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Spent coffee grounds (SCG) constitute the main residue generated in the coffee-based food industry and exhibit potential use as sources of antioxidants. The aim of this work was to investigate the effects of light and dark roasting on the properties of SCG and its use in muffin production. Phenolics, antioxidant activity, caffeine, trigonelline, and chlorogenic acid were higher in SCG produced by light roasting; thus, this sample was selected for use as an ingredient in the production of muffins. The compromised acceptance threshold (CAT) and hedonic rejection threshold (HRT) of muffins added by SCG were evaluated for the first time for this food waste. SCG addition from 1.72% resulted in a CAT and a SCG addition from 85.82% in an HRT. The use of SCG in muffins is feasible; however, it is recommended that the maximum amount added is close to that corresponding to CAT to reduce the likelihood of product rejection.

The consumer rejection threshold (RjT) method was applied to determine the total microbial numbers (TMNs) where consumers find that the quality of whole fresh chilled pasteurised milk (WFCPM) and skim milk (Trim) stored at 4.5 ± 0.5 °C is no longer acceptable. Food spoilage progression was supported by measurements of VOCs and the terms consumers used to describe the ageing fresh chilled pasteurised milk (FCPM). RjTs for TMN of 7.43 and 7.34 log10 CFU.mL−1 for WFCPM and Trim, respectively were derived using Hill's equation from a series of paired preference tests comparing fresh and aged milks (3–26 days) assessed by consumers (WFCPM, n = 55; Trim, n = 52). A poor relationship between storage time and TMN was found, owing mainly to batch-to-batch and within-batch variation in the milk's post-pasteurization contamination (PPC) levels. At the RjT, there was a significant change in the signal intensities for a number of spoilage-related VOCs that occurred in the FCPM headspace (p ≤ 0.05), which were measured using proton transfer reaction–mass spectrometry (PTR-MS), including m/z 33, 45, 47, 61, 63, 69, 71, 87, and 89, tentatively identified as methanol; acetaldehyde; ethanol; acetate (acetic acid and acetate esters); dimethyl sulphide (DMS); isoprene, furan, and aldehydes; 2-butanone; and pentanal and butyrates (butyric acid and butyrate esters), respectively. Consumers described the milks at TMN greater than the RjTs using terms like off, expired, sour, spoilt or rancid. This multidisciplinary study has provided data on the importance of PPC and subsequent increases in TMN on VOCs associated with FCPM and consumer's preferences and highlighted the value of measuring a range of variables when investigating consumer's perception of food quality and shelf-life. [ABSTRACT FROM AUTHOR]

The consumer rejection threshold (RjT) method was applied to determine the total microbial numbers (TMNs) where consumers find that the quality of whole fresh chilled pasteurised milk (WFCPM) and skim milk (Trim) stored at 4.5 ± 0.5 °C is no longer acceptable. Food spoilage progression was supported by measurements of VOCs and the terms consumers used to describe the ageing fresh chilled pasteurised milk (FCPM). RjTs for TMN of 7.43 and 7.34 log10 CFU.mL−1 for WFCPM and Trim, respectively were derived using Hill’s equation from a series of paired preference tests comparing fresh and aged milks (3–26 days) assessed by consumers (WFCPM, n = 55; Trim, n = 52). A poor relationship between storage time and TMN was found, owing mainly to batch-to-batch and within-batch variation in the milk’s post-pasteurization contamination (PPC) levels. At the RjT, there was a significant change in the signal intensities for a number of spoilage-related VOCs that occurred in the FCPM headspace (p ≤ 0.05), which were measured using proton transfer reaction–mass spectrometry (PTR-MS), including m/z 33, 45, 47, 61, 63, 69, 71, 87, and 89, tentatively identified as methanol; acetaldehyde; ethanol; acetate (acetic acid and acetate esters); dimethyl sulphide (DMS); isoprene, furan, and aldehydes; 2-butanone; and pentanal and butyrates (butyric acid and butyrate esters), respectively. Consumers described the milks at TMN greater than the RjTs using terms like off, expired, sour, spoilt or rancid. This multidisciplinary study has provided data on the importance of PPC and subsequent increases in TMN on VOCs associated with FCPM and consumer’s preferences and highlighted the value of measuring a range of variables when investigating consumer’s perception of food quality and shelf-life.

Highlights • Methyl anthranilate (MA) and 2-aminoacetophenone (2AAP) were evaluated in wine. • Rejection thresholds are determined as an estimate for wine acceptability. • Threshold values were variable based on wine knowledge of the evaluator. • Detectable levels of MA and 2AAP in vinifera wine did not cause complete rejection. Abstract Methyl anthranilate (MA) and 2-aminoacetophenone (2AAP) are commonly associated with the flavor of wines made from V. labruscana grapes. It is widely assumed that wine experts and consumers find these flavors to be objectionable, at least in wines vinified from V. vinifera grapes. Here, a two-alternative forced-choice task was used to compare preference for unoaked Chardonnay against the same Chardonnay spiked with MA or 2AAP in ascending concentration series. Participants were either wine experts from California, or non-expert wine consumers from California or Pennsylvania. Wines were evaluated in the mouth and participants were instructed to indicate which sample within a pair they preferred. Rejection threshold estimates were determined by regressing 2AFC responses against concentration. Consistent with the expectation that experts view V. labrusca associated odors as a fault, wines with high concentrations of methyl anthranilate were largely rejected by wine experts in California. However, non-expert consumers in California were more tolerant than the wine experts in California, and non-expert consumers in Pennsylvania showed little to no influence of added methyl anthranilate on their preferences. Contrary to expectations however, 2-aminoacetophenone failed to elicit rejection in California wine experts or consumers within the range tested. Our results suggest that while V. vinifera wines may occasionally contain amounts of methyl anthranilate and 2-aminoacetophenone that are detectable in chemical analysis, the presence of these odorants at levels naturally found in V. vinifera wines is insufficient to elicit rejection from wine experts or consumers, regardless of their regional wine culture. [ABSTRACT FROM AUTHOR]

Highlights • Bioactive casein hydrolysate (NaCaHs) have potential for use in functional foods. • Peptide molecular weight influence the bitterness and bioactivity in NaCaHs. • Rejection threshold models applied to NaCaHs with different bitter profiles. • Consumer rejection thresholds for the NaCaHs is influenced by the food matrix. Abstract This study aimed to identify the amount of crude casein-hydrolysate (HMW) and a low molecular weight sub-fraction (LMW) thereof that could be incorporated into strawberry- and vanilla-flavoured beverages before the bitterness/taste became objectionable to panellists. The beverages were spiked with increasing amounts of hydrolysate and a 2-alternative forced choice (2-AFC) design was employed to determine rejection thresholds (RjT). Results showed a higher amount of HMW, than LMW, could be incorporated into the beverages before the taste became objectionable and the type of flavouring did not have a significant effect on RjT. Following the 2-AFC, panellists rated the bitterness of the hydrolysates (in water) on a general Labelled Magnitude Scale (gLMS). Results showed no significant differences between the bitterness perception of the HMW and LMW. However, there was considerable variation in the panellists' perception of bitterness, suggesting possible evidence for segmentation. Using this rationale, each panel was segmented into two groups: those who rated the bitterness of the hydrolysate samples as ≤20 on the gLMS and, those who rated the bitterness as ≥75 on the gLMS, and RjT were examined within them. Although a trend was seen for those most sensitive to bitterness in water, to have a lower acceptance for the level in the beverages, the RjT of the segmented groups were not significantly different from each other. Evaluation of hydrolysates in water does therefore not appear to be suitable for predicting consumer acceptance of hydrolysates in food matrices; highlighting the importance of testing food ingredients in the final food product. [ABSTRACT FROM AUTHOR]

Recently, sensory threshold concepts have been expanded to include affective perceptions of foods and beverages, especially measures of product rejection; however, each threshold interpretation depends largely on the methodology employed. By substituting cricket powder for whole-wheat flour in snack crackers (0%, 5%, 10%, 15%, and 20%), we proposed modifications to two existing threshold methodologies: a modified consumer rejection threshold (M-CRT) using a 2-alternative choice (2-AC) preference test with “no preference” option; and a modified hedonic rejection threshold (M-HRT) based on less-than-neutral hedonic scores according to a one-sample t-test. We also proposed two new concepts: a rejection tolerance threshold (RTT) and an associated rejection range (RR), based on a binomial acceptability question and a probit regression model. These new methods provide more realistic interpretations of rejection-type thresholds based on user-defined allowable rejection levels, or “rejection tolerance” (for RTT), and a model-derived stimulus range (RR) to capture the rejection level of interest while providing flexibility for product formulation. All thresholds were investigated separately for color, flavor, texture and overall perception, elucidating differential sensorial effects of our novel ingredient on the food matrix. We suggest that conducting all demonstrated techniques in a single testing session gives a more expansive view of rejection thresholds while requiring minimal additional resources.

An OCR process is often followed by the application of a language model to find the best transformation of an OCR hypothesis into a string compatible with the constraints of the document, field or item under consideration. The cost of this transformation can be taken as a confidence value and compared to a threshold to decide if a string is accepted as correct or rejected in order to satisfy the need for bounding the error rate of the system. Widespread tools like ROC, precision-recall, or error-reject curves, are commonly used along with fixed thresholding in order to achieve that goal. However, those methodologies fail when a test sample has a confidence distribution that differs from the one of the sample used to train the system, which is a very frequent case in post-processed OCR strings (e.g., string batches showing particularly careful handwriting styles in contrast to free styles). In this paper, we propose an adaptive method for the automatic estimation of the rejection threshold that overcomes this drawback, allowing the operator to define an expected error rate within the set of accepted (non-rejected) strings of a complete batch of documents (as opposed to trying to establish or control the probability of error of a single string ), regardless of its confidence distribution. The operator (expert) is assumed to know the error rate that can be acceptable to the user of the resulting data. The proposed system transforms that knowledge into a suitable rejection threshold. The approach is based on the estimation of an expected error vs. transformation cost distribution. First, a model predicting the probability of a cost to arise from an erroneously transcribed string is computed from a sample of supervised OCR hypotheses. Then, given a test sample, a cumulative error vs. cost curve is computed and used to automatically set the appropriate threshold that meets the user-defined error rate on the overall sample. The results of experiments on batches coming from different writing styles show very accurate error rate estimations where fixed thresholding clearly fails. An original procedure to generate distorted strings from a given language is also proposed and tested, which allows the use of the presented method in tasks where no real supervised OCR hypotheses are available to train the system. [ABSTRACT FROM AUTHOR]

Recently, sensory threshold concepts have been expanded to include affective perceptions of foods and beverages, especially measures of product rejection; however, each threshold interpretation depends largely on the methodology employed. By substituting cricket powder for whole-wheat flour in snack crackers (0%, 5%, 10%, 15%, and 20%), we proposed modifications to two existing threshold methodologies: a modified consumer rejection threshold (M-CRT) using a 2-alternative choice (2-AC) preference test with "no preference" option; and a modified hedonic rejection threshold (M-HRT) based on less-than-neutral hedonic scores according to a one-sample t-test. We also proposed two new concepts: a rejection tolerance threshold (RTT) and an associated rejection range (RR), based on a binomial acceptability question and a probit regression model. These new methods provide more realistic interpretations of rejection-type thresholds based on user-defined allowable rejection levels, or "rejection tolerance" (for RTT), and a model-derived stimulus range (RR) to capture the rejection level of interest while providing flexibility for product formulation. All thresholds were investigated separately for color, flavor, texture and overall perception, elucidating differential sensorial effects of our novel ingredient on the food matrix. We suggest that conducting all demonstrated techniques in a single testing session gives a more expansive view of rejection thresholds while requiring minimal additional resources. [ABSTRACT FROM AUTHOR]