Introduction
After fabrication, deoxymyoglobin (purple) is exposed to oxygen, becoming oxymyoglobin (bright red), and eventually oxidizes to form metmyoglobin (brown), which is often perceived as unappealing to consumers (Mancini and Hunt, 2005). The color of raw meat products is one of the most important visual factors that influence a consumer’s decision to purchase (Mancini and Hunt, 2005). Most American consumers are accustomed to buying beef that is a bright, cherry-red color (Suman and Joseph, 2013). Discoloration of beef results in a major economic loss of $3.73 billion of product loss per year (Ramanathan et al., 2022). Antioxidants can slow this process by scavenging free radicals and chelating metal ions, which delay the conversion of deoxymyoglobin and oxymyoglobin to metmyoglobin (Lee et al., 2020). Antioxidants can also delay lipid oxidation through mechanisms such as breaking radical-chain reactions (Frankel, 1996). Lipid oxidation refers to the degradation of fatty acids into products like aldehydes, ketones, and alcohols, which cause a rancid flavor that can be detected during consumption of the product (Domínguez et al., 2019). If a consumer encounters these flavors, it may negatively influence their decision to repurchase. Commonly used antioxidants are butylated hydroxyanisole, butylated hydroxytoluene, tert-butylhydroquinone, and propyl gallate; however, alternatives to chemically synthesized options have gained interest in the consuming public (Naveena et al., 2008; Oswell et al., 2018).
While meat color is a major factor to consider for meat products, it does not impact the wholesomeness or palatability of the product. The microbial load on a product does and is the main cause of meat spoilage in up to 20% of retail and consumer environments (Saucier, 2016). To further improve product quality, the meat industry often utilizes antimicrobials such as lactic acid or peracetic acid to reduce microbial counts (Mani-López et al., 2012). Meat color can be impacted by microbial load, which also affect sensory characteristics such as taste and smell (Dave and Ghaly, 2011). Meat provides a highly suitable environment for microbial growth due to its high-water activity, high-nutrient availability, and suitable pH (Zhou et al., 2010).
The previously mentioned ingredients have been developed and evaluated to work in meat products and aid in controlling oxidation and microbial growth. However, there is a currently a demand from consumers for ingredients they recognize and consider as “healthy” (Asioli et al., 2017). Ingredients from natural sources can meet these expectations while also preserving food products (Maddaloni et al., 2025). Hops (Humulus lupulus) are being researched to aid in filling this consumer demand. Hops contain a unique variety of constituents, most notably bitter acids and phenolics, which contribute to the flavor, antioxidant capacity, and antimicrobial activity characteristic of hops. Bitter acids are primarily responsible for antimicrobial activity, whereas phenolics are primarily responsible for antioxidant activity (Arruda et al., 2021). The study of the use of hops as an ingredient in food products is timely as the demand of hops for brewing decreases, due to an increasing number of brewery closures over the last 4 y (Kunce, 2025). This decrease in demand has led to lower hop production and a fluctuation in hop prices. The objective of this study was to assess the color stability and consumer acceptability of beef patties when using hop extracts as a natural ingredient.
Methods and Materials
The consumer sensory evaluation protocol was reviewed and approved by the University of Idaho Institutional Review Board (029435).
Product preparation
US Department of Agriculture (USDA) Choice beef shoulder clods (IMPS 114C) were obtained from a USDA inspected commercial meat processing facility and transported to the Vandal Brand Meats facility under refrigeration at 1.1°C and were wet aged for 13 d postpacking in vacuum bags. The shoulder clods were coarse ground through a 10-mm plate and subsequently fine ground through a 3-mm plate (Thompson Meat Machinery Model 3000 meat mixer-grinder, Ixonia, Wisconsin). The lean-to-fat ratio was recorded at 83 to 17, utilizing a Univex FA73 Fat Analyzer (Salem, New Hampshire). The ground beef was measured into 5 treatments of 4.54 kg each: control (no hop extract), 3 levels of a dry-hop extract (5, 10, and 20 ppm) and 1 level of an aqueous-hop extract (111 ppm). The level of 111 ppm of the aqueous-hop extract was chosen because it has similar levels of hop bitter acids as the 20-ppm dry-hop extract according to manufacturer product specifications (BetaTec hop products, Yakima, Washington). Batches consisted of 4.54 kg of ground beef with a standardized seasoning mixture of 1% salt, 15% water, 0.2% onion granules, and the designated hop-extract treatment. Ingredients were added as a percentage of the meat block. Each batch was mixed for 2.5 min at 29 revolutions per minute in a DMX 50 mixer (Daniels Foods Equipment DMX 50 mixer, Parkers Prairie, Minnesota) and then formed using a Patty-O-Matic 330A (Patty-O-Matic Inc. Model 330A, Farmingdale, New Jersey) patty former into 16 mm-thick patties, weighing 150 g each. Two patties from each batch were analyzed for retail color, aerobic microbial growth, and lipid oxidation. Three patties were used for sensory analysis. Patties designated for retail display and sensory analysis were placed in 10S white foam trays (Walton’s SKU: 4610028), while patties for all other analyses were placed in 4S white foam trays (Walton’s SKU: 4610025). All trays were then overwrapped with an oxygen permeable polyvinyl chloride film (oxygen transmission rate: 1450 cc/645 cm2/24 h; water vapor transmission rate: 17.0 g/645 cm2/24 h; Koch Industries, Inc., #7500-3815; Wichita, Kansas).
Retail display color
Patties were allowed to bloom for at least 60 min at 3°C, then 2 objective color measurements per patty were taken using a Hunter MiniScan EZ 4500L Spectrophotometer (Restin, Virginia) over the polyvinyl chloride film. This represented day 0 of retail display, and subsequent color measurements were taken every 24 h on days 1, 2, 3, and 4. The Hunter MiniScan was equipped with a 25-mm diameter measuring area and a 10° standard observer. The instrument was set to illuminant A10, and Commission Internationale de l’Èclairage L*, a*, and b* values were recorded. Calibration of the machine was carried out each day by measuring against black and white calibration tiles prior to data collection. The total color change (ΔE) was then calculated for each retail display day relative to day 0 of retail display. Day 0 observations were excluded from statistical analysis, as ΔE equals zero by definition and shows no variation in comparisons.
Total color change was calculated using the following equation:
where ΔL*, Δa*, and Δb* represent the differences in L*, a*, and b* values between each day and day 0.Ground-beef color and discoloration were measured daily by 3 trained evaluators following American Meat Science Association (AMSA) guidelines for meat color measurement (King et al., 2023). Evaluators, between 20 and 28 y old, were screened for color blindness using the Farnsworth-Munsell 100-Hue test and accepted if they returned a score of 50 or less. Patties were exhibited in a retail display room on a multideck display case at 3°C for 4 d. The display room was equipped with natural white Hg 4000-W lights (Fisherbrand Traceable Dual-Range Light Meter, Fisher Scientific, Waltham, Massachusetts), and the average light intensity was 849 lux. To avoid potential effects due to display location, patties were systematically rotated daily.
Retail fluid loss
Patties from each batch were weighed on day 0 to determine an initial weight and then packaged for retail display as stated above. Patties were then reweighed on day 4 of retail display to determine their final weight.
Percent retail fluid loss was calculated using the following equation:
Microbial growth
To monitor bacterial growth at the surface of samples, aerobic microbial population of raw (day 0) and raw stored (days 2 and 4) fresh beef patties were evaluated by surface sampling patties using Neogen® Quick Swab (SKU No. 700002200, Lansing, Michigan). The microbial culture from the Swab-Sampler was then plated on Neogen® Petrifilm® aerobic count plates (SKU No. 700002116, Lansing, Michigan). Three dilutions were made at 10−1, 10−2, and 10−3. After dilutions were plated on the petrifilms, they were placed in an incubator under aerobic conditions at 30°C ± 1°C. The viable cultures were enumerated 48 h ± 3 h after sampling (NF validation certified method in compliance with ISO 16140-26). Data were transformed using log10, and data that showed no detectable colonies were reported as 0 with no log10 transformation.
Lipid oxidation
Thiobarbituric acid reactive substances (TBARS) were analyzed on day 0, 2, and 4 of the retail display period utilizing the rapid, wet protocol provided in Appendix D, Section Q of the AMSA guidelines for meat color measurement (King et al., 2023) but modified to use 0.25 g rather than 0.5 g. Samples were taken from the edge of the patty and weighed to 0.25 g ± 0.005 g. Absorbance was measured at 532 nm against a reagent blank, utilizing a microplate reader (BioTek Synergy 2, BioTek Instruments, Winooski, Vermont). TBARS values were expressed as mg malondialdehyde (MDA)/kg meat and were calculated using the extinction coefficient of the TBA pink chromogen (King et al., 2023). Values were calculated using the following equation: TBARS (mg MDA/kg meat) = A532 × 2.77.
Sensory analysis
A consumer panel was conducted at the University of Idaho Margaret Ritchie School of Family and Consumer Sciences in the Niccolls Home Economics building test kitchen (Moscow, Idaho) on day 1 of retail display. Eighty-four consumer panelists were recruited through an open invitation sent to the University of Idaho community. Panelists age ranged from 18 to 56 y old. On average, panelists were 24 y old and consumed a meal containing beef 2 to 4 times a week. Patties were cooked on a Cuisinart™ Griddler® Deluxe (model GR-150P1) to a target internal temperature of 71°C. The internal temperature of the patties was monitored using an Atkins EconoTemp thermometer (model 32311-K). After cooking, each patty was cut into 8 equal pieces following the protocol provided in chapter VI, section A of the Research Guidelines for Cookery, Sensory Evaluation, and Instrumental Measurements of Meat (AMSA, 2016). Of the 8 pieces cut from each patty, 4 to 5 pieces were plated depending on the batch and the replicate in that batch. Samples were equally distributed among the 84 consumer panelists. After plating, samples were then stored in an Alto-Shaam cook and hold oven (model 1200-TH/III) at 49°C. Panelists were served samples in covered cups, labeled with a 3-digit randomized binding code. Consumer panelists were given paper ballots to rate patties for overall acceptability, tenderness, juiciness, and flavor using a 10-point hedonic scale, where 10 equaled like extremely, like tenderness extremely, like juiciness extremely, and like flavor extremely, respectively; and 1 equaled dislike extremely, dislike tenderness extremely, dislike juiciness extremely, and dislike flavor extremely, respectively. Additionally, for each sample, consumers were asked if they could detect an off flavor, if they would be willing to purchase the product, and what trait (flavor, juiciness, or tenderness) they liked the most and the least by circling the corresponding answer on the sheet.
Statistical analysis
Data were analyzed using R Statistical Software (v 4.4.1; R Core Team 2025). Packages emmeans, nlme, and lmerTest were used for linear modeling, post hoc comparisons, and estimation for the marginal means from the linear. Batches served as experimental units (n = 6). Retail color, microbial growth, and lipid oxidation were analyzed using a mixed linear model that included day as a repeated measure and batch and replicate as random effects. Retail fluid loss was analyzed using a mixed linear model with batch and replicate as random effects. Consumer sensory was analyzed using a mixed linear model with panelist, batch, and replicate as random effects. Treatment was used as a fixed effect in all parameters. Differences in marginal means were compared using emmeans (Lenth, 2023). A Tukey adjustment was used in pairwise comparisons. Statistical significance was considered at a P value less than or equal to .05, and a trend in the data was at P value of less than or equal to .10.
Results and Discussion
Retail objective color
There was a hop treatment by day of retail display interaction observed in the a* readings (P = .004; Table 1). On day 0, the patties treated with 20 ppm dry- and 111 ppm aqueous-hop extracts had reduced redness when compared to the control patties (P = .015 and P = .005). This is unexpected, as those treatments had the highest concentration of hop extracts that contain known antioxidant polyphenols, such as xanthohumol. These antioxidants generally aid in reducing oxidation through scavenging free radicals, chelation, and its natural reducing properties. It was expected that hop-treated patties would have improved redness (Długosz et al., 2025). In another study on DNA oxidative damage of Saccharomyces cerevisiae (Carvalho et al., 2016), it was found that when xanthohumol is used at higher concentrations it can act as a prooxidant, which is a possible explanation for the initial decrease in a* values in the hop extracts with the high concentration of hop acids. By day 2 of retail display, all treatments became similar in a* mean values. However, all treatments ended with an a* mean value greater than 14.5 (Table 1), which is considered acceptable to consumers based on previous research of fresh beef color (Holman et al., 2017).
Effect of retail display day by treatment interaction on mean a* values and subjective color scores throughout simulated retail display
| Trait | Day | Control | 5 ppm | 10 ppm | 20 ppm | 111 ppm | SEM | P Value |
|---|---|---|---|---|---|---|---|---|
| a*1 | 0 | 31.1a | 29.5ab | 30.3ab | 28.4bc | 28.1bcd | 0.420 | .004 |
| 1 | 26.0cdef | 25.5ef | 25.6ef | 24.5efg | 25.0ef | |||
| 2 | 26.4cde | 26.4cde | 26.5cde | 25.9def | 26.2cde | |||
| 3 | 24.6ef | 24.6ef | 24.3efgh | 23.6fghi | 24.8ef | |||
| 4 | 22.1ghij | 21.9hij | 21.6ij | 21.0j | 22.1ghij | |||
| Subjective color2 | 0 | 1.36h | 1.28h | 1.36h | 1.36h | 1.47h | 0.078 | .025 |
| 1 | 2.06g | 2.07g | 2.03g | 2.25g | 2.21g | |||
| 2 | 3.13e | 2.94ef | 2.85f | 2.96ef | 3.01ef | |||
| 3 | 4.58c | 4.44cd | 4.36cd | 4.53cd | 4.31d | |||
| 4 | 5.49ab | 5.56a | 5.47ab | 5.53ab | 5.31b |
SEM, standard error of means.
a* = redness, −50 = green, and 50 = red. Measured by HunterLab MiniScan EZ 4500L by day of retail display.
Subjective color: 1 = very bright red, 2 = bright red, 3 = dull red, 4 = slightly dark red, 5 = moderately dark red, 6 = dark red, 7 = dark reddish tan, and 8 = tan to brown. Measured by trained panelist for fresh beef patties by day of retail display.
Means without a common superscript differ (P < .05).
There was no interaction observed between hop treatment by day of retail display for objective color in L* (P = .934) or b* (P = .137) readings. Treatments differed for L* (P < .001). Although mean values of the 5 ppm and 20 ppm treatments were not different from each other, they were both lighter than the control (P = .037 and P = .008, respectively; Figure 1). There was a difference between days in mean values of both L* and b* (P < .001 and P < .001, respectively; Table 2). L* and b* mean values both decreased and became darker and bluer over the retail display period. This differs from previous research done on ground lamb using a powdered hop product, which found that while lamb L* had an initial decrease during the early storage period, it ended with a higher L* value by the end of storage (Villalobos-Delgado et al., 2015). This difference may be due to the longer retail display period (7 d compared to the 5 d used in this study), species difference, or storing the lamb in darkness rather than a lighted retail cooler.
The effect of treatment on L* values of beef patties. The effect of treatment on L* values of beef patties. Objective L* color measured by HunterLab MiniScan EZ 4500L by day of retail display for fresh beef patties. Values were taken from the mean of each treatment across all days. Batches (N = 30) were assigned to a treatment, which was included as a part per million of the meat block. Treatments included: control (no hop extract), 5 ppm dry-hop extract, 10 ppm dry-hop extract, 20 ppm dry-hop extract, and 111 ppm aqueous-hop extract. Values are shown as least-squares means ± standard error (0.166). a–cMeans without a common superscript differ (P < .05).
The effect of treatment on L* and b* values throughout retail display
| Trait | Day of Retail Display | SEM | P Value | ||||
|---|---|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | |||
| L*1 | 51.4b | 52.4a | 48.9c | 48.5c | 48.8c | 0.164 | <.001 |
| b*2 | 23.1a | 19.6d | 22.4ab | 21.8b | 20.4c | 0.212 | <.001 |
SEM, standard error of means.
L* = lightness, 0 = black, and 100 = white. Measured by HunterLab MiniScan EZ 4500L by day of retail display.
b* = yellowness, −50 = blue, and 50 = yellow. Measured by HunterLab MiniScan EZ 4500L by day of retail display.
Means without a common superscript differ (P < .05).
There was no observed interaction between hop treatment by day of retail display (P = .429). There was also no treatment effect observed for total color change values (P = .431). A day effect was seen in total color change values (P < .001) in which each retail day’s value was over the theoretical threshold of 1.0, which indicates the human eye can detect a difference in color when compared to day 0 of retail display (King et al., 2023). It is worth noting that across all days and all treatments, the mean ΔE values were greater than 4.74. This indicated that a difference would be perceptible to the human eye in the beef patties in comparison to the same patties on day 0 of retail display.
While compared to the results of retail subjective color, total color change differs as there was no interaction between treatment by day of retail display (P = .429) when retail subjective color did experience an interaction (P = .025). Another difference is observed when comparing the day effects of each protocol. When looking at significance of day of retail display, total color change shows no difference when comparing day 1 of retail display to day 3 (P = .978), whereas retail subjective color shows differences in comparison to all days (P < .001).
The differences observed between total color change and the retail subjective color can be due to the retail subjective color protocol, mainly examining the redness of the beef patties as that is the main driver of consumer acceptance (Suman and Joseph, 2013). While total color change represents the magnitude of change across all color parameters, a change in L* or in b* may influence the value without redness being affected. Additionally, total color change is an objective instrumental measurement, whereas retail subjective color may be influenced by lighting or other environmental appearance factors (King et al., 2023).
Retail subjective color
There was a hop treatment by day of retail display interaction observed for subjective color (P = .025; Table 1). On day 2 of retail display, the patties treated with the 10 ppm hop extract differed from the control patties (P = .018), and the 10 ppm treated patties were perceived as having a brighter red color compared to the control patties being duller red. By day 3, the 10 ppm treated patties showed comparable color to the control patties and remained similar through the end of the study. On day 3 of retail display, the 111 ppm hop-extract treated patties differed from the control (P = .018). The 111 ppm patties were perceived by the panelists as having a slightly darker red color compared to the control having a more moderate dark red color. The 111 ppm hop-extract patties were similar to the control patties on the last day of retail display. On day 4, the 111 ppm and 5 ppm treated patties differed (P = .032). The panelists perceived the 5 ppm treated patties as being darker when compared to the 111 ppm treated patties.
Retail fluid loss
There were no observed differences between hop treatments regarding mean retail fluid loss (P = .484), where a pooled average retail fluid loss of 2.214% was observed among all treatments. It has been observed that 2% or less of fresh meat retail fluid loss is considered normal, while a loss of more than 4% would be considered excessive (Johnson, 1974). The average fluid loss found in the current study was slightly above the threshold of what would be considered normal fluid loss. However, it is notably below what would be considered excessive. This implies that at the concentrations used in this study, hop extracts do not demonstrate water binding abilities.
Microbial growth
A hop treatment by day of retail interaction was observed for bacterial aerobic plate count (P = .022; Figure 2). The beef patties treated with 20 ppm dry-hop extract on day 0 started with the lowest bacterial aerobic plate count (0.315 log CFU). On day 4, the 20 ppm dry-hop extract ended with the lowest bacterial aerobic plate count (1.603 log CFU) but similar to 10 ppm and 111 ppm. The 20 ppm dry-hop extract treatment result is expected, as it has been previously observed, to be an antimicrobial for spoilage microorganisms in fresh chicken (Nieto et al., 2020). The patties treated with 111 ppm aqueous-hop extract started with the highest bacterial aerobic plate count (1.635 log CFU), yet by day 2, they had a similar mean bacterial aerobic plate count compared to the other treatments, which continued through day 4. The result of the aqueous-hop extract treatment is interesting and could be due to how the product is manufactured. Further research utilizing only the fatty acids that the hop extract is homogenized in as a negative control is needed to test that hypothesis. However, the treatments and control were not considered to be microbially spoiled, as they did not reach the limit of 7 to 8 log CFU that has been reported by previous research to emit off-odors and slime formation (Nychas et al., 2008). If this experiment had a longer display period, microbial spoilage may have been observed. It is worth noting that the bioactive components of hops are much more effective against Gram-positive organisms when compared to Gram-negative organisms (Arruda et al., 2021). Further study is needed to test hop-extract effectiveness against Gram-negative pathogens such as Escherichia coli 0157:H7.
The interaction of treatment by day of retail display on aerobic barcteria counts. Aerobic bacteria count measured by Neogen Aerobic Count petrifilms treatments by day of retail display for fresh beef patties. Batches (N = 30) were assigned to a treatment, which was included as a part per million of the meat block. Treatments included: control (no hop extract), 5 ppm dry-hop extract, 10 ppm dry-hop extract, 20 ppm dry-hop extract, and 111 ppm aqueous-hop extract. Aerobic count was measured on day 0, day 2, and day 4 of retail display. Values are shown as least-squares means ± standard error (varies by treatment by day of retail display). a–gMeans without a common superscript differ (P < .05).
Lipid oxidation
Lipid oxidation observations found a hop treatment by day interaction (P < .001; Figure 3). The patties treated with 111 ppm aqueous-hop extract on day 0 started with the least amount of lipid oxidation (0.345 mg MDA/kg), potentially indicating a delay in the initiation phase of lipid oxidation. On day 2 of retail display, the 10 ppm dry-hop extract treatment (0.927 mg MDA/kg) had more lipid oxidation than the 111 ppm aqueous-hop extract treatment (0.797 mg MDA/kg; P = .035). On day 4, patties treated with 10 ppm dry-hop extract and 111 ppm aqueous-hop extract had less lipid oxidation observed (1.25 and 1.245 mg MDA/kg, respectively) when compared to the control. By the final day of retail display, all treatments were observed to have mean MDA values above the 1-mg MDA/kg threshold, which indicates consumers would likely taste oxidative rancidity by the end of the retail display period (Oliveira et al., 2025).
The interaction of treatment by day of retail display on lipid oxidation of beef patties. Oxidation measured by TBARS for antioxidant treatments by day of retail display for fresh beef patties. Batches (N = 30) were assigned to a treatment, which was included as a part per million of the meat block. Treatments included: control (no hop extract), 5 ppm dry-hop extract, 10 ppm dry-hop extract, 20 ppm dry-hop extract, and 111 ppm aqueous-hop extract. TBARS were measured on day 0, day 2, and day 4 of retail display. Values are shown as least-squares means ± standard error (0.023). a–fMeans without a common superscript differ (P < .05). MDA, malondialdehyde; TBARS, thiobarbituric acid reactive substances.
Sensory analysis
In the consumer sensory panel, consumers were asked if they could detect an off flavor and if they would be willing to purchase the product. There were no differences observed between treatments for willingness to purchase or off flavors (P = .356 and P = .695, respectively; Table 3). Additionally, there were no differences for overall acceptability, tenderness, juiciness, or flavor observed among treatment means (P = .960, P = .746, P = .725, and P = .929, respectively; Table 3). The concentrations of hop extracts used in treated patties (5, 10, and 20 ppm dry-hop extract treatments and 111 ppm aqueous-hop extract treatment) were not distinguishable to the consumer panelists in the sensory evaluation. The observation of no differences in palatability among hop treatments was a promising result since hops are known to have a bitter flavor due to the prenylated polyketides, α-acids, and β-acids (Dresel et al., 2016).
Mean values of consumer sensory panel on the acceptability of ground-beef patties using hop extracts ± the standard error of the mean
| Trait | Control | 5 ppm | 10 ppm | 20 ppm | 111 ppm | P Value |
|---|---|---|---|---|---|---|
| Off flavor detection probability | 14.3% ± 4.18% | 10.0% ± 3.43% | 14.8% ± 4.25% | 12.4% ± 3.91% | 17.4% ± 4.73% | .695 |
| Willingness to buy probability | 83.3% ± 4.64% | 85.6% ± 4.28% | 80.9% ± 5.04% | 76.9% ± 5.50% | 88.1% ± 3.91 | .356 |
| Overall acceptability1 | 7.24 ± 0.225 | 7.22 ± 0.226 | 7.18 ± 0.225 | 7.28 ± 0.226 | 7.37 ± 0.229 | .960 |
| Tenderness2 | 7.23 ± 0.237 | 6.98 ± 0.237 | 7.06 ± 0.237 | 7.14 ± 0.237 | 7.33 ± 0.240 | .746 |
| Juiciness3 | 6.41 ± 0.239 | 6.79 ± 0.239 | 6.69 ± 0.239 | 6.74 ± 0.239 | 6.67 ± 0.243 | .725 |
| Flavor4 | 7.13 ± 0.254 | 7.11 ± 0.254 | 7.01 ± 0.254 | 6.93 ± 0.254 | 7.19 ± 0.258 | .929 |
Overall acceptability: 1 = not acceptable at all, and 10 = extremely acceptable.
Tenderness: 1 = not tender at all, and 10 = extremely tender.
Juiciness: 1 = not juicy at all, and 10 = extremely juicy.
Flavor: 1 = very bad flavor, and 10 = very good flavor.
Conclusion
In beef patties containing minimal added ingredients, hop extracts have the potential to reduce food waste by improving shelf-life parameters such as reducing aerobic microbial load, delaying lipid oxidation, and improving subjective color while maintaining a clean label. The use of hop extracts as a food ingredient can aid the hop industry during a time in which hops use is decreasing. Future research avenues include increasing the concentrations of the hop extracts to determine the maximum amount that can be added without negatively impacting consumer acceptability. Additionally, the mixing of the dry- and aqueous-hop extracts may result in reductions in both microbial growth and lipid oxidation, thereby possibly further extending shelf-life. The effect of freezing and thawing on beef patties containing hop extracts should also be explored since extended frozen storage of beef patties can result in greater oxidation and warmed over flavors. Finally, using a known antioxidant, like rosemary extract, along with a hop extract should be studied since the rosemary extract may positively impact the color of the beef patties, while the hop extract would decrease microbial load.
Conflict of Interest
Hop extracts and funding were provided by BetaTec hop products. The authors declare there are no other conflicts of interest.
Acknowledgments
This research was funded by BetaTec hop products. The authors gratefully acknowledge financial support from BetaTec and assistance in procuring product. The authors are also appreciative of the personnel at the University of Idaho Vandal Brand Meats Laboratory that made this research possible.
Author Contribution
C.F.: data curation, formal analysis, investigation, methodology, resources, visualization, writing—original draft, and writing—review and editing; Y.G.: formal analysis, investigation, and writing—review and editing; C.S.: investigation and writing—review and editing; J.V.B.: investigation and writing—review and editing; P.E.: investigation; T.G.: investigation. J.N.: investigation and resources; M.C.: conceptualization, funding acquisition, methodology, project administration, supervision, validation, and writing—review and editing; and P.B.: conceptualization, supervision, validation, and writing—review and editing.
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