Cross-protection against influenza viruses by chimeric M2e-H3 stalk protein or multi-subtype neuraminidase plus M2e virus-like particle vaccine in ferrets

Current influenza vaccine is not effective in providing cross-protection against variants. We evaluated the immunogenicity and efficacy of multi-subtype neuraminidase (NA) and M2 ectodomain virus-like particle (m-cNA-M2e VLP) and chimeric M2e-H3 stalk protein vaccines (M2e-H3 stalk) in ferrets. Our results showed that ferrets with recombinant m-cNA-M2e VLP or M2e-H3 stalk vaccination induced multi-vaccine antigen specific IgG antibodies (M2e, H3 stalk, NA), NA inhibition, antibody-secreting cells, and IFN-γ secreting cell responses. Ferrets immunized with either m-cNA-M2e VLP or M2e-H3 stalk vaccine were protected from H1N1 and H3N2 influenza viruses by lowering viral titers in nasal washes, trachea, and lungs after challenge. Vaccinated ferret antisera conferred broad humoral immunity in naïve mice. Our findings provide evidence that immunity to M2e and HA-stalk or M2e plus multi-subtype NA proteins induces cross-protection in ferrets.

Heterologous Prime-Boost Vaccination with Inactivated Influenza Viruses Induces More Effective Cross-Protection than Homologous Repeat Vaccination

With concerns about the efficacy of repeat annual influenza vaccination, it is important to better understand the impact of priming vaccine immunity and develop an effective vaccination strategy. Here, we determined the impact of heterologous prime-boost vaccination on inducing broader protective immunity compared to repeat vaccination with the same antigen. The primed mice that were intramuscularly boosted with a heterologous inactivated influenza A virus (H1N1, H3N2, H5N1, H7N9, H9N2) vaccine showed increased strain-specific hemagglutination inhibition titers against prime and boost vaccine strains. Heterologous prime-boost vaccination of mice with inactivated viruses was more effective in inducing high levels of IgG antibodies specific for groups 1 and 2 hemagglutinin stalk domains, as well as cross-protection, compared to homologous vaccination. Both humoral and T cell immunity were found to play a critical role in conferring cross-protection by heterologous prime-boost vaccination. These results support a strategy to enhance cross-protective efficacy by heterologous prime-boost influenza vaccination.

Hemagglutinin virus-like particles incorporated with membrane-bound cytokine adjuvants provide protection against homologous and heterologous influenza virus challenge in aged mice

BACKGROUND

Current influenza vaccines deliver satisfactory results in young people but are less effective in the elderly. Development of vaccines for an ever-increasing aging population has been an arduous challenge due to immunosenescence that impairs the immune response in the aged, both quantitatively and qualitatively.

RESULTS

To potentially enhance vaccine efficacy in the elderly, we investigated the immunogenicity and cross-protection of influenza hemagglutinin virus-like particles (HA-VLP) incorporated with glycosylphosphatidylinositol (GPI)-anchored cytokine-adjuvants (GPI-GM-CSF and GPI-IL-12) via protein transfer in aged mice. Lung viral replication against homologous and heterologous influenza viruses was significantly reduced in aged mice after vaccination with cytokine incorporated VLPs (HA-VLP-Cyt) in comparison to HA-VLP alone. Enhanced IFN-γ⁺CD4⁺ and IFN-γ⁺CD8⁺ T cell responses were also observed in aged mice immunized with HA-VLP-Cyt when compared to HA-VLP alone.

CONCLUSIONS

Cytokine-adjuvanted influenza HA-VLP vaccine induced enhanced protective response against homologous influenza A virus infection in aged mice. Influenza HA-VLP vaccine with GPI-cytokines also induced enhanced T cell responses correlating with better protection against heterologous infection in the absence of neutralizing antibodies. The results suggest that a vaccination strategy using cytokine-adjuvanted influenza HA-VLPs could be used to enhance protection against influenza A virus in the elderly.

Protective Immunity Induced by Immunization with Baculovirus, Virus-like Particle, and Vaccinia Virus Expressing the AMA1 of Plasmodium berghei

Heterologous prime–boost immunization regimens using various vaccine platforms demonstrated promising results against infectious diseases. Here, mice were sequentially immunized with the recombinant baculovirus (rBV), virus-like particle (VLP), and recombinant vaccinia virus (rVV) vaccines expressing the Plasmodium berghei apical membrane antigen 1 (AMA1) for protective efficacy evaluation. The rBV_V_rVV heterologous immunization regimen elicited high levels of parasite-specific IgG, IgG2a, and IgG2b antibody responses in sera. Upon P. berghei challenge infection, proliferations of germinal center B cells in the inguinal lymph nodes, as well as blood CD4+ and CD8+ T cells were induced. More importantly, rBV_V_rVV immunization significantly diminished the parasitemia and prevented drastic bodyweight loss in mice post-challenge infection with P. berghei. Our findings revealed that immunization with rBV, VLP, and rVV expressing the AMA1 conferred protection against P. berghei infection, providing evidence for the potential implementation of this strategy.

Impact of hemagglutination activity and M2e immunity on conferring protection against influenza viruses

To improve cross-protection of influenza vaccination, we tested conjugation of conserved M2e epitopes to the surface of inactivated influenza virus (iPR8-M2e*). Treatment of virus with chemical cross-linker led to diminished hemagglutination activity and failure to induce hemagglutination inhibiting antibodies. Conjugated iPR8-M2e* vaccine was less protective against homologous and heterosubtypic viruses, despite the induction of virus-specific binding IgG antibodies. In alternative approaches to enhance cross-protection, we developed a genetically linked chimeric protein (M2e-B stalk) vaccine with M2e of influenza A and hemagglutinin (HA) stalk of influenza B virus. Vaccination of mice with inactivated influenza A virus supplemented with M2e-B stalk effectively induced hemagglutination inhibiting antibodies, humoral and cellular M2e immune responses, and enhanced heterosubtypic protection. This study demonstrates the importance of HA functional integrity in influenza vaccine efficacy and that supplementation of influenza vaccines with M2e-B stalk protein could be a feasible strategy of improving cross-protection against influenza viruses.

Adjuvant Effects of a New Saponin Analog VSA-1 on Enhancing Homologous and Heterosubtypic Protection by Influenza Virus Vaccination

Adjuvants can increase the magnitude and durability of the immune response generated by the vaccine antigen. Aluminum salts (Alum) remain the main adjuvant licensed for human use. A few new adjuvants have been licensed for use in human vaccines since the 1990s. QS-21, a mixture of saponin compounds, was included in the AS01-adjuvanted Shingrix vaccine. Here, we investigated the adjuvant effects of VSA-1, a newly developed semisynthetic analog of QS-21, on promoting protection in mice after vaccination with the inactivated split virus vaccine. The adjuvant effects of VSA-1 on improving vaccine efficacy after prime immunization were evident as shown by significantly higher levels of hemagglutination-inhibiting antibody titers and enhanced homologous protection compared to those by QS-21 and Alum adjuvants. The adjuvant effects of VSA-1 on enhancing heterosubtypic protection after two doses of adjuvanted vaccination were comparable to those of QS-21. T cell immunity played an important role in conferring cross-protection by VSA-1-adjuvanted vaccination. Overall, the findings in this study suggest that VSA-1 exhibits desirable adjuvant properties and a unique pattern of innate and adaptive immune responses, contributing to improved homologous and heterosubtypic protection by inactivated split influenza vaccination in mice.

Universal protection against influenza viruses by multi-subtype neuraminidase and M2 ectodomain virus-like particle

Annual influenza vaccination is recommended to update the variable hemagglutinin antigens. Here, we first designed a virus-like particle (VLP) displaying consensus multi-neuraminidase (NA) subtypes (cN1, cN2, B cNA) and M2 ectodomain (M2e) tandem repeat (m-cNA-M2e VLP). Vaccination of mice with m-cNA-M2e VLP induced broad NA inhibition (NAI), and M2e antibodies as well as interferon-gamma secreting T cell responses. Mice vaccinated with m-cNA-M2e VLP were protected against influenza A (H1N1, H5N1, H3N2, H9N2, H7N9) and influenza B (Yamagata and Victoria lineage) viruses containing substantial antigenic variations. Protective immune contributors include cellular and humoral immunity as well as antibody-dependent cellular cytotoxicity. Furthermore, comparable cross protection by m-cNA-M2e VLP vaccination was induced in aged mice. This study supports a novel strategy of developing a universal vaccine against influenza A and B viruses potentially in both young and aged populations by inducing multi-NA subtype and M2e immunity with a single VLP entity.

A chimeric thermostable M2e and H3 stalk-based universal influenza A virus vaccine

We developed a new chimeric M2e and H3 hemagglutinin (HA) stalk protein vaccine (M2e-H3 stalk) by genetic engineering of modified H3 stalk domain conjugated with conserved M2e epitopes to overcome the drawbacks of low efficacy by monomeric domain-based universal vaccines. M2e-H3 stalk protein expressed and purified from Escherichia coli was thermostable, displaying native-like antigenic epitopes recognized by antisera of different HA subtype proteins and influenza A virus infections. Adjuvanted M2e-H3 stalk vaccination induced M2e and stalk-specific IgG antibodies recognizing viral antigens on virus particles and on the infected cell surface, CD4⁺ and CD8⁺ T-cell responses, and antibody-dependent cytotoxic cell surrogate activity in mice. M2e-H3 stalk was found to confer protection against heterologous and heterosubtypic cross-group subtype viruses (H1N1, H5N1, H9N2, H3N2, H7N9) at similar levels in adult and aged mice. These results provide evidence that M2e-H3 stalk chimeric proteins can be developed as a universal influenza A virus vaccine candidate for young and aged populations.

Universal protection efficacy against influenza viruses by multi-subtype neuraminidase and M2 ectodomain virus-like particle vaccination in young and older adult mice

Annual influenza vaccination is recommended to update the variable hemagglutinin antigens. [add more scientific justification for why NA + M2e immunity will be important?] Here, we first designed a virus-like particle (VLP) displaying consensus multi-neuraminidase (NA) subtypes (cN1, cN2, B cNA) and M2 ectodomain (M2e) tandem repeat (m-cNA-M2e VLP). Vaccination of mice with m-cNA-M2e VLP induced broad NA inhibition (NAI), M2e antibodies as well as interferon-gamma secreting T cell responses. Mice vaccinated with m-cNA-M2e VLP were protected against multi strains of different subtypes (H1N1, H5N1, H3N2, H9N2, H7N9) influenza A viruses containing substantial antigenic variations. From the T cell depletion and passive transfer experiments, we found that immunization of mice with m-cNA-M2e VLP induced cellular and humoral immune components contributing to broader cross protection. Also, surrogate effector assay indicated antibody-dependent cellular cytotoxicity as an additional protective immune contributor. Furthermore, comparable cross protection by m-cNA-M2e VLP vaccination was induced in aged mice. This study supports a novel strategy of developing a universal vaccine against influenza viruses potentially in both young and aged populations by inducing multi-NA subtype and M2e immunity with a single VLP entity.

Supported by grants from NIH/NIAID (AI093772, AI154656, AI147042)

The immunologic effects of different adjuvants on enhancing homologous and cross-protection by influenza virus vaccination in young and aged mice

Seasonal vaccination is ineffective in the elderly population and in conferring cross-protection against antigenically different influenza viruses. Therefore, the cross-protective efficacy of influenza vaccines needs to be improved. Here, we compared the effects of different adjuvants (QS-21+MPL, CpG+MPL, BCG CWS, Saponin VSA-1, Quil-A, and Alum) on enhancing the immunogenicity and homologous and cross-protection by influenza vaccination in mice. QS-21+MPL adjuvant was most effective in inducing Th1 T cell, cross-reactive IgG, and hemagglutination inhibiting antibody responses to vaccination. QS-21+MPL and CpG+MPL adjuvants exhibited high potency by preventing weight loss and reducing viral loads and conferring enhanced homologous and cross-protection in young and aged mice. BCG cell-wall skeleton (CWS) displayed lower adjuvant efficacy in inducing Th1 IgG responses and conferring cross-protection. VSA-1 (an analog of licensed adjuvant QS-21) exhibited adjuvant effects on enhancing the protective efficacy against homologous and heterosubtypic viruses comparable to QS-21. Saponin Quil-A exhibited adjuvant effects in CD4-deficient mice suggesting a CD4-independent adjuvant mechanism, in contrast to CpG that requires intact CD4 T cells. The findings suggest that QS-21+MPL, CpG+MPL, and VSA-1 exhibit desirable adjuvant properties on enhancing cross-protective humoral and cellular immunity to vaccination, with a unique pattern of innate immune responses, contributing to improved homologous and heterosubtypic protection. This study has significance in better understanding the effects of potent adjuvants on enhancing homologous and cross-protection to influenza vaccination in young and older adults.

This study was supported by NIH/NIAID grants AI093772 (S.M.K.), AI154656 (S.M.K), and AI147042 (S.M.K).

Comparison of the effects of different potent adjuvants on enhancing the immunogenicity and cross-protection by influenza virus vaccination in young and aged mice

Vaccination against influenza viruses suffers from low efficacy in conferring homologous and cross-protection, particularly in older adults. Here, we compared the effects of three different adjuvant types (QS-21+MPL, CpG+MPL and bacterial cell wall CWS) on enhancing the immunogenicity and homologous and heterosubtypic protection of influenza vaccination in young adult and aged mouse models. A combination of saponin QS-21 and monophosphoryl lipid A (QS-21+MPL) was most effective in inducing T helper type 1 (Th1) T cell and cross-reactive IgG as well as hemagglutination inhibiting antibody responses to influenza vaccination. Both combination adjuvants (QS-21+MPL and CpG+MPL) exhibited high potency by preventing weight loss and reducing viral loads and enhanced homologous and cross-protection by influenza vaccination in adult and aged mouse models. Bacillus Calmette-Guerin cell-wall skeleton (CWS) displayed substantial adjuvant effects on immune responses to influenza vaccination but lower adjuvant efficacy in inducing Th1 IgG responses, cross-protection in adult mice, and in conferring homologous protection in aged mice. This study has significance in comparing the effects of potent adjuvants on enhancing humoral and cellular immune responses to influenza virus vaccination, inducing homologous and cross-protection in adult and aged populations.

Enhanced cross protection by hetero prime-boost vaccination with recombinant influenza viruses containing chimeric hemagglutinin-M2e epitopes

Annual repeat influenza vaccination raises concerns about protective efficacy against mismatched viruses. We investigated the impact of heterologous prime-boost vaccination on inducing cross protection by designing recombinant influenza viruses with chimeric hemagglutinin (HA) carrying M2 extracellular domains (M2e-HA). Heterologous prime-boost vaccination of C57BL/6 mice with M2e-HA chimeric virus more effectively induced M2e and HA stalk specific IgG antibodies correlating with cross protection than homologous prime-boost vaccination. Induction of M2e and HA stalk specific IgG antibodies was compromised in 1-year old mice, indicating significant aging effects on priming subdominant M2e and HA stalk IgG antibody responses. This study demonstrates that a heterologous prime-boost strategy with recombinant influenza virus expressing extra M2e epitopes provides more effective cross protection than homologous vaccination.

Drug resistance in Candida albicans isolates and related changes in the structural domain of Mdr1 protein

BACKGROUND

The increasing azole drug resistance in fungal pathogens poses a pressing threat to global health care. The coexistence of drug-resistant Candida albicans with tuberculosis patients and the failure of several drugs to treat C. albicans infection extend hospital stay, economic burden, and death. The misuse or abuse of azole-derived antifungals, chronic use of TB drugs, different immune-suppressive drugs, and diseases like HIV, COVID-19, etc., have aggravated the situation. So it is vital to understand the molecular changes in drug-resistant genes to modify the treatment to design an alternative mechanism.

METHOD

C. albicans isolated from chronic tuberculosis patients were screened for antifungal sensitivity studies using disk diffusion assay. The multidrug-resistant C. albicans were further screened for molecular-level changes in drug resistance using MDR1 gene sequencing and compared with Gen bank data of similar species using the BLAST tool.

RESULTS

The investigation proved that the isolated C. albicans from TB patients are significantly resistant to the action of six drugs. The molecular changes in MDR1 genes showed differences in seven nucleotide base pairs that interfered with the efflux pump.

Dry Aging of High Ultimate pH Beef

ObjectivesDry aging is a process in which water is removed from the meat by evaporation. As meat loses water, the flavor compounds are concentrated, resulting in stronger flavor. Meat pH may be important when dry aging as it relates to the ability of muscle to bind water. Therefore, this study aimed to evaluate pH effects on water loss when dry aging and the effects on meat quality characteristics. Dry aging of dark cutting (DC) beef may improve flavor and increase yield.Materials and MethodsSix USDA low Choice and six dark cutting (DC) carcasses with the same degree of marbling were selected and boneless strip loins from both sides were obtained. Longissimus muscle pH was measured, and carcasses were classified as DC (pH = 6.69), or control (pH = 5.47). Then, strip loins from each animal were assigned to 2 aging methods (wet or dry). The 4 treatments included 2 dry aging (DRY and DRY-DC) and 2 wet-aging treatments (WET and WET-DC). Dry aging occurred in individual dry-aging chambers at 50% relative humidity and 2200 RPM fan speed. The chambers (86 cm Length × 48 cm Width × 35 cm Height) have built-in weighing scales that can continuously monitor weight loss (± 5 g). Wet and dry-aged loins were aged in the same cooler for 45 d at 1°C.After aging, loins were fabricated into steaks and evaluated for trim loss, yield, tenderness (WBSF), color, discoloration, lipid oxidation, and sensory analysis (flavor) via triangle test (n = 32). Steaks assigned for color and lipid oxidation were placed under retail display (RD) at 2°C for 7 d. Rate of moisture loss and color data were analyzed as a split plot design with repeated measures. The TBARS data were analyzed as a split-plot design. All the other data were analyzed as a completely randomized design. Chamber (loin) was considered the experimental unit. Data were analyzed using the PROC GLIMMIX procedure of SAS with α = 0.05.ResultsWet-aged treatments had lower moisture loss, trim loss and higher yield than dry-aged treatments (P < 0.05). However, no differences in rate of moisture loss (P = 0.51), total moisture loss (P = 0.96), trim loss (P = 0.69), or yield (P = 0.75) between DRY-DC and DRY were found. There were no differences among treatments for WBSF (P = 0.67). In general, DRY-DC and WET-DC steaks had the lowest lightness (L*) values, redness (a*) values (Fig. 3a), and yellowness (b*) values over the first 5 d of RD (P < 0.05). Discoloration scores for DC steaks remained low throughout the RD period (Fig. 3b). DRY steaks had greater TBARS values than any other treatment at 0 d RD. At 4 and 7 d of RD, DRY-DC and WET-DC steaks had the lowest TBARS values, DRY steaks had the highest, while WET was intermediate (P < 0.001). Results from the triangle test indicated a detectable difference between DRY-DC versus DRY (P = 0.01), DRY-DC versus WET-DC (P = 0.01), DRY-DC versus WET (P = 0.01), and WET-DC versus WET (P < 0.01). Panelists frequently made unsolicited comments which suggested inferior eating satisfaction associated with DC flavor (wet or dry), although they were not asked questions regarding preference.ConclusionUltimate pH did not affect the rate and total moisture loss in dry aged beef. Results suggest that neither yield nor flavor were positively affected by dry aging of DC beef.Figure 3.a) Effect of ultimate pH (Dark cutters [DC] vs. Normal) and aging method (Wet vs. Dry) on objective redness (a*) values of strip loins steaks aged for 45 d through 7 d of retail display. b) Effect of ultimate pH (Dark cutters [DC] vs. Normal) and aging method (Wet vs. Dry) on discoloration (%) of strip loins steaks aged for 45 d through 7 d of retail display. a-c Means within a day with different superscripts are different (P < 0.005).

Color and Lipid Stability of Dry Aged Beef During Retail Display

ObjectivesThere has been an increased interest in merchandising dry-aged steaks at the retail level. Further understanding of the influence of the dry aging process on meat color and lipid stability is needed to ensure dry-aged beef products can be merchandised without adverse impacts on retail display life. Therefore, this study aimed to determine color and lipid stability of steaks from dry-aged beef loins over 7 d (d) of retail display.Materials and MethodsSixteen USDA low Choice boneless strip loins were assigned to one of four aging treatments: vacuum (Wet), dry-aging at 50% relative humidity (RH) (RH50), dry-aging at 70% RH (RH70), or dry-aging at 85% RH (RH85). Dry-aged loins were placed in each assigned dry aging chamber, while wet aged counterparts were aged in vacuum bags in the same cooler. Loins were aged for 42 d at 1°C. After aging, loins were trimmed of dehydrated lean/fat and fabricated into steaks. Steaks were trimmed of subcutaneous fat, and placed on foam trays, overwrapped with oxygen permeable film and placed under retail display (RD) conditions for 7 d at 2°C. Objective color measurements were taken once daily from d 0 to 7 of RD. Trained visual color panelists (n = 6) evaluated surface discoloration from d 0 to 7 of RD once daily. Lipid oxidation was measured via thiobarbituric acid reactive substance assay (TBARS) at 0, 4, and 7 d of RD. Color data were analyzed as a split-plot repeated measures design with treatment as the whole-plot and RD time as the repeated measures. TBARS data were analyzed as a split-plot design with aging treatment as the whole-plot, and RD time as the split-plot. In this study, chamber (loin) was considered the experimental unit. Data were analyzed using the PROC GLIMMIX procedure of SAS with α = 0.05.ResultsFor all three-color scales, a RD effect was found (P < 0.001). In general, L*, a* and b* values decreased as RD time increased, regardless of the aging treatment. Wet-aged steaks had higher L* (P < 0.05), a* (P < 0.05), and b* values (P < 0.001) than any other dry-aged treatment. No differences in L*, a*, and b* values among dry aging treatments were found (P < 0.05). A 2-way interaction between treatment and RD for discoloration was observed (P < 0.05). No differences were found among treatments over the first 2 d of RD (P > 0.05). Samples began to diverge on Day 3 of RD. Dry-aged steaks had greater discoloration scores (P < 0.05) than wet-aged steaks at 4, 5, 6, and 7 d of RD. However, no differences in discoloration scores among RH treatments were found. There was a RD effect on TBARS values (P < 0.001). Greater TBARS values were found as RD progressed from d 0 to d 4 and d 7, regardless of the aging treatment. A treatment effect was observed for lipid oxidation (P < 0.05). Dry-aged steaks had higher TBARS values than wet-aged steaks. No differences in TBARS values among dry aging treatments were found.ConclusionDry aging of beef resulted in decreased lightness and redness values and increased lipid oxidation compared to wet aging. Results suggest that with prolonged RD dry aging of beef has the potential to reduce color and lipid stability compared to wet-aging and thus reduce display life. Dry-aged steaks met the 20% discoloration threshold and overcame the acceptability threshold of 2.28 mg of malonaldehyde/kg at d 4 of RD, indicating that dry-aged steaks can be merchandised in the retail level for 3 d without detrimental effects on color and lipid oxidation.

Relationship Between Relative Humidity and Moisture Loss in Dry Aged Beef

ObjectivesThe objective of this research was to assess the impact of low relative humidity (RH) during dry aging on moisture and trim loss, tenderness, and flavor. The working hypothesis was that rapid drying would create a hard crust on the meat surface that could reduce moisture release over time, thereby reducing weight loss, enhancing tenderness (by retaining more water), and altering flavor when compared to dry aging at higher RH.Materials and MethodsSixteen USDA low Choice boneless strip loins were assigned to one of the four aging treatments: vacuum (Wet), dry-aging at 50% RH (RH50), dry-aging at 70% RH (RH70), or dry-aging at 85% RH (RH85). Loins were placed in individual dry aging chambers and aged for 42 d at 1°C and 2200 RPM fan speed. A computerized dry aging system was designed and built that is capable of measuring and precisely controlling RH (± 1%), temperature (± 0.5°C), and air velocity (± 0.1m/s). The chambers have built-in weighing scales that can continuously monitor weight loss (± 5 g). All measured data can be saved on the connected computer in intervals of 1 s. After aging, loins were trimmed of dehydrated fat/lean and evaluated for trim loss. Loins were fabricated anterior to posterior, cut into steaks and evaluated for water activity (aw), Warner-Bratzler shear force (WBSF), and by sensory analysis to detect flavor differences via triangle test (n = 32). Rate of moisture loss was analyzed as a split plot design with treatment as the main plot and days of aging as the repeated measures. All the other data were analyzed as a completely randomized design. Chamber (loin) was considered the experimental unit. Data were analyzed using the PROC GLIMMIX procedure of SAS with α = 0.05.ResultsThere was a treatment by day interaction for rate of moisture loss (P < 0.001). A faster rate of moisture loss was found for RH50 when compared to RH85 on the first day of aging (P < 0.001), while RH70 was intermediate. Loins dry-aged at RH50 and RH70 had higher rates of moisture loss than RH85 on Days 2 and 3 of aging (P < 0.05). By Day 4, no differences in rate of moisture loss among RH treatments were found (P > 0.05). Wet-aged samples had lower moisture loss (P < 0.001), trim loss (P < 0.001) and higher yield (P < 0.001) than all dry-aged treatments. However, there were no differences among RH treatments for total moisture loss (P > 0.05), trim loss (P > 0.05) and yield (P > 0.05). Steaks from dry-aging treatments had lower aw values (P < 0.001) than steaks from the Wet group. No differences in aw values among RH treatments were found (P > 0.05). There was a location effect for aw values. Samples from the ventral region of the steak had lower aw values than samples from the central and dorsal region (P < 0.001). There were no differences among treatments for WBSF (P > 0.05). Results from the triangle test indicated that there was a detectable difference between Wet and RH70 (P < 0.05). However, there was no detectable difference between RH50 and RH85 (P > 0.05).ConclusionResults suggest that no such case hardening effect occurs when dry aging beef, even when the RH was kept very low (50%) and the total weight loss was 23%. Instead, the lower RH results in more rapid moisture loss at the beginning of the aging process without significantly affecting the total amount of moisture loss. Trim loss, yield, tenderness and flavor were not affected by relative humidity during dry aging.

Application of a dry heat treatment to enhance the functionality of low-heat nonfat dry milk

Nonfat dry milk is a valuable food and ingredient because it contains proteins, fat, carbohydrates, minerals, and vitamins. When manufactured, this product is classified into high heat (HH) or low heat (LH) depending on the pre-heat treatment used in pasteurization. Radio frequency dielectric heating, if used alone or as part of a dry heat technology, may induce component interactions in milk powders, which could alter or improve functionality. To pursue this objective, LH was subjected to radio frequency dielectric heating to 80, 85, and 90°C with a subsequent hold period of 60 or 90 min in an oven, set at the designated temperature, 80, 85, or 90°C, assessed for functionality in liquid and gel systems, cooled, and subsequently compared with LH and HH. The functionality assessment included heat stability and foaming, emulsion, and gelling properties. For foaming, LH presented a statistically lower overrun and foam stability compared with all dry-heated LH. The LH dry-heated at ≥85°C exhibited significantly greater foaming capacity than did the LH. Emulsification properties were not significantly different as a function of dry heating compared with LH. As gels, water-holding capacity was greater and syneresis was significantly less for all gels made with the dry-heated LH at <85°C. Gel firmness and cohesiveness were not affected by dry heating. The heat coagulation time at native pH was significantly greater for LH that were dry-heated for 90 min compared with LH. At adjusted pH (6.4 to 7.2), the heat stability was improved if the LH was dry-heated. The dry-heated LH had significantly less foaming properties, but greater emulsion activity compared with the HH. Overall, the dry heat treatment conditions of this study did not result in acid-induced gels with equivalent properties as gels made with HH. Syneresis was similar for all gels except for those made from the dry-heated LH to 90°C and held for 60 min, as this gel had significantly more syneresis than did the gels made from HH. However, the heat stability of dry-heated LH at native, 6.8, 7.0, and 7.2 pH was greater compared with the heat stability of HH. The application of a dry heat treatment enhanced the functional properties of LH, opening the opportunity to develop food products that can use this modified nonfat dry milk such as ice cream, bakery, and meat products.

Determination of yolk contamination in liquid egg white using Raman spectroscopy

Purified egg white is an important ingredient in a number of baked and confectionary foods because of its foaming properties. However, yolk contamination in amounts as low as 0.01% can impede the foaming ability of egg white. In this study, we used Raman spectroscopy to evaluate the hypothesis that yolk contamination in egg white could be detected based on its molecular optical properties. Yolk contaminated egg white samples (n = 115) with contamination levels ranging from 0% to 0.25% (on weight basis) were prepared. The samples were excited with a 785 nm laser and Raman spectra from 250 to 3,200 cm(-1) were recorded. The Raman spectra were baseline corrected using an optimized piecewise cubic interpolation on each spectrum and then normalized with a standard normal variate transformation. Samples were randomly divided into calibration (n = 77) and validation (n = 38) data sets. A partial least squares regression (PLSR) model was developed to predict yolk contamination levels, based on the Raman spectral fingerprint. Raman spectral peaks, in the spectral region of 1,080 and 1,666 cm(-1), had the largest influence on detecting yolk contamination in egg white. The PLSR model was able to correctly predict yolk contamination levels with an R(2) = 0.90 in the validation data set. These results demonstrate the capability of Raman spectroscopy for detection of yolk contamination at very low levels in egg white and present a strong case for development of an on-line system to be deployed in egg processing plants.

Spontaneous and coherent anti-Stokes Raman spectroscopy of human gastrocnemius muscle biopsies in CH-stretching region for discrimination of peripheral artery disease

Peripheral Artery Disease (PAD) is a common manifestation of atherosclerosis, characterized by lower leg ischemia and myopathy in association with leg dysfunction. In the present study, Spontaneous and coherent anti-Stokes Raman scattering (CARS) spectroscopic techniques in CH-stretching spectral region were evaluated for discriminating healthy and diseased tissues of human gastrocnemius biopsies of control and PAD patients. Since Raman signatures of the tissues in the fingerprint region are highly complex and CH containing moieties are dense, CH-stretching limited spectral range was used to classify the diseased tissues. A total of 181 Raman spectra from 9 patients and 122 CARS spectra from 12 patients were acquired. Due to the high dimensionality of the data in Raman and CARS measurements, principal component analysis (PCA) was first performed to reduce the dimensionality of the data (6 and 9 principal scores for Raman and CARS, respectively) in the CH-stretching region, followed by a discriminant function analysis (DFA) to classify the samples into different categories based on disease severity. The CH2 and CH3 vibrational signatures were observed in the Raman and CARS spectroscopy. Raman and CARS data in conjunction with PCA-DFA analysis were capable of differentiating healthy and PAD gastrocnemius with an accuracy of 85.6% and 78.7%, respectively.

Predicting beef tenderness using near-infrared spectroscopy1

The objective of this multiple-phase study was to determine the accuracy of an on-line near-infrared (NIR) spectral reflectance system to predict 14-d-aged cooked beef tenderness. In phase I, 292 carcasses (140 US Select, 152 US Choice) were selected (d 2) from 2 commercial beef processing facilities. After carcass selection, longissimus lumborum (LL) muscle sections (ribs 9 to 12) were individually identified, vacuum-packaged, and transported to the Oklahoma State University Meats Laboratory, where a 2.54-cm-thick steak (n = 1) was fabricated and stored in refrigerated conditions (1 degrees C +/- 1). Following a 30-min oxygenation period, a NIR spectral scan was obtained on the 12th-rib LL steak. Steaks (d 3) were individually vacuum-packaged and aged at 4 degrees C for a total of 14 d before cooking slice shear force (SSF) analysis. In phases II and III, 476 carcasses (258 US Select, 218 US Choice) were immediately NIR scanned after carcass presentation to in-plant USDA grading personnel. In a similar fashion, all LL steaks were aged (1 degrees C +/- 1) for 14 d before cooking (70 degrees C) and conducting SSF. Of the phase I and II samples, 39 (6.77%) were categorized as being tough (i.e., >/= 25 kg of SSF after the 14-d postmortem aging period). Of these 39 tough samples, 20 (3.7% error rate) were correctly placed in the 90% certification level. Another 10 tough samples were placed in the 80% certification level (2.0% error rate). The overall NIR certified tender group was 1.67 kg more tender (P < 0.05) than LL samples from the noncertified samples. When the NIR predicted samples to be tough, 10% of the samples were eliminated from the phase I and II LL populations at 90% certification. The population SSF mean improved in excess of 6.5 kg. For phase III, SSF evaluation by an independent third party indicated the NIR system was able to successfully sort tough from tender LL samples to 70% certification levels. It was concluded that NIR scanning offers an in-plant opportunity to sort carcasses into tenderness outcome groups for guaranteed-tender branded beef programs.