BACKGROUND: Texture is a major quality parameter for the acceptability of canned whole beans. Prior knowledge of this quality trait before processing would be useful to guide variety development by bean breeders and optimize handling protocols by processors. The objective of this study was to evaluate and compare the predictive power of visible and near infrared reflectance spectroscopy (visible/NIRS, 400-2498 nm) and hyperspectral imaging (HYPERS, 400-1000 nm) techniques for predicting texture of canned black beans from intact dry seeds. Black beans were grown in Michigan (USA) over three field seasons. The samples exhibited phenotypic variability for canned bean texture due to genetic variability and processing practice. Spectral preprocessing methods (i.e. smoothing, first and second derivatives, continuous wavelet transform, and two-band ratios), coupled with a feature selection method, were tested for optimizing the prediction accuracy in both techniques based on partial least squares regression (PLSR) models.

To facilitate direct harvest, preharvest herbicide applications are used to desiccate weeds and to accelerate and promote uniform dry bean (Phaseolus vulgaris L.) maturation. Field trials were conducted near Richville, MI, in 2013 and 2014 to evaluate the effects of preharvest herbicide treatments on desiccation, yield, and canned black bean quality and color. Three black bean cultivars, Zorro, Eclipse, and Zenith, were planted on two different dates in each of 2 yr. Three preharvest herbicide treatments, paraquat, glyphosate, and saflufenacil, were applied at a standard (pods = 80% yellow) and an early (pods = 50% yellow) application timing. A nontreated control was established for each cultivar. Differences in black bean desiccation were greatest 3 d after treatment (DAT), with paraquat and saflufenacil showing the quickest desiccation at the early application timing. By 7 DAT, desiccation for most preharvest treatments was >95%. Saflufenacil applied at the early timing reduced yield by as much as 55% compared with the nontreated control. Yield was generally not affected when preharvest herbicide treatments were applied at the standard application timing. Black bean cultivar influenced canned bean color retention (Zenith > Zorro > Eclipse). Preharvest herbicide treatments reduced color retention when applied at the early application timing; glyphosate reduced color retention by as much as 24%. Because of variability in bean maturation rate within a field, preharvest herbicide treatments need to be applied as close to physiological maturity as possible to minimize yield losses and maintain color retention of canned black bean.