The nutrient content of whole and semi-processed Baobab (Adansonia digitata) fruit and seeds Brian Wood October 30th, 2020 Summary This short report describes field and lab experiments used to determine the energy content of 1 kg of baobab fruit in two forms: 1) whole unprocessed fruit and 2) semi-processed fruit that has had the outer shell removed. These goal of this report is to permit researchers to accurately estimate the energy content of baobab fruit as weighed during anthropological research with Hadza hunter-gatherers of northern Tanzania. The estimates assume that the seed of the baobab is being cracked open and the “nutmeat” consumed, as is customarily done by Hadza. The baobab fruit is an economically important wild plant food in many parts of Africa, and global demand for the fruit is growing, and thus these results have value for a variety of audiences. Based on the analyses reported below, I estimate that 1 kilogram of whole unprocessed baobab represents an expected energy value of 1057 kcal. One kilogram of semi-processed baobab has an expected energy value of 1791 kcal. Incorporating the relative fraction of baobab that is brought to camp by Hadza in these two forms, I estimate that 1 kilogram of field-weighed baobab has an average energy content of 1339 kcal, or 1.339 kcal / gram. Methods and Results Murray et al (2001) published nutritional analyses of Hadza-acquired baobab. These analyses were done on the processed seed meat (“ground seeds”) and the fruit pulp, and thus represent the nutrient value of the baobab after processing. However, the food weights that researchers working with the Hadza measure in the field are made upon either whole baobab pods, or semi-processed baobab fruit which has had the shell removed. It is necessary to subtract from our field weights the inedible fractions: the weights of the outer baobab shell, the discarded interior fibers, and the hard shells of the seeds. BW collected measures of these inedible fractions in the field in Tanzania (2019) and in the Harvard Nutritional Laboratory (2010) that allow us convert baobab field weights to caloric values (Table 1). Pulp & seed Fruit Whole dry Shell & Pulp & seeds Shell & fiber Seed Seed fraction Pulp fraction Seed fraction of Pulp (g) fraction of Location Sample (g) fibers (g) (g) fraction of whole (g) of whole of whole pulp & seeds whole 1 102 39 63 0.38 20 43 0.42 0.20 0.62 0.68254 Harvard 2 73 34 39 0.47 11 28 0.38 0.15 0.53 0.717949 Harvard 3 125 47 77 0.38 23 54 0.43 0.18 0.62 0.701299 Harvard 4 86 35 51 0.41 0.59 Tanzania 5 68 17 51 0.25 0.75 Tanzania 6 81 32 49 0.4 0.6 Tanzania 7 69 29 40 0.42 0.58 Tanzania 8 72 34 38 0.47 0.53 Tanzania Mean 84.5 33.38 51 0.4 18 41.7 0.41 0.18 0.6 0.7 SD 19.86 8.53 13.41 0.07 6.24 13.05 0.03 0.03 0.07 0.02 TABLE 1. Weight of baobab fruit components The shells of baobab seeds are also inedible and must be subtracted from field weights. At the Harvard Nutritional Laboratory, in 2010, BW calculated the fraction of weight of whole seeds that is inedible outer shell (Table 2). Seed Angiosperm Shell fraction of Nutmeat fraction N seeds Whole seed (g) Shell (g) Sample ('nutmeat') (g) seed weight of seed weight 1 10 5.8 3.4 2.4 0.59 0.41 2 10 4.9 3 1.9 0.61 0.39 Mean 10 5.35 3.20 2.15 0.60 0.40 SD 0 0.64 0.28 0.35 0.01 0.01 TABLE 2. Mass of baobab seeds, seed shells, and nutmeat from samples at Harvard Nutritional Laboratory We next couple these measures of the inedible fractions of baobab with the nutrient values reported by Murray et al. (2001). After subtracting the weight of the baobab fruit outer shell and the seed shells and discarded fibers, the expected caloric value of 1 kg of whole unprocessed baobab is 1057 kcal, or 1.057 kcal/gram (Table 3). Item Mass (g) Kcal Fat g Carb g Protein g Notes Whole Wet Wt. (WWW) 1000 -- -- -- -- Approx. 10 baobab fruit Moisture (4.75%) 47.5 -- -- -- -- 4.75% moisture (Murray et al. 2001) Whole Dry Weight (WDW) 952.5 -- -- -- -- Shell and discarded fibers (dry) 381 -- -- -- -- Fruit shell and fibers are 40% of WDW (Table 1) Whole seed (dry) 390.53 -- -- -- -- Seed is 41% of WDW (Table 1) Pulp is 18% of WDW (Table 1); 203 kcal / 100 g dry weight (Murray et al. Fruit pulp (dry) 171.45 348.04 1.2 79.9 4.29 2001); 46.6 g of carb (starch and simple sugar) per 100 g dry weight (Murray et al. 2001); 0.7 g fat per 100 g dry (Murray et al. 2001) Nutmeat is 40% of whole seed (Table 2); 454 kcal / 100 g dry weight (Murray et al. 2001); 29.3 g of fat per 100 g dry nutmeat; 11.2 g of carbs per 100 g dry Seed nutmeat (dry) 156.21 709.19 45.77 17.5 56.7 weight (Murray et al. 2001); 36.3 g protein per 100 g dry weight (Murray et al. 2001) Seed shell (dry) 234.32 -- -- -- -- Shell of seed is 60% of whole seed (Table 2) Total 1000 1057.23 46.97 97.4 60.99 TABLE 3. Nutrient content of 1 kilogram of whole baobab fruit The Hadza also bring to camp baobab in a semi-processed form. This is baobab fruit pulp after the outer shell has been removed. Embedded in the fruit pulp are unprocessed seeds. 1 kg of baobab in this state results in 1.79 kcal / gram (table 4). Item Weight (g) Kcal Notes Whole Wet Wt. (WWW) 1000 -- Approx. 16-17 Baobab Pods Moisture (5%) 47 -- 4.7% moisture (Murray et al. 2001) Whole Dry Wt. (WDW) 953 -- Whole Seed (Dry) 667.1 -- Whole seed is 70% of WDW (Table 1) Fruit Pulp is 30% of WDW (Table 1), 203 Fruit Pulp (Dry) 285.9 580.38 Kcal/100g dry weight (Murray et al. 2001) Seed Angiosperm is 40% of Whole Seed (Table Seed nutmeat 266.84 1211.45 2). 454 Kcal / 100g dry weight (Murray et al. 2001) Shell of Seed (Dry) 400.26 0 Shell of Seed is 60% of Whole Seed Total 1000 1791.83 TABLE 4. Nutrient Content of 1 kg of Baobab Fruit with Shell and Fiber Removed To calculate a weighted average of baobab nutrient composition that correctly considers the state of the fruit when weighted, we now analyze Hadza food returns. For this analysis, we examine food returns collected from 2005 and 2016, in 17 different Hadza camps with data collection supervised by the author. These data cover 371 observation days. In these camps, we noted the condition of the baobab that was taken to our research station to be weighed, indicating whether the baobab was in a whole pod form or in a processed state in which the outer husk had been removed. In total, 766.06 kg were brought in the whole pod condition, and 476.70 in the semi-processed state. This indicates that 0.616 of the baobab are in the “whole” form and 0.384 in the “semi-processed” form. We next use the fraction whole pod vs. fraction semi-processed and the nutrient data presented in tables 3 and 4 to create a weighted average for the caloric value for field-weighed baobab. 1 kg of field-weighed baobab will on average represent: 616 grams of whole baobab which has a caloric value of 651 (1057*.616) and 384 grams of processed baobab which has a caloric value of 688 (1791.83*.384). In total, this results in 1 kilogram of field-weighed baobab having an energy content of 1339 kcal, or 1.339 kcal / gram. Citation Murray, S. S., Schoeninger, M. J., Bunn, H. T., Pickering, T. R., & Marlett, J. A. (2001). Nutritional composition of some wild plant foods and honey used by Hadza foragers of Tanzania. Journal of food composition and analysis, 14(1), 3-13..