- lling, moulding and baking promote availability of pas de molienda, moldeo y horneo favorecen la disponibilidad del starch during hydrolysis by the digestive enzymes. almidón para su hidrólisis por parte de las enzimas digestivas. Key words: Glycaemic index, peach palm, pitahaya, Palabras clave: Indice glicémico, pejibaye pitahaya, glucosa san- blood glucose, functional foods guínea, alimentos funcionales. INTRODUCTION (4). In contrast, the inclusion of low GI foods in a diet can help control blood glucose (5). Low GI foods, by virtue of The glycaemic index (GI) is a concept that the slow digestion and absorption of their carbohydrates, was introduced in 1981 by Jenkins et al. in order produce a more gradual rise in blood sugar and insulin le- to quantify the glycaemic response to carbohy- vels, and are increasingly associated with health benefits drates in different foods (1). Recent studies show (6). In Costa Rica, there is a variety of fruits which have re- that consumption of high GI foods is associated cently attracted the interest of national and international with a greater risk of type 2 diabetes mellitus (2), markets, being widely studied in order to identify different cardiovascular disease (3), and certain cancers nutritional and functional components which provide health 242 ESTIMATION OF GLYCAEMIC INDEX OF PEACH PALM (BACTRIS GASIPAES) 243 benefits, such as the antioxidant activity in the case of palm fruits (red-orange peel) were harvested in Tucu- the pitahaya (Hylocereus spp.) and the fibre and beta- rrique (Jiménez, Cartago province, at an altitude of carotene contents of peach palm fruits (Bactris gasi- 760 m.a.s.l). They were washed with water, and disin- paes) (7-9). fected with sodium hypochlorite (200 ppm) for 5 min. Currently, there is little information about GI va- They were cooked by immersion in boiling water (96 lues for tropical fruits, such as banana, pineapple, º C for 30 min) and stored frozen (-20 º C) until use. lychee papaya, mango, breadfruit, and sapote (5). For consumption, the peach palm fruits were thawed There is no information regarding the effects that at room temperature, peeled, and deseeded. physicochemical changes occurring during processing Peach palm chips: Peach palm whole cooked fruits could have on the GI values of tropical fruits, as is the were ground with skin attached to obtain a paste that case in the production of peach palm chips. The main was stored at -20 º C until use. Dough thawed at room objective was to estimate the GI of peach palm (Bac- temperature and was mixed with water (6%) and salt tris gasipaes) cooked fruits, peach palm baked chips (1.2%) before being moulded into slices which were and pitahaya (Hylocereus spp.) raw pulp, and to esta- 2 mm thick and 6 cm in diameter. The chips were blish the changes on the GI value during processing baked (oven Dictate, 65X4516 HF model) at 125 º C of the peach palm fruit. for 25 min to obtain a final product weight of appro- ximately 3.6 g per slice or chip. MATERIALS AND METHODS TABLE 1 Characteristics of subjects participating in the study. Selection of subjects: 12 healthy, non- smoking, normal weight, male and female vo- Parameter General Male Female lunteers, aged between 18 and 51 years, were n 12 5 7 selected (Table 1). The volunteers showed no Age (years) 33 ± 11 27 ± 11 36 ± 11 family history of diabetes or food allergies, Weight (kg) 64.5 ± 8.1 67.7 ± 7.7 62.2 ± 8.1 were not taking medication, and were not fo- Height (m) 1.65 ± 0.08 1.72 ± 0.05 1.60 ± 0.05 llowing any weight loss diet. All volunteers were instructed to not perform strenuous exer- B.M.I (kg/m2) 23.8 ± 2.8 22.9 ± 2.4 24.4 ± 3.0 cise, drink alcohol, or eat an unusual amount Systolic blood pressure (mm Hg) 117 ± 8 121 ± 8 113 ± 8 of food the night before the study. None of the Diastolic blood subjects were taking medication. According pressure (mm Hg) 74 ± 7 76 ± 8 73 ± 6 to Aston et al. (10) 25 g portions of available Fasting blood glucose carbohydrates of each food were consumed baseline (mg/dl) 85 ± 3 88 ± 3 84 ± 3 with 300 mL water after a 12-14h overnight Mean ± S.D; BMI: Body Mass Index fast. The subjects were requested to consume the foods within 10 min. A single venous blood sample was taken in the fasted state and at 30, 60, 90 and 120 min after eating the food. Each sample was analysed in duplicate according to the FAO / WHO (11) protocol. The study was approved by the institutional Bioethics Committee involved (University of Costa Rica, San José, Costa Rica, Project No. 422-A7-049) and subjects gave written, infor- med consent. Test foods Figure 1 summarizes the process flow for preparing each studied food. Peach palm cooked fruits: Mature peach FIGURE 1. Process of food preparation for the study. 244 JIMÉNEZ et al. Pitahaya pulp: The fruit was washed with water dual, divided by the value of AUC’s increase of and disinfected with sodium hypochlorite (200 ppm) glycaemia for the reference food for each individual for 5 min. The fruit was peeled and then the pulp was multiplied by 100, and then multiplies by 0.7 to obtain removed, chopped, and stored frozen (-20 ° C) until the GI value with glucose as the reference food (5). further use. The volunteers were allowed to add sucra- The GI was expressed as means ± S.E. for the indivi- lose (Splenda ®) ad libitum. duals participating in the study for each food (n = 12 Control (white bread): As a reference a sliced white for bread and n = 8 for pitahaya pulp, and peach palm wheat bread was used (Breddy ® brand). The crusts cooked fruits and chips). An analysis of variance was were removed; the bread was packed in plastic bags performed to compare the blood glucose concentration and stored at 0 °C until use. significance between times (0, 30, 60, 90, 120 min) Chemical and nutritional analyses for each food.