Three types of sausage patties (two plant- and one animal-based) were purchased and refrigerated at either 1 °C, 4 °C or 7 °C. Temperature fluctuations and relative humidity data were monitored during refrigerated storage using sensors. Sausage and sausage analogue quality was evaluated by measuring total aerobic bacteria, per cent drip loss, colour, water activity, pH, GC-headspace volatiles, proximate composition (moisture, fat, protein content), water holding capacity, sensory analysis, TPA, and cooking yield. Refrigeration temperature affected the shelf life and quality of the patties. Patties subjected to a storage temperature of 7 °C had lower quality and shortened shelf life as evidenced by higher microbial counts and less desirable color and texture. Conversely, a refrigeration temperature of 1 °C was associated with relatively higher quality patties with lower microbial counts and higher cooking yield. Superior textural properties were recorded for patties that were refrigerated at 4 °C using TPA. Morningstar patties had the highest quality, reflected by lower microbial counts, lower moisture loss, and higher sensory scores.


Consumers are seeking plant-based alternatives to meat due to perceived environmental and health concerns [1]. Ideal meat analogues have similar quality characteristics of animal-based products, that include sensory attributes of texture and flavor and nutritional qualities such as fat and protein content.

Research on storage and quality of plant-based meat analogues is lacking; however, studies on traditional sausage patties suggest they can remain refrigerated for approximately 7 days in 4.4 °C with minimal effect on quality [2]. Optimal storage is essential to generate the best possible food quality and high sensory acceptability [3].

Storage temperature affects the quality of meat and meat analogues. Moreover, proper management of temperature will decrease the rate of food spoilage, thereby extending shelf life [4] and reducing food waste. Joo et al. [5] divided meat quality into three components, including reliance, appearance, and eating quality traits. Reliance quality traits refer to the safety of meat and can be determined using chemical, microbiological, and physical tests, while consumers typically rely on appearance quality traits when purchasing items since a visual assessment is often the only way to assess quality at the point of purchase [5], [6]. Consumers decide on whether or not to purchase an item again based on their eating quality traits [5], [6]. Appearance properties, such as colour, result from visual inspection to determine the perceived freshness of meat, whereas eating quality refers to how the product is perceived in terms of flavour and texture [4], [6]. Most studies are conducted with these characteristics in mind in order to thoroughly investigate quality attributes and changes.

The objective of this study was to determine the effect of storage temperature (1 °C, 4 °C, or 7 °C) on quality retention of meat and meat analogue sausage patties. Quality was determined using drip loss, color analysis, water activity, water holding capacity, headspace GC volatiles, proximate analysis (moisture, fat & protein), pH, texture analysis, sensory panel, total aerobic microorganisms, and cook yield.

Materials and Methods

The experiment was replicated three times during three different time periods using different sausage samples. There were 24 samples per replication for each sausage type divided among the 4 sampling times and the 3 storage temperatures, allowing duplicate samples at each sampling time for each sausage type. Frozen Jimmy Dean® Sausage, Beyond® Meat Sausage, and MorningStar® Farm Sausage samples were placed into 1 °C (plus or minus 2.1 °C), 4 °C (plus or minus 2.1 °C), or 7 °C (±2.4 °C) refrigerated storage and analyzed on days 0, 5, 10, and 15. Fig. 1 shows the outline of methods used for the experiment:

Fig. 1. Schematic of storage temperature effects on meat and meat analogue quality.

On day 0, color photographs of two sausage patties from each product type were taken using a Nikon (AF-P DX Nikkon Zoom 18–55 mm f.3.5-5.6G VR, Minato City, Tokyo, Japan) camera. The color of these same patties was then measured using the colorimeter, and patties were weighed to establish a baseline weight for future drip loss measurements. Color measurements were then taken using a Minolta CR-400 Chroma Meter handheld colorimeter (Ramsey, NJ) measuring the International Commission on Illumination (CIE) L* (lightness), a* (redness), and b* (yellowness) values at five locations. Before taking measurements, the spectrometer was calibrated with a standard white tile (L* = 56.95, a* = −21.94, b* = 10.06). The samples were blotted before the use of a colorimeter, and the colorimeter was cleaned between each sample with a clean wipe and ethanol spray to prevent contamination and interference errors. Chroma was calculated using values using the following equation: (1)Chroma=a2+b2

These samples were then placed on top of a traditional ice tray to collect drip lost during storage. Samples and trays were then labelled and placed in Ziploc Brand Gallon Freezer Bags in their respective refrigerators. A random pool of samples was collected for Day 0 testing while the remaining samples were placed in labelled Ziploc Brand Gallon Freezer Bags at refrigeration temperatures of 1 °C, 4 °C and 7 °C alongside a Testo brand (175H1, Titisee-Neustadt, Germany) sensor recording temperature and relative humidity each minute. The samples were then analyzed in duplicate for Headspace GC volatiles, water activity, total aerobic plate count, proximate analysis (moisture, fat, and protein content), pH and water holding capacity (WHC).

Volatile and semi-volatile organic compounds were measured using a Gas Chromatograph Mass Spectrometer Agilent Technologies 7697A headspace sampler (Santa Clara, CA). The analyses were conducted by placing 0.5 to 1 g of sample in a 250 µl flat bottom GC vial which was then inserted into the GC-MS. Prior to injections, samples were heated up to 260 °C and held for 10 minutes. A Front SS Inlet He Agilent 122-7032UI GC column (Santa Clara, CA) was used with a thermal profile of the oven at 72 °C to generate a chromatogram as seen in Fig. 2. Samples were analyzed further for specific volatile compounds at peak given using NIST software.

Fig. 2. Chromatogram example of beyond patty when stored at 7 °C.

Water activity was determined using two Rotronic Water Activity Meters (Rotronic, Zurich, Switzerland) that were connected to individual circulating water baths that maintained the sample chamber at 25 °C. Samples were placed in the chamber for a minimum of 30 minutes to equilibrate before water activity readings were recorded. The pH was determined on a homogenized sample that was prepared by weighing approximately 10 g of a sausage patty into a dual-range blender (Osterizer Pulse matic, Milwaukee, WI) containing 100 mL of distilled water. This mixture was then homogenized on the high setting in the Osterizer Pulse Matic on the blend setting for 1 minute. The pH of the blended sample was determined using a Thermo Orion 420A pH meter (Waltham, MA).

The number of total aerobic organisms was determined following the AOAC 990.12 method using 11 g of sample with 99 mL of PBS in Seward stomacher bag. Bags were then placed in Stomacher 4000 Circulator at 260 rpm for 2 minutes. Samples were analyzed on aerobic plate count (APC) and Escherichia. coli using E. coli/Coliform petrifilm (3 M Corporation, Saint Paul, MN) with dilutions from 100 to 102. Prior to testing for E. coli, samples were enriched by taking 1 mL of a sample and adding it to 30 mL tryptic soy broth. All petrifilm plates were incubated at 37 °C for 48 hours after which colonies were counted and results reported as log of the colony forming units per mL (log cfu/mL).

Water Holding Capacity (WHC) was determined according to the procedure described by Wardlaw et al. [7]. Approximately 10 g samples of meat were stirred for 1 minute with 15 mL of 0.6 M NaCl solution in a 45 mL centrifuge tube. The tube was then held at 4 °C for 15 minutes, stirred for 1 minute, then placed in a centrifuge (Centrifuge 5804 R Eppendorf AG, Hamburg, Germany) and centrifuged at 10,000 × g at 4 °C for 15 minutes. After centrifugation, the volume of the supernatant was measured using a 25 mL volumetric cylinder, and the results were reported as the proportion of the fluid retained by the sample according to the following equation: (2)WHC(%)=(Initial volume−volume of supernatantInitial volume)×100

Proximate analysis was performed in duplicate by weighing 25 g of the minced sample on a sample pan and placing it in the Stail-Therm Constant Temperature Cabinet (Blue M Electric Company, Blue Island, Illinois) to dry for 24 hours at 100 °C. Once dried, the sample was weighed again to calculate moisture content as seen below: (3)Moisture content (%)=(wet sample weight−dry sample weightwet sample weight)×100

The sample was then stored in a desiccator until it could be pulverized to produce a ground sample with a mortar and pestle. After grinding, samples were tested for fat and protein content. Protein was determined using the AOAC official Kjeldahl method 2001.11, and crude fat was determined using the AOAC official ether extract method 920.39. A separate set of stored samples were cooked in a convection oven at 177 °C for 8–9 minutes and flipped after 4 minutes in the oven until the patties reached an internal temperature of 74 °C. Two patties for each type and method were cooled for approximately 3 minutes and cut into 4 equal pieces then given to a trained cut into 4 equal pieces then given to a trained sensory panel for evaluation consisting of 6 to 8 judges using Fig. 3.

Fig. 3. Freshness quality guidelines for panelists evaluating sausage patties stored at different temperatures.

Following the panel, color analysis was performed again using the same samples to compare differences in color after cooking. Those samples were also weighed again to get cook yield and total loss of patty as seen in the equation below: (4)Cook yield=Cooked sample weightFresh sample weight×100

(5)Total Loss=(Drip Loss+(100−CookYield)100−thaw loss)×100

Statistical Analyses

Data were analyzed the general linear model procedure in PCSAS. The overall significance of sample type, storage temperature, and storage time, as well as the two-way and three-way interactions, were determined using the analysis of variance. Where overall treatments or treatment interactions were significant, means were separated using Tukey’s and least significant difference tests (p ≤ 0.05).

Results and Discussion

Storage temperature and storage time had minimal effect on volatile compound concentration. Twenty-three volatile compounds were identified in sausage samples via GC-MS analysis, with 20 volatile compounds having different peak areas (concentrations) between sausage samples (Table I). Beyond beef sausages had the highest concentration in 18 of the 20 volatiles identified. The majority of volatile compounds identified in the sausages are terpenes which are associated with spices and essential oils that are often used as fragrances and flavors. All three cooked sausage samples had detectable concentrations of α-terpineol, a flavor volatile that has been found in sausage volatile profiles by several other researchers [8]–[10]. Shiratsuchi et al. [11] identified various volatile compounds in non-fermented sausage and also separately in spices and liquid smoke used in sausage production. Compounds found in the spice mixture that were also detected in the samples tested in the current study include ethanol (except Jimmy Dean), α-pinene, 3-carene, d-limonene, p-cymene and α-terpineol. Furfural and camphor were detected in liquid smoke by these researchers and also found in all sausages. Thus, some of the differences in flavor volatiles between the types of sausage could be due to the proprietary spice ingredients. Furfural was detected in liquid smoke but not in the sausage mix without added smoke by Yoo et al. [12], further supporting that the differences in volatiles found in the current study may be caused by the added spice/smoke ingredients. Flores and Piornos [13] further identified α-pinene, 3-carene, and α-terpineol in spices used for fermented sausages. Schilling et al. [14] and the Flavor and Extract Manufacturing Association [15] were used to determine the various odor notes associated with several of the compounds found in the three types of sausage tested in the current study (Table I). Odor notes of some essential oil compounds, some of which were found in the present study, were further identified by Sekhar et al. [16] in a study to determine essential oil antimicrobial effects.

Sample Beyond Morningstar Jimmy dean Coefficient of variation (%) Odors identified
Peak area
Aldehydes and alcohols
Butanal 5484c 18761a 11833b 61 Green banana, pungent [15]
Ethanol 355662a 220990b ND 147 Sweet, alcohol [14]
Hexanal 13017a 7470b 5827b 54 Cut grass [14]
Furfural 11458a 8546a,b 5633b 25 Baked potato, bread, burnt [15]
α-pinene 52336a 13145c 21419b 32 Sausage, spicy [14]
Camphene 14681a 8178b 14320a 33 Camphor, oil, warm [15]
β phellandrene 35907a 19060b 13419c 33 Citrus, mint, pepper, spice [15]
Myrcene 39296a 34816b 23576c 33 Balsamic, fruit, mango, herb, [15], [16]
3-Carene 12115ab 3429b 5162b 25 Meaty, herbal [15], [16]
α phellandrene 4391a 2845b 2080c 30
D-Limonene 8829a 4791b 4043c 33 Citrus, mint [15], [16]
Eucalyptol 42545a 20238b 13397c 33 Camphor, cool, mint [15]
Terpinene 45599a 37511b 19266c 24 Pine [15]
p-cymene 3496a 2354b 1835b 27 Citrus, fresh [15]
Caryophyllene 45134a 10794c 25407b 101 Fried, spice, wood [15]
α-terpineol 8169a 4180b 2339c 29 Minty [14]
Fenchone 156261b 155598b 711357a 166 Minty, cool, floral [15]
Camphor 11458a 13197c 19746b 70 Earth, pine, spice [15]
Acetoin (ketone) 9478a 4106b 3124c 30 Butter, green pepper [15]
Anethole (aromatic) 46735a 9668b 611c 35 Anise [15]
Table I. GC Volatile Peak Areas for Cooked Patties for Each Sample Type

Table II shows the average temperature and relative humidity data collected by the Testo sensors for each trial over the sampling days. The target refrigeration temperatures were 1 °C, 4 °C, and 7 °C, and relative humidity was also recorded. The 4 °C refrigerator was the least consistent in holding temperature throughout the experiment compared to 1 and 7 °C refrigerator temperatures (Table II). Trials were conducted simultaneously within 7 days of one another, so variation was expected. Refrigerators were opened for approximately 30 seconds each sampling day to collect samples for each testing day.

Trial Expected temperature (°C) Average relative humidity (%) Average temperature (°C)
1 1 46.1 (11.5)1 1.0 (0.47)
4 44.7 (11.9) 3.8 (0.52)
7 32.7 (8.4) 6.6 (0.50)
2 1 47.6 (11.9) 0.9 (0.50)
4 47.0 (11.9) 3.2 (1.00)
7 33.6 (8.1) 6.8 (0.46)
3 1 46.5 (11.5) 0.9 (0.50)
4 45.8 (11.8) 3.0 (1.11)
7 32.6 (7.98) 7.1 (0.40)
Table II. Average Internal Relative Humidity and Temperature Data for Refrigerators During 7 Days of Storage

The range for relative humidity during storage for 1 °C, 4 °C, and 7 °C were 19.9% to 99.9%, 19.2% to 99.9%, and 20.5% to 99.9%, respectively. Range for temperature during storage for 1 °C, 4 °C and 7 °C were −0.5 °C to 5.1 °C, −1.2 °C to 7.1 °C, and 4.6 °C to 9.2 °C, respectively.

Morningstar sausage had the lowest L* value with the highest a*, b*, and chroma value, while Beyond Beef sausage had the highest L* value with the lowest a*, b*, and chroma value (Table III) with L* and a* values highest on day 0. Thus, patties on day 0 had the lightest and most red color, which could be due to ice formation that protected the surfaces of patties and the freshness of samples. There was no significant difference on days 5, 10, and 15 among the samples in terms of L* value, with a* and b* values trending down during storage (Table III), likely due to the iciness from removing the patties from the freezer. Beyond Beef sausage had significantly the highest drip loss and water activity, while Morningstar sausage had the lowest, possibly due to soy and wheat protein interactions (Table III). As previously stated, a lower thaw loss is associated with a lower risk of microbial contamination [17]. WHC was largely affected by the sample type, as Beyond Beef patties had the highest WHC, and Jimmy Dean patty had the lowest WHC (Table III) [7].

Sample Drip loss (%) L*1 a*2 b*3 Chroma pH WHC4 Moisture (%) Fat (%) Protein (%) Ash (%)
B 0.9a 55.3a 4.7c 17.3c 17.9c 6.49b 55.2a 51.8c 19.5b 18.3b 1.7a
(±1.35) (±3.97) (±0.58) (±1.00) (±1.10) (±0.46) (±7.69) (±3.08) (±2.03) (±1.23) (±1.75)
Morn 0.0b 35.1c 10.4a 22.7a 25.0a 6.23c 49.7b 54.6b 2.9c 24.9a 1.0b
(±0.60) (±2.48) (±2.23) (±2.40) (±2.89) (±0.07) (±3.93) (±1.64) (±1.42) (±0.84) (±0.43)
JD 0.5a,b 51.7b 7.4b 20.9b 22.2b 6.68a 49.0b 58.0a 21.9a) 13.5c 0.8b
(±2.02) (±3.14) (±1.02) (±1.37) (±1.56) (±0.11) (±6.30) (±3.53) (±2.23) (±1.05) (±0.71)
Table III. Quality Parameter Results for Patties for Each Sample Type

Based on nutritional labels, Morningstar sausages should have the highest protein and lowest fat content, while Jimmy Dean sausages should have the lowest protein and highest fat content, as confirmed by our analysis (Table III). Jimmy Dean patties had the highest moisture content, and Beyond patties had the lowest (Table III). Jimmy Dean sausage has the highest sodium content with 570 mg of sodium, which may facilitate moisture retention, and Beyond Beef sausage has the lowest sodium content with 270 mg of sodium. Salt attracts moisture into foods as it is hygroscopic, meaning it is able to absorb water and moisture from air due to its net positive charge, which attracts the net negative charge from water [18]. Moisture content was similar amongst the first three sampling days, but the last day was significantly higher than other days (Table IV). An increase in moisture (data not shown) and the appearance of mould on some pa were observed on Day 15. High moisture content allows for a favorable environment for microbial growth [19]. No change in proximate composition was observed during storage at different temperatures, as expected. The cumulative drip loss increased during storage, yet the greater effect on these parameters was due to sausage type (Tables III, IV). Drip loss and water activity were expected to increase during storage, which was mirrored by increased microbial growth (data not shown). However, it should be noted that water holding capacity did not follow a specific trend during storage.

Day Drip loss (%) L*1 a*2 b*3 pH WHC4 Moisture (%) Fat (%) Ash (%)
0 0.0b 48.7a 7.8a 20.0b 6.54a 49.7b 54.2b 14.9a,b 1.4a
(±0.00) (±2.21) (±0.61) (±1.00) (±0.04) (±5.88) (±2.43 (±1.33) (±0.70)
5 0.0b 46.8b 7.7a,b 20.7a 6.51a 53.4a 54.0b 14.4b 1.7a
(±1.43) (±8.55) (±2.68) (±2.91) (±0.27) (±6.55) (±4.81) (±8.90) (±1.84)
10 0.6a,b 47.0b 7.3b 20.4a,b 6.50a 50.2b 54.7b 15.3a 0.9b
(±0.79) (±8.39) (±2.64) (±2.84) (±0.32) (±7.20) (±3.77) (±9.20) (±1.04)
15 1.1a 47.0b 7.1b 20.1b 6.32b 52.7a,b 56.3a 14.4b 0.6b
(±2.35) (±8.23) (±2.75) (±3.04) (±0.43) (±4.89) (±2.55) (±8.87) (±0.40)
Table IV. Quality Parameter Results for Patties Based on Storage Days

Storage temperature significantly affected both a* and hue values with an inverse relationship between a* values and refrigeration temperature, with the highest temperature (7 °C) having the lowest a* values and the lowest temperature (1 °C) having the highest a* values (Table V). The lower a* values for higher temperatures can be attributed to the oxidation of myoglobin that reduces redness in meat in Jimmy Dean and Beyond brand samples since they both contain myoglobin [20]. Furthermore, patty color differed more due to sausage type than storage temperature or sampling time (Tables V, VI).

Day Sample L*1 a*2 b*3 Chroma pH WHC4 Moisture (%) Fat(%) Ash(%)
0 Beyond 61.3a 5.1d 18.1e 18.8c 6.72a 55.2a,b,c 50.5f 20.2b,c 1.9b
(±2.21) (±0.61) (±1.00) (±1.11) (±0.04) (±5.88) (±2.21) (±1.33) (±0.92)
0 Morningstar 33.4d 11.2a 22.1a,b,c 24.8a 6.62b 50.7b,c,d 54.5d 4.1e 1.3b,c,d
(±2.51) (±2.11) (±2.88) (±3.37) (±0.06) (±5.03) (±1.58) (±2.02) (±0.18)
0 Jimmy Dean 51.5b,c 7.0c 19.7d 21.0b 6.69a 43.3e 57.7a,b,c 20.4b,c 0.9c,d
(±3.80) (±0.89) (±1.65) (±1.81) (±0.08) (±6.61) (±1.70) (±3.56) (±0.34)
5 Beyond 54.1b 5.1d 17.5e,f 18.2c 6.71a 59.3a 51.5e,f 18.2d 3.0a
(±2.07) (±0.25) (±0.33) (±0.37) (±0.19) (±4.43) (±3.83) (±2.75) (±2.48)
5 Morningstar 35.5d 10.4a,b 23.4a 25.6a 6.20b 49.6c,d 53.8d,e 2.5e,f 0.9c,d
(±2.03) (±2.44) (±2.47) (±3.08) (±0.09) (±3.89) (±1.49) (±1.02) (±0.35)
5 Jimmy Dean 50.9c 7.6c 21.3b,c 22.6b 6.63a 51.1b,c,d 56.5b,c,d 22.6a 1.2b,c,d
(±3.33) (±1.06) (±1.16) (±1.38) (±0.14) (±6.39) (±6.49) (±1.69) (±1.22)
10 Beyond 53.1b,c 4.6d 17.1e,f 17.7c 6.51a 50.3b,c,d 50.8f 20.8a,b 1.5b,c
(±1.69) (±0.27) (±0.49) (±0.52) (±0.42) (±11.75) (±2.67) (±1.48) (±1.57)
10 Morningstar 35.6d 9.9a,b 22.7a,b 24.8a 6.26b 50.2b,c,d 54.6d 2.7e,f 0.9c,d
(±2.27) (±2.22) (±2.24) (±2.75) (±0.04) (±3.17) (±1.60) (±0.84) (±0.37)
10 Jimmy Dean 52.2b,c 7.5c 21.3b,c 22.6b 6.75a 50.2b,c,d 58.8a,b 22.5a 0.4d
(±2.64) (±1.02) (±0.97) (±1.19) (±0.05) (±3.22) (±0.90) (±0.89) (±0.13)
15 Beyond 52.9b,c 4.2d 16.5f 17.0c 6.02b 55.8a,b 54.4d 18.8c,d 0.5d
(±1.57) (±0.49) (±1.21) (±1.27) (±0.57) (±3.23) (±1.32) (±0.92) (±0.17)
15 Morningstar 35.9d 9.9a,b 22.6a,b,c 24.7a 6.26b 48.2d,e 55.3c,d 2.2f 0.9c,d
(±2.42) (±2.03) (±1.95) (±2.43) (±0.08) (±3.20) (±1.70) (±0.60) (±0.57)
15 Jimmy Dean 52.3b,c 7.4c 21.1c,d 22.3b 6.67a 51.3b,c,d 59.2a 22.3a 0.5d
(±2.67) (±1.10) (±0.98) (±1.26) (±0.13) (±4.96) (±1.12) (±0.98) (±0.21)
Table V. Quality Parameter Results for Temperature for Each Patty Types at 0, 5, 10, and 15 Days
Temperature (°C) Sample L*1 b*2 pH
1 Beyond 56.1a 17.8e 6.74a
(±2.66) (±1.18) (±0.05)
1 Morningstar 33.6d 21.9b,c 6.24d
(±2.40) (±1.94) (±0.07)
1 Jimmy Dean 52.2b,c 21.1c,d 6.70a,b
(±2.13) (±1.37) (±0.09)
4 Beyond 55.9a 17.2e 6.48b,c
(±1.47) (±0.98) (±0.05)
4 Morningstar 35.4d 23.3a 6.24d
(±2.23) (±4.00) (±0.07)
4 Jimmy Dean 52.1b,c 21.1c,d 6.69a,b
(±0.73) (±1.50) (±0.09)
7 Beyond 54.0a,b 16.9e 6.26c,d
(±3.43) (±1.36) (±0.59)
7 Morningstar 36.3d 22.9a,b 6.23d
(±1.59) (±2.51) (±0.08)
7 Jimmy Dean 51.0c 20.5d 6.66a,b
(±4.62) (±1.49) (±0.13)
Table VI. Quality Parameter Results for Patty Types Stored at 1 °C, 4 °C, and 7 °C

Sample type was the greatest contributor to differences in moisture and chemical properties (Tables V, VI). When pH was compared among all patties, Morningstar had the lowest pH; furthermore, pH decreased during storage (Table V) and decreased with higher refrigeration temperatures (Table VI). The closer the pH is to the isoelectric point (pI) of proteins, the lower the water-holding capacity [21]. Lower pH can equate to a darker appearance as it causes less light to be reflected, but this may not be the case for meat analogues since different proteins have different isoelectric points. Proteins in Beyond Beef patties include peas, fava beans, and rice, which have a pI in the 4 to 5.5 range, while the protein sources used in Morningstar sausage are wheat gluten (pI = 6.4) and soy protein (pI = 4.5). Soy addition dramatically decreased free water related to syneresis, suggesting a competition for water between soy proteins and gluten proteins [22]. Thus, the lower thaw loss for the Morningstar patties may be due to this soy-wheat protein interaction.

Samples stored at the higher storage temperature (7 °C) resulted in a significantly lower pH (Table VI) and higher aerobic plate counts (Fig. 4) as compared to other storage temperatures. Patties stored at 7 °C would be considered spoiled, achieving 6 log cfu/g total aerobic microorganisms after 10 days of storage, while patties stored at 4 °C required 15 days of storage to achieve counts of microorganisms approaching spoilage. Patties stored at 1 °C would not be considered spoiled even after 15 days of storage (Fig. 4). Individually, all three sausage types stored at 1 °C remained below 5 log cfu/g for 15 days of storage, while each sausage type stored at 7 °C reached over 6 log cfu/g after 15 days of storage (data not shown).

Fig. 4. Log cfu/g of total aerobic microorganisms for all sausage types grouped together stored at 1 °C, 4 °C, or 7 °C over 15 days.

The nutritional label states that one patty (38 g) of Morningstar sausage has 3 g of fat (7.9%) and 9 g of protein (23.7%), two patties (58 g total) of Beyond Beef sausage has 12 g of fat (20.7%) and 11 g of protein (19.0%), and two patties (53 g total) of Jimmy Dean sausage has 20 g of fat (37.7%) and 6 g of protein (11.3%).

In terms of sensory, there was only a significant difference in appearance and overall appeal amongst samples (Table VII). Morningstar patties had the highest mean score for appearance and overall appeal, whereas Beyond Beef patties had the lowest. Storage temperature had little to no effect on the sensory perception among panelists. Jimmy Dean sausage had the highest pH compared to Beyond Beef and Morningstar sausage (Table VII), which can be attributed to acidity from pea and soy protein, respectively [23]. Morningstar patties had the highest cook yield, while Beyond Beef patties had the lowest, indicating Morningstar patties retained moisture to a greater extent during cooking compared to other patty samples [24]. As stated previously, there is an inverse relationship between refrigeration temperature and pH (Table VIII), which is attributed to increased microbial growth.

Sample pH Appear1 Overall1 Hardness (g/mm2) Compressi-bility Adhesiveness (g.sec) Cohesiveness Cook yield (%) Total loss (%)
Beyond 6.11b 1.6b 1.9b 34.6b 76.6b −1.4a −0.05a 73.5c 27.6a
(±0.51) (±1.01) (±1.13) (±6.61) (±14.61) (±6.80) (±0.17) (±2.29) (±2.46)
Morningstar 6.21b 4.0a 3.1a 46.8a 121.4a −9.8c −0.21c 95.5a 4.6c
(±0.10) (±0.94) (±1.41) (±6.32) (±18.66) (±2.51) (±0.05) (±0.65) (±0.48)
Jimmy Dean 6.60a 2.3b 2.7a 37.5b 135.4a −6.1b −0.17b 93.5b 6.8b
(±0.21) (±1.37) (±1.41) (±6.99) (±20.46) (±2.59) (±0.07) (±1.57) (±1.67)
Table VII. Quality Parameter Results for Cooked Patties for Each Sample Type
Temperature (°C) pH Hardness (g/mm2) Compressibility Cook yield (%)
1 6.54a 40.7a,b 115.3a,b 87.0b
(±0.07) (±5.35) (±10.30) (±1.53)
4 6.31b 35.9b 101.7b 88.1a
(±0.12) (±4.58) (±13.24) (±2.47)
7 6.07c 42.3a 116.4a 87.3a,b
(±0.42) (±8.91) (±33.65) (±9.38)
Table VIII. Quality Parameter Results for Cooked Patties for Each Storage Temperature

Beyond Beef, sausage had the highest values for adhesiveness and cohesiveness. However, Morningstar sausage had the highest hardness value. Morningstar sausages had the lowest adhesiveness and cohesiveness, while Beyond Beef sausage had significantly lower compressibility/springiness (Table VII). Temperature had little effect on texture except in terms of hardness and compressibility, as higher temperatures resulted in harder and more compressible samples (Table VIII), likely due to lower moisture retention of samples. The 4 °C refrigeration temperature had the lowest values for hardness and compressibility, which signified a juicier sample. Interestingly, despite the variability and significance differences among the patty types, texture in the sensory panel was not significantly different (Table VII).


Refrigeration at 7 °C resulted in the lowest quality sausage, while storage at 1 °C was found to have the highest quality sausage. Samples that were subjected to a storage temperature of 7 °C had significantly lower value, hardness, and compressibility that resulted in a patty that was less redness, less tender, and stickier. This was reflected in a less desirable sample visually and textually compared to other treatments. Furthermore, microbial growth was more rapid at 7 °C than expected, possibly resulting in lower-quality sensory assessment. Samples in 1 °C refrigeration were seen as higher quality due to higher a* value and significantly higher cook yield. High a* value is associated with a better-quality meat sample and higher cook yield represents less loss of fat, moisture and flavor during cooking. Moreover, 1 °C had the slowest growth of microorganisms among the other refrigeration temperatures. Additionally, refrigeration at 4 °C was found to have the best textural properties, as seen through texture profile analysis, by having significantly lower hardness and springiness values, indicating a more tender and less sticky sample for better mouthfeel.

The sample type was the largest indicator of quality, with Morningstar patties having the most favorable results reflected by moisture content and sensory data. Morningstar patties had nearly double the scores for appearance compared to Beyond Beef sausage, while both Morning Star and Jimmy Dean patties had significantly higher cook yield and significantly lower cooking loss, drip loss, and total loss compared to Beyond sausage. Further research on the relationship between energy conservation and refrigeration temperatures for prolonged shelf life of sausage analogues would be beneficial to ensure reduced costs and consumer safety as refrigerators set at 7 °C use roughly 15% less energy (kWh/day) compared to 4 °C and 36% less energy compared to 1 °C [25], On a related note, Nomad Foods (owner of Bird’s Eye, Findus and Igloo brands) is conducting research to raise the frozen storage temperature from −18 °C to −15 °C which would reduce energy usage by approximately 10% [26].


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