Fig 1.
Criteria for assessed ripeness of bananas.
Fig 2.
Results for control materials (CC) analyzed with banana samples from the ripening study (blue) and the retail study (red). EG = enzymatic-gravimetric method (AOAC 991.43) [14]; mEG = modified enzymatic-gravimetric method [16]; HMWDF = high molecular weight dietary fiber (insoluble dietary fiber and soluble dietary fiber precipitate) and LMWSDF = low molecular weight soluble dietary fiber (AOAC 2011.25) [16]. Circle (○) = Fiber Vegetable CC, Square (□) = NIST SRM®3233 Breakfast Cereal, X = Starchy Vegetable II CC (see Materials and Methods); reference ranges (target ± uncertainty, g/100g) for NIST SRM® 3233 [30]: EG total fiber, 7.8–10.2; mEG total fiber, 9.2–14.6; HMWDF, 6.4–12.0; LMWSDF, 1.8–4.2; fructose, 0.42–1.20; glucose, 0.68–1.40; sucrose, 12.67–14.17; maltose 0.37–0.55. Assayed maltose was <0.15 g/100g in all banana samples.
Table 1.
Summary of results for commercial reference materials and control materials analyzed with samples from ripening study and retail study samples.
Fig 3.
Changes in content of sugars, starch, and dietary fiber in a single lot of bananas assayed at different stages of ripeness.
Values shown are the mean ± standard deviation for three samples of each ripeness, each consisting of a homogenate of three to five bananas, with ripeness assessed according to the criteria in Fig 1.
Fig 4.
Dietary fiber, starch, and sugars in retail samples of bananas of the same ripeness (defined as in Fig 1).
Data points in the same color are from the same sample (i.e., same hand(s) from the same lot, supplier, purchase point/time), where a portion of the bananas were allowed to ripen further, and the red symbols (◇) denote the ripening study samples. EG = enzymatic-gravimetric method (AOAC 991.43) [14]; mEG = modified enzymatic-gravimetric (“McCleary”) method (AOAC 2011.25) [16]. ─ mean, with error bars showing two times the standard error. Maltose was <0.5 g/100g in all samples.
Table 2.
Mean and range for dietary fiber, sugars, starch, and proximate composition of retail samples of bananas of different ripeness (unripe bananas were not analyzed in retail samples).
Fig 5.
Mean energy content of bananas of different ripeness in the retail study, calculated from proximate data (Table 2) using either the specific or general Atwater factor for carbohydrates by difference (3.6 and 4 and kcal/g, respectively) [87], with and without subtracting EG fiber or mEG fiber (see Table 2) from total carbohydrates by difference before applying the general factor.
Error bars show the range for 6 samples at each stage of ripeness.