Mahesh Narayanan Nair

Continued evaluation of novel antimicrobial treatments or chemical formulations remains crucial for controlling pathogen contamination on carcasses during beef processing. This study evaluated the antimicrobial effects of on-site generated alkaline peroxyacetic acid (ALK-PAA) against Shiga toxin-producing Escherichia coli (STEC) and Salmonella enterica on beef carcass surface tissue, and compared them with those of peroxyacetic acid (PAA) and lactic acid (LA). Adipose tissue, collected from the surface of prerigor carcasses after hide removal and prior to antimicrobial intervention, was cut into 10 × 10-cm sections and surface-inoculated (ca. 6 log colony-forming units [CFU]/cm 2 ) with multistrain mixtures of STEC or Salmonella. Inoculated samples (n = 6) were spray treated (10–12 s, 117–138 kPa) with 400 ppm ALK-PAA, 400 ppm PAA, 4% LA, or water using a laboratory-scale spray cabinet. Untreated samples served as controls. Following treatment, samples were analyzed for surviving populations using selective and nonselective differential culture media to determine antimicrobial efficacy and to assess potential sublethal cell injury. Compared with the untreated controls, all chemical interventions reduced (P < .05) STEC and Salmonella populations. The antimicrobial effects of ALK-PAA and PAA were comparable (P ≥ .05), regardless of recovery agar, reducing STEC and Salmonella by 1.5 to 1.7 and 1.2 to 1.6 log CFU/cm2, respectively. For LA-treated samples, greater (P < .05) recovery of STEC (by 0.6 log CFU/cm2) and Salmonella (by 0.9 log CFU/cm2) on nonselective media than on selective media indicated the presence of sublethally injured cells. Overall, ALK-PAA was an effective antimicrobial intervention under the conditions evaluated against STEC and Salmonella on beef carcass surface adipose tissue.

Background/Objectives: Early postmortem mitochondrial function and apoptotic activation affect meat quality development. Nicotinamide riboside (NR) supplementation to pigs prior to harvest can improve pork color stability, but its mechanism remains unclear. This study aimed to evaluate the impact of NR supplementation on early postmortem mitochondrial functionality and apoptosis. Methods: Sixteen pigs (N = 16) were individually fed a control or NR-supplemented diet (30 mg·kg body weight⁻¹·d⁻¹) for 10 days prior to harvest. Longissimus dorsi muscle samples were collected at 45 min and 24 h postmortem and analyzed for mitochondrial functionality using high-resolution respirometry and apoptotic protein abundance (apoptosis regulator Bcl-2-associated X (BAX), apoptotic inducing factor (AIF), and caspase 3 (CASP3)) via immunoblotting. Results: NR-supplemented muscle exhibited lower proton leak-associated respiration at 45 min postmortem (p < 0.05), followed by a slower accumulation of mitochondrial outer membrane permeabilization (MOMP; p < 0.05) and a slower loss of mitochondrial integral function (p < 0.05) from 45 min to 24 h postmortem. NR supplementation decreased BAX abundance at 45 min postmortem but increased mature AIF abundance (62 kDa) at 24 h postmortem (p < 0.05). The abundance of CASP3 fragments (~29 kDa) decreased from 45 min to 24 h postmortem, independent of treatment (p < 0.05). Conclusions: NR supplementation demonstrated the potential to protect mitochondrial integral function and alleviate apoptotic activation in early postmortem porcine skeletal muscle, which might contribute to a higher meat color stability in NR-supplemented pork during retail display.

Rapid evaporative ionization mass spectrometry (REIMS) is an ambient ionization mass spectrometry technique that enables real-time evaluation of several complex traits from a single measurement. The objectives of this study were: (1) to investigate the capability of REIMS to accurately identify and predict sheep carcass characteristics and flavor based on consumer response utilizing data acquired by I-Knife, and (2) to compare the ability of 2 electrodes (Meat Probe vs. I-Knife) to differentiate carcass characteristics and cooked meat flavor. For objective 1, 200 sheep carcasses were used to generate I-Knife REIMS data from the external fat and the surface lean of the Biceps femoris muscle (45 min postmortem) as well as meat patties (7 d postmortem). These patties were further used to evaluate consumer preferences using sensory analysis. Objective 2 was achieved by comparing the predictive performance of I-Knife and Meat Probe REIMS data collected from meat patties. The results demonstrated that REIMS analysis of raw meat samples can be used to accurately predict and classify cooked sheep meat flavor and carcass characteristics. Specifically, the lean and fat tissue collected at 45 min postmortem can be used to predict carcass characteristics and postrigor meat flavor. Models for diet, flavor intensity acceptance, off-flavor presence, overall acceptance, age, and flavor acceptance achieved prediction accuracy higher than 80%. In addition, models generated using data from the Meat Probe had similar or better prediction accuracies for carcass background (age, diet, and gender) and consumer preference (intensity acceptance, flavor acceptance, off-flavor presence, and overall acceptance) compared to models based on the I-Knife data. Overall, these results demonstrated the potential for REIMS to predict and classify cooked sheep meat flavor accurately and validated the use of the Meat Probe for REIMS analysis.

Beef whole-muscle cuts containing biceps femoris (BF) exhibit inferior tenderness compared to cuts from the ribs and loins. The BF is a sizeable muscle in beef round, and enhancing tenderness of BF may increase the value of beef carcasses. While wet aging for 21 d improves beef tenderness, it can compromise color. Therefore, we evaluated the effects of wet aging on color and tenderness of beef BF to identify an optimal aging duration for these quality traits. The BF muscles were collected 24 h postmortem from 8 beef carcasses (n = 8), divided into equal sections, vacuum packaged, and aged at 2°C for 0, 7, 14, and 21 d. After aging, muscle sections were fabricated into steaks, overwrapped, and stored for 0, 3, or 6 d under refrigerated storage. Myoglobin concentration, shear force, pH, instrumental color, metmyoglobin reducing activity (MRA), and lipid oxidation were evaluated. Beef BF steaks aged for 21 d exhibited lower (P < .05) shear force than those aged for 0, 7, and 14 d indicating an increased tenderness. Additionally, the 7- and 14-d aged steaks demonstrated lower (P < .05) shear force than their nonaged counterparts. The BF muscles aged for 14 and 21 d exhibited lower (P < .05) myoglobin concentration compared to those aged for 0 and 7 d. Aged BF steaks (7, 14, and 21 d) demonstrated greater (P < .05) redness on days 0 and 3 of storage than the nonaged ones. Overall, MRA and color stability were not affected (P > .05) by aging, whereas lipid oxidation increased (P < .05) with aging and storage days. The results indicated that 21 d of wet aging could be a practical strategy to improve the tenderness of BF steaks without compromising the surface color.

This study evaluated the effect of sous vide cooking at different temperatures and dwell times (1A: 56.1°C and 71 min; 1B: 56.1°C and 150 min; 1C: 56.1°C and 240 min; 2A: 61.7°C and 8 min; 2B: 61.7°C and 150 min; 2C: 61.7°C and 240 min) on palatability of beef biceps femoris. Beef biceps femoris ([USDA] Choice) was sliced into 1.6-cm thick steaks, and multiple steaks were vacuum packaged as 4.5 kg bags and randomly assigned to one of the 6 treatments with 16 packages (n = 16) per treatment. Cook loss during sous vide cooking was measured. Cooked steaks were used for internal cooked color measurement, Warner-Bratzler shear force (WBSF) evaluation, and trained sensory analysis. Data were analyzed using a complete randomized design in R. Cooking loss of samples increased as the temperature and dwell time combinations increased (P < 0.05). On the other hand, the internal redness of steaks decreased (P < 0.05) with increased temperature and dwell time. The 1C samples had numerically lower WBSF values and higher perceived tenderness scores (P < 0.05) than the 2A samples. These results indicate that beef biceps femoris steaks can be cooked under the conditions examined in this study with minimal impact on palatability, allowing processors to optimize sous vide cooking parameters.

Iron is an essential mineral that supports biological functions like growth, oxygen transport, cellular function, and hormone synthesis. Insufficient dietary iron can lead to anemia and cause fatigue, cognitive impairment, and poor immune function. Animal-based foods provide heme iron, which is more bioavailable to humans, while plant-based foods typically contain less bioavailable non-heme iron. Edible insects vary in their iron content and may have heme or non-heme forms, depending on their diet. Edible insects have been proposed as a protein source that could address issues of food insecurity and malnutrition in low resource contexts; therefore, it is important to understand the bioavailability of iron from insect-based foods. In this study, we used Inductively Coupled Plasma and Mass Spectrometry (IPC-MS) and Caco-2 cell culture models to compare the soluble and bioavailable iron among five different lab-produced tempeh formulations featuring Tenebrio molitor (mealworm) with their non-fermented raw ingredient combinations. Finally, we compared the iron bioavailability of a mealworm tempeh with two sources of conventional beef (ground beef and sirloin steaks) and two commercially available plant-based meat alternatives. The results show that while plant-based meat alternatives had higher amounts of soluble iron, particularly in the Beyond Burger samples, the fermented mealworm-based tempeh had greater amounts of bioavailable iron than the other samples within the set. While all the samples presented varying degrees of iron bioavailability, all products within the sample set would be considered good sources of dietary iron.

The objective was to understand the impacts of secondary lipid oxidation products on calpain-2 activity and autolysis and, subsequently, to determine the quantity and localization of modification sites. 2-Hexenal and 4-hydroxynonenal incubation significantly decreased calpain-2 activity and slowed the progression of autolysis, while malondialdehyde had minimal impact on calpain-2 activity and autolysis. Specific modification sites were determined with LC-MS/MS, including distinct malondialdehyde modification sites on the calpain-2 catalytic and regulatory subunits. 2-Hexenal modification sites were observed on the calpain-2 catalytic subunit. Intact protein mass analysis with MALDI-MS revealed that a significant number of modifications on the calpain-2 catalytic and regulatory subunits are likely to exist. These observations confirm that specific lipid oxidation products modify calpain-2 and may affect the calpain-2 functionality. The results of these novel experiments have implications for healthy tissue metabolism, skeletal muscle growth, and post-mortem meat tenderness development.

The prevalence of highly marbled cattle breeds, such as Wagyu, has increased in the US due to consumer demand for higher-quality beef. The ability to grade highly marbled carcasses accurately and consistently, particularly with quantifying intramuscular fat content for validation, remains a challenging task for the Wagyu beef industry. New camera grading technologies have been proposed by VIAS VBG 2000 (e+v Technology GmbH & Co. KG, 2021), Meat Image Japan (MIJ), and MasterBeef (MB) for Wagyu-influenced beef carcass assessment based on advanced image analysis. However, the intramuscular fat measurements of these camera technologies and the actual percent intramuscular fat (%IMF) in the longissimus at the 12/13th rib have yet to be investigated. Chilled carcasses (n = 173) from F1 Wagyu cattle were ribbed between the 12th and 13th ribs, and the left carcass sides were imaged with the E+V, MIJ, and MB cameras. Additionally, the marbling score was assigned by a team of 3 US Department of Agriculture (USDA) graders. Samples from the longissimus thoracis were collected, and the %IMF of the muscle was determined in triplicate. Linear regressions and descriptive statistics were done using JMP (Statistical Discovery, NC, USA) software. Camera fat-related measurements were linearly correlated, and R2 was calculated. The E+V camera had the highest %IMF predictability of all cameras (P < 0.0001) using the marbling score (R2 = 0.6450) estimate. The MIJ camera presented prediction accuracy between the other 2 technologies (P < 0.0001) of %IMF with identical R2 for fat percent and fat score estimates (R2 = 0.5952). The MB camera had the lowest predictability (P < 0.0001) of %IMF using the measured marbling score (R2 = 0.3269), marbling area (R2 = 0.3333), and marbling percent (R2 = 0.3269) estimates from the instrument. As technology advances, new technologies will provide alternative means for grading Wagyu-influenced carcasses. Additionally, these findings could aid the implementation of the USDA pilot program for remote carcass grading.