Influence of processing methods on the bioavailability of beta-carotene in selected foods

Abstract

The study entitled "Influence of processing methods on the bioavai labil ity of 13-carotene in selected foods" was carried out with the objective to envisage the current consumption pattern of 13-carotene rich foods and to assess the influence of selected processing techniques on the bioavailability of 13-carotene. The consumption pattern of carotene rich foods was elucidated by a dietary survey conducted among fifty urban and fifty rural homemakers from Thiruvananthapuram district. Personal profile of the respondents indicated that majority were middle aged Hindu women belonging to nuclear middle income families Most of the families were small sized, with less than five members. The monthly food expenditure pattern indicated that urban families spent more amount on food compared to rural households. With regard to frequency of use of 13-carotene rich foods, locally available green leafy vegetables like agathi, drumstick leaves and chck kurrnanis were consumed more by rural families than urban as these items were available from their homesteads. Amaranth (red and green) though purchased mostly from markets and shops was preferred equally by households of both areas. Moreover, urban families were found to prefer conventional vegetables like carrot, yam, pumpkin and fruits like dates which arc readily accessible from the markets. Cluster beans a low cost 13- carotene rich vegetable was preferred by rural families. Seasonally available jack fruit and locally available papaya were observed to be more frequently consumed by rural households, while mango, orange and tomato were used in a similar frequency rate by both the groups. The ten commonly consumed 13-carotene rich vegetables identified through survey included green leafy vegetables like agathi, amaranth (red and green), drumstick leaves and chekkurmanis, other vegetables and fruits like carrot, yam, cluster beans, pumpkin and tomato (ripe). Daily meal pattern of the selected rural and urban families assessed by recallmethod revealed that the p-carotene content of the diets of most of the families were inadequate, as it could meet only less than 75 per cent of their RDA. Meanwhile a small group were able to obtain fJ-carotene even above 100 per cent of RDA. The dietary adequacy of p-carotene of the daily diet of homemakers were specifically studied as women are more susceptible to poor nutrition for several reasons. It was found that majority of women (both urban and rural) had diets deficient in fJ-carotene and only a small group had satisfactory intake of this nutrient meeting 83-100 per cent of RDA. Also very few homemakers were observed to meet adequate levels of carotene from their diets. Enquiry on the processing practices adopted for cooking p-carotene rich vegetables revealed that sauteing, boiling / stewing and pressure cooking were the commonly employed methods. The use of pressure cooker was however more common among urban families. Similarly the use of modern gadget microwave was also found only among very fewurban households. Following the standardised procedures of cooking, the ten p- carotene rich vegetables were processed and subjected to bioavailability study. Bioavailability analysis of selected p-carotene rich foods highlighted that processing treatments of vegetables namely sauteing, boiling and stewing released more bioavailable form of p-carotene. At the same time processing techniques in which a high temperature was employed as in the case of pressure cooking and microwave cooking, the bioavailability of ~-carotene was found to be lower than the same unprocessed vegetables. With respect to all green leafy vegetables studied, the bioavailability percentage was .maxirnum when cooked by sauteing. Processing influence on the remaining vegetables revealed that sauteing, boiling and stewing were better methods for enhanced bioavailability or ~-carotel1e compared to their other processed forms and raw samples experimented in this study. Boiling was observed for carrots, pumpkin and green amaranth. Similarly for yam both sauteing and stewing was found to be the ideal methods, while for tomato stewing was the best method since these treatments improved ~-carotene bioavailability; even for cluster beans. sauteing was recorded as the best cooking practice. To bring the observations to a nut shell, it was concluded that certain processing treatments such as sauteing, stewing and boiling were found to be positively influencing ~-carotene bioavailability from vegetables and fruits. Sauteing was proved to be an outstanding and superior processing method enhancing ~-carotene bioavailability, followed by boiling and stewing. Study also highlighted the variations in bioavailability status or ~-carotene from different plant foods. It was observed that the percentage bioavailability of ~-carotene from fruits like tomato and pumpkin was high followed by carrot, yam and cluster beans. Green leafy vegetables eventhough labeled as the richest source of ~-carotene, bioavailability of this nutrient was comparatively low.