Comparison of volumetric and surface decontamination techniques for innovative processing of mealworm larvae (Tenebrio molitor)

For food and feed safety of edible insects, effective decontamination methods need to be evaluated and developed. Traditional decontamination and preparation methods were reviewed and thermal and innovative inactivation methods for the decontamination of mealworm larvae were evaluated and compared. The impact of the surface decontamination techniques direct and indirect plasma treatment, and of volumetric methods such as high hydrostatic pressure treatment (400, 500, and 600 MPa) and thermal treatments (45 °C and 90 °C) for up to 15 min on the surface microbial load and on the overall microbial count of mealworm larvae (Tenebrio molitor) have been investigated. It was found that the indirect plasma treatment was an effective means for the surface decontamination of mealworm larvae, whereas high hydrostatic pressure at 600 MPa and thermal treatments in a water bath at 90 °C in comparison resulted in the highest reduction of the overall count. It is thus concluded that volumetric methods are favorable for the inactivation of the gut microbiota of insects.Industrial relevanceEdible insects represent a valuable alternative protein source that could contribute to food and feed security and are industrially mainly unexploited. For a successful marketing of edible insects food and feed safety has to be ensured and effective decontamination methods need to be developed.     

The influence of product preparation,familiarity and individual traits on the consumer acceptance of insects as food

Insects are highly valued as food in many cultures but have only recently gained interest in the West as a sustainable alternative to reduce the environmental impact of meat production. Despite the growing consumer interest in insect consumption, there is still a great disparity between curious trying and actual acceptance. The aim of this study was to examine how the product preparation, familiarity and individual traits (e.g. food neophobia) influence the consumer acceptance of insects as food. Dutch consumers (n = 976) evaluated 8 mealworm product images on 4 acceptability measures (product appropriateness, expected sensory-liking, willingness to buy, willingness to try). Product images varied according to mealworm visibility (visible/invisible), carrier flavour (savoury/sweet) and carrier origin (Western/Asian). High product acceptability was not simply achieved by adding mealworms to familiar foods. Acceptability depended very much on the perceived appropriateness of mealworms as food and the perceived appropriateness of the product combination. However, mealworm products were always expected to be inferior to the carrier products, even when visually identical. Familiarity with mealworms and individual traits played a relatively minor role, and influenced the willingness to try more than the other acceptability measures. We conclude that appropriate product design is important but insufficient to achieve consumer acceptance of insects as food in the West. Additional incentives are required to encourage acceptance beyond the mere willingness to try. We discuss the complexities underlying the consumer acceptance of insects as food and reflect on how acceptance might be increased in the future.     

Cold atmospheric pressure plasma processing of insect flour from Tenebrio molitor: Impact on microbial load and quality attributes in comparison to dry heat treatment

In this study, the applicability of semi-direct cold atmospheric pressure plasma (CAPP) during postharvest processing of Tenebrio molitor flour is investigated. Besides analyzing the decontamination efficacy, plasma-induced impact on techno-functionality, protein solubility, composition and structure was determined and compared to heat induced effects.Following CAPP treatment, the total microbial load of the Tenebrio flour of 7.72 log₁₀ cfu/g was reduced to 7.10 (1 min), 6.72 (2.5 min), 5.79 (5 min), 5.19 (7.5 min), 5.21 (10 min) and 4.73 (15 min) log₁₀ cfu/g. With increasing exposure to CAPP, protein solubility at pH 4 almost linearly decreased to a minimum of 54%. Water binding capacity decreased from 0.79 to 0.64 g_water/g whereas oil binding capacity increased from 0.59 to 0.66 g_oil/g. Gel electrophoresis revealed a decrease of all protein fractions at pH 4 whereas at pH 10 the band pattern significantly shifted to protein fractions with higher molecular weights.Industrial relevanceEdible insects are rich in valuable protein, fat, fibre, minerals and micronutrients. Although a wide range of species represent a valuable alternative protein source that could contribute to food and feed security, they are industrially hardly exploited. The tailored application of proper processing technologies could lead to novel insect-based high-protein food and feed products with unique functional properties supporting the increase in acceptability among potential consumers. Current research concentrates on developing processing chains including innovative nonthermal approaches. Cold atmospheric pressure plasma (CAPP) has gained attention as an effective technology for the decontamination and modification of fresh and dry agricultural products. In the postharvest chain of edible insects, the application of CAPP could contribute to the development of safe and high-quality insect-based products in the food and feed sector.     

The growth and survival of Escherichia coli O157:H7 on minced bison and pieces of bison meat stored at 5 and 10 °C

This study investigated the growth and survival of Escherichia coli O157:H7 on minced and whole pieces of bison meat. Growth curves of native microflora, including Pseudomonas spp. and Enterobacteriaceae were also generated. A marked E. coli O157:H7 strain was inoculated onto minced and whole pieces of bison meat at an initial level of 1.5 log₁₀ cfu g⁻¹. The inoculated meat was stored at either 5 °C for 28 days or 10 °C for 21 days. Survival, but no growth, of E. coli O157:H7 was observed on both forms of bison meat stored at 5 °C, while significant growth of the organism was observed at 10 °C. E. coli O157:H7 counts on whole pieces were generally higher than counts observed on minced bison meat, and reached their highest population by 14 days, with a total increase of 3.36 log₁₀ cfu g⁻¹ on whole pieces and 2.12 log₁₀ cfu g⁻¹on minced bison meat stored at 10 °C. Under the same storage temperature, Pseudomonas spp. and total counts displayed similar growth patterns on both pieces and minced bison meat, while the Enterobacteriaceae showed a slower growth rate. This study showed that the growth of E. coli O157:H7 on bison meat is similar to that observed in studies of beef.     

Effect of high pressure processing on physicochemical and microbiological properties of marinated beef with reduced sodium content

High pressure processing (HPP) is one of the newer technologies that has shown great potential for manufacturing meat products with reduced sodium content. The aim of this study was to evaluate the effect of HPP applied at different levels in the inactivation of Listeria innocua and Enterococcus faecium inoculated in marinated beef (Longissimus lumborum) with reduced sodium content, as well as its influence on the physicochemical properties of the meat. Samples were inoculated with 10⁶ CFU/g of L. innocua and E. faecium, and marinated with solutions in different concentrations of NaCl (1 or 2%) and citric acid (1 or 2%) for 18 h and treated with high pressure (300, 450 or 600 MPa). Samples treated with 600 MPa were also evaluated regarding physicochemical stability after 14 days of refrigerated storage. Different marinating solutions were not sufficient to reduce initial microbial loads in the non-pressurized samples, but the combination with high pressure caused six log cycle reductions of both microorganisms. The treatment with 2% salt/2% citric acid was the most effective for each pressure considered for both bacteria. No significant changes were observed in the water activity of the samples, however samples with higher concentration of citric acid showed lower (p < 0.05) pH and lower (p < 0.05) lipid oxidation after 14 days of storage under refrigeration. Only samples treated with 600 MPa showed an increase (p < 0.05) in hardness. The results showed that HPP was able to process a safe meat product with reduced sodium concentration.Industrial relevanceThe result from this study shows the benefits of using HPP as an alternative meat processing technology to develop a meat product with reduce sodium content. Meat processed by this method have better nutritional quality and extended shelf life as compared to conventional processing. The step taken in this study will aid the meat processing industry for the development of microbiologically safe meat product with low sodium content by the application of high pressure processing.     

Mechanical separation process for the value enhancement of Atlantic horse mackerel (Trachurus trachurus), a discard fish

Mechanically separated meat (MSM) is the product obtained by removing meat from bones by pressure application. Whole fillets and fish burgers from minced muscle and from mechanical separation of Atlantic horse mackerel (Trachurus trachurus) were evaluated immediately after processing (T₀) and after 90 days of storage at − 20 °C for parameters related to quality loss. Firstly, mechanical separation inhibited water losses (2.67% against 4.57 and 5.57% in whole fillets and burgers from minced muscle, respectively), but the colour of MSM was duller and redder than the samples from other groups. Horse mackerel contained low fat (< 1 g/100 g muscle), and high PUFAω3 content (around 57 g/100 g total fatty acids), especially EPA and DHA (around 52 g/100 g) regardless the treatment. However, the species was susceptible to oxidation, as revealed by the high TBARS content at T₀ (> 8 mg MDA-eq/100 g muscle). Nevertheless, Atlantic horse mackerel showed a high antioxidant capacity (ABTS, 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid, DPPH, 2,2-diphenyl-1-picrylhydrazyl, and FRAP, ferric-reducing ability) at T₀ which may protect muscle against oxidative damages both during processing treatment and storage.Industrial relevanceThe mechanical separation process described in the article has been largely utilized for terrestrial animal products. However, it is seldom adopted by fish industry, especially for recovering discard fish species. Horse mackerel is an underutilized species, normally transformed into animal feed despite its high levels of omega-3 polyunsaturated fatty acids. Therefore this study was conducted in order to determine the effect of a mechanical separation technique on the physicochemical properties of horse mackerel. Our study showed that, although this species is susceptible to oxidative changes, mechanically separate meat can be a high-quality ingredient in burgers, nuggets, sticks, or even sauces which may represent a way for the valorisation of discard species.     

Fermented minced pepper by high pressure processing,high pressure processing with mild temperature and thermal pasteurization

High pressure processing (HPP) and thermal pasteurization (TP) of fermented minced pepper (FMP) were comparatively evaluated by examining their impacts on microbial load, titratable acid (TA), pH, a_w, firmness, color, capsanthin, ascorbic acid (AA), and biogenic amines (BAs) after processing and during 12 weeks of storage at 25 and 37 °C. The total plate count (TPC) in FMP samples was reduced by 1.48, 0.12 and 1.58 log₁₀ CFU/g after TP (83 °C/15 min), HPP1 (500 MPa/20 °C/5 min) and HPP2 (500 MPa/50 °C/5 min), respectively. The population of spores was reduced by 1.21 log₁₀ CFU/g only after HPP2. During storage at 25 or 37 °C, the TPC in TP, HPP1, and HPP2 samples increased by 0.88/1.21, 0.41/0.62 and 0.60/0.86 log₁₀ CFU/g, respectively, while the spores decreased below the detection limit. The retention of firmness after TP, HPP1 and HPP2 was 36.91, 91.15 and 66.48% respectively, and HPP-treated samples exhibited more retention during the storage. Color of FMP samples was not changed by TP, but slightly changed by HPP1 and HPP2. The content of capsanthin retained 78.99, 93.71 and 88.19% after TP, HPP1 and HPP2, it showed a small decrease during storage. Levels of biogenic amines (BAs) in HPP2 samples were lower than that of TP and HPP1 ones. There were better sensory quality and lower microbial level in HPP-treated samples during storage, indicating that HPP is a better choice for the preservation of FMP.Industrial relevanceConsumption of fermented minced pepper (FMP), as a traditional Chinese food, is becoming increasingly popular. Considering that heat treatment may destroy some heat-sensitive quality of the products, this study evaluated the effects of high pressure processing (HPP) on quality of FMP. Findings of this study could help processors commercialize HPP to replace current thermal processing in industrial production.     

Optimization of radiation dose and quality parameters for development of ready-to-cook (RTC) pumpkin cubes using a statistical approach

Full factorial design was employed to study the effect of gamma irradiation (0–2.5 kGy) and storage (up to 28 d) at 10 °C on quality of RTC pumpkin. Data obtained from microbial, color, texture and sensory analysis were fitted into a cubic model. Resulting equations were solved to assess radiation dose and maximum storage period for acceptable microbial quality (< 10⁵ CFU g^− 1) and sensory scores (overall acceptability > 5). Radiation dose of 1 kGy resulted in a product with desired microbial and sensory quality up to storage period of 21 d. The processed product (1 kGy) had significantly (p < 0.05) higher total antioxidant and vitamin C content as compared to non-irradiated control after storage of 21 d. HPLC analysis demonstrated that there were no qualitative changes in phenolic and carotenoid constituents due to radiation processing. Thus radiation processing was successfully employed to develop RTC pumpkin with improved shelf-life.Industrial relevanceThe present study demonstrates the efficacy of the statistical approach of the experimental design for optimization of radiation dose and storage time for ready-to-cook (RTC) pumpkin cubes with acceptable microbial and sensory quality. Complex interactions among radiation dose, storage duration and quality attributes of RTC pumpkin were successfully mathematically modeled. The mathematical modeling can be useful for commercial production as the required processing conditions can be suitably obtained based on the desired quality characteristics of the final product.     

Salt-stressed fresh cut leek accelerates CO2 and C2H4 production and enhances the development of quality characteristics of traditional Greek sausages during storage

Fresh cut leek was mixed with salt for 0.5 (IM) and 5 (LM) min or remained untreated (control) and stored alone or mixed with minced meat and seasonings, cased and stored at 15 °C for 7 days. The fresh cut leek and sausage metabolics and sausage microbiological and physicochemical traits were measured during storage. Sausages with LM leek had significantly higher counts of lactic acid bacteria, faster rates of pH drop and dehydration and increased red color compared with the other treatments. Sausage to fresh cut leek peaks of CO₂ or C₂H₄ production was 5 or 2 fold higher in LM than the other treatments indicating that the sausage flora was the source of both. The use of salt-stressed fresh cut leek before manufacture of sausages enhances microbial activity as well as its stability and shortens the necessary storage time needed for the development of the quality characteristics of Greek traditional sausages.     

Shelf life of cooked goat blood sausage prepared with the addition of heart and kidney

This study focused on the effect of two packaging formats (vacuum packaging and over-wrap packaging) on the shelf life of cooked sausage prepared with blood, heart, kidney and goat meat fragments under storage at 4 ± 1 °C for a period of 90 days. The storage time and type of packaging significantly affected the chemical (pH, moisture, protein and TBARS number), physical (shear force) and microbial (mould and yeast) parameters of cooked sausage. Vacuum packaging maintained the microbiological and chemical qualities of cooked goat blood sausage for a longer period of time (63 days) compared to over-wrap packaging (41 days) and could be a viable alternative to refrigerated storage of the product for quality maintenance.     

Total Phosphorus Content in Technologically Unprocessed Meat

The total phosphorus content was measured in raw, technologically unprocessed meats. Our results show that total phosphorus content in different raw meats varies substantially (from 1.41 g/kg to 4.22 ± 0.93 g/kg). Based on the results, manufacturers of meat products are advised that before production of any meat product, the precise amount of total phosphorus in raw meat starting material has to be known. Based on this, the content of added synthetic phosphates and polyphosphates together with the content of natural phosphorus in the meat would be within the prescribed values stated in the Regulation, which are 8 g/kg.     

High pressure carbon dioxide combined with high power ultrasound processing of dry cured ham spiked with Listeria monocytogenes

Traditionally, thermal treatments for the inactivation of Listeria monocytogenes in meat products involve undesirable changes of the product quality. In recent years, efforts have been carried out to develop alternative methods to inactivate L. monocytogenes without affecting the product quality attributes. In this context, the feasibility of combined high pressure carbon dioxide and high power ultrasound (HPCO₂ + HPU) treatment to inactivate L. monocytogenes inoculated on the surface of dry cured ham was investigated. Inactivation data were determined at 6, 8 and 12 MPa, as a function of temperature (22, 35, 45 °C) and treatment time (0.5 to 30 min), and compared to those obtained after thermal and HPCO₂ treatments.Color, pH and acidity changes of the samples after both thermal and HPCO₂ + HPU treatments were measured and compared, sensorial profile of the treated samples was evaluated by a sensory panel and shelf-life was determined by a storage study for 4 weeks at 4 °C.The results clearly revealed that HPU alone was not able to induce any microbial inactivation while HPCO₂ + HPU treatment always assured a certain level of inactivation, variable with the process temperature used: the inactivation efficiency was demonstrated higher at 35 °C rather than 22 °C and no enhancement was observed at 45 °C compared to 35 °C. Process conditions of 12 MPa, 35 °C, at 10 W for 5 min assured inactivation to undetectable level of L. monocytogenes spiked on the surface of the product with an initial concentration of about 10⁹ CFU/g. No differences were detected between acidity, pH, color and sensory attributes of the untreated and HPCO₂ + HPU treated dry cured ham surface, while slight differences were measured between the values obtained for the untreated and thermally treated samples. Additionally, the storage study demonstrated that a full microbial and quality shelf-life was assured for 4 weeks at 4 °C. The results obtained may open the doors to the application of such an innovative process at industrial level, in particular to treat ham-type or meat products.     

Combined use of modified atmosphere packaging and high pressure to extend the shelf-life of raw poultry sausage

The contribution of modified atmosphere packaging (MAP) in extending the shelf-life of high-pressure treated raw poultry sausages was examined by considering microbial and oxidative stability (TBARs) aspects. Raw poultry sausages packaged under air or modified atmosphere (50% CO₂–50% N₂) were pressurized at 500 MPa during 5 min at a maximum temperature of 10.5 °C, subsequently allowed to refrigerated storage during 22 days. During storage, samples were tested at time intervals for headspace gas composition, pH, TBARs, Aerobic Mesophilic Counts (AMC) and Lactic Acid Bacteria (LAB) counts. The high pressure treatment could represent an efficient means of extending the microbiological shelf-life, insofar as it reduced and stabilized the AMC and LAB counts. However, the MAP did not further improve the microbial quality. But, still, by limiting lipid oxidation, it remains an essential technology for the control of the organoleptic quality, another important characteristic to consider in shelf-life determinations.Industrial relevanceRaw poultry meat and especially raw ground poultry meat, such as raw poultry sausages are highly perishable.Economic challenges and busier lifestyles have consumers seeking out products with longer and longer shelf-lives. Manufacturers have to respond to this demand by improving processes. The use of alternative preservation techniques such as high hydrostatic pressure represents a promising strategy to enhance the shelf-life of meat products and is preferred by consumers to addition of food additives. Modified atmosphere packaging is largely used to extend the shelf-life of processed meat products. Manufacturers may question the relevance of maintaining MAP while introducing a new step of high pressure treatment in their process. This study showed that MAP significantly reduced lipid oxidation. In that way, MAP remains necessary to maintain organoleptic quality of pressurized raw poultry sausages.     

Extending shelf-life of minimally processed apples with edible coatings and antibrowning agents

Effect of edible coatings in combination with antibrowning agents on minimally processed apple slices was studied during storage at 3°C for 2 week. To control initial respiration rate of apple slices, edible coatings were applied to cut apples as semipermeable barriers against air. Initial respiration rate showed a decrease by 5% and 20% in carrageenan (0.5 g/100 mL)-coated and whey protein concentrate (5 g/100 mL)-coated apples, respectively, at 25°C. Edible coatings in combination with antibrowning agents effectively prolonged the shelf-life of minimally processed apple slices by 2 week when stored in packed trays at 3°C. Addition of various antibrowning agents to these coating solutions was advantageous in maintaining color during storage. Addition of CaCl₂ (1 g/100 mL) significantly inhibited the loss of firmness. These edible coatings in combination with antibrowning agents also showed positive sensory analysis results and beneficial reduction of microbial levels. WPC (5 g/100 mL) containing ascorbic acid (1 g/100 mL) plus CaCl₂ (1 g/100 mL) was the most effective preservation treatment in terms of sensory quality after 2 week.     

Post-thawing quality changes of common carp (Cyprinus carpio) cubes treated by high voltage electrostatic field (HVEF) during chilled storage

In recent years, high voltage electrostatic field (HVEF) technology has been demonstrated to be a viable alternative to high-temperature treatments in processing for inhibiting microbial growth and maintaining post-thawing quality of foods. In this study, common carp (Cyprinus carpio) meat cubes were treated with HVEF, and compared to air-thawed and running tap water-thawed controls to investigate how HVEF affects common carp meat quality after thawing and low-temperature storage (4 °C). The results showed that thawing under − 6, − 12 kV HVEF and running tap water significantly decreased the thawing time by 30, 50 and 45 min, respectively, compared to air thawing control. In addition, − 12 kV HVEF treatment also reduced the moisture loss, which the initial drip loss of it was lower by 2.95% than CK. The initial total viable counts, Aeromonas, Pseudomonas, and lactic acid bacteria were 3.58, 3.15 2.88 and 3.25 log CFU/g in CK after thawing, respectively, which were higher than that in the cube thawed by − 12 kV HVEF (3.11, 2.93 2.71 and 2.91 log CFU/g). Additionally, − 12 kV HVEF treatment enhanced adenosine monophosphate deaminase (AMP-deaminase) activity, reduced acid phosphatase (ACP) activity and delayed the degradation of inosine monophosphate (IMP) to hypoxanthine (Hx). These results suggested that HVEF treatment could be useful in the thawing and storage of frozen common carp fish.Industrial relevanceThe study investigated the effects of high voltage electrostatic field (HVEF) thawing on the water-holding capacity, adenosine triphosphate degradation and microbial community changes of frozen common carp (Cyprinus carpio) cubes when stored at 4 °C. HVEF under − 12 kV was found to have positive influence on reducing the thawing time, maintaining water-holding capacity, decreasing the level of microbe, and delaying adenosine triphosphate (ATP) degradation. A potential application for HVEF in the thawing and storage of frozen aquatic product was highlighted in food industry.     

Enterobacteriaceae in beef products from retail outlets in the Republic of Ireland and comparison of the presence and counts of E. coli O157:H7 in these products

This study investigated the prevalence and numbers of Enterobacteriaceae in minced beef and beef burgers purchased from supermarkets and butcher shops in the Republic of Ireland (RoI). Samples (n=1303) collected between June 2001 and April 2002 from every county in the RoI (∼60 per county) were examined for the presence of Enterobacteriaceae using method BS 5763. Overall, in the 43 beef products in which E. coli O157:H7 was present the Enterobacteriaceae counts ranged from 0.52 to 6.98 log₁₀ cfu g⁻¹. There was no correlation between the number of Enterobacteriaceae and the presence of E. coli O157:H7. There were no significant differences between Enterobacteriaceae numbers in fresh, unpackaged, minced beef samples from butcher shops and supermarkets, or in fresh, unpackaged, beef burgers from butcher shops and supermarkets. However, there were significant differences among the numbers of Enterobacteriaceae detected in different minced beef products. The numbers of Enterobacteriaceae in fresh, unpackaged, minced beef (6.54–6.98 log₁₀ cfu g⁻¹) were considerably higher than in preprepared or prepackaged minced beef (2.95–3.62 log₁₀ cfu g⁻¹).     

Effects of context and repeated exposure on food liking: The case of boar taint

This study investigated whether consumer acceptance of boar meat is overestimated by standardised situational testing and whether repeated exposure decreases liking. Thus, a home use test (HUT) followed by a central location test (CLT) was conducted to assess the acceptance of minced boar meat with approximately 14% fat either HIGH or LOW in androstenone (2.0 vs. 0.30 ppm) and skatole (0.30 vs. 0.06 ppm) in comparison to meat from castrates and gilts (CONTROL). In HUT, no significant difference (p > .05) in dislike frequency was observed between CONTROL and LOW. For HIGH, liking was strongly impaired during frying. The results indicated a masking effect of the ready-made sauce on the odour but not on the flavour. In CLT, dissatisfaction was generally higher than in HUT. Similar to HUT, HIGH boar meat was more often disliked (p < .001) compared to LOW and CONTROL in the CLT. To conclude, standardised testing did not underestimate acceptance. In contrast to anticipations, a single previous exposure to boar meat with high levels of androstenone and skatole did not affect (p > .05) liking in the follow-up CLT.     

Prediction of the nanomechanical properties of apple tissue during its ripening process from its firmness,color and microstructural parameters

Nanomechanical properties of fruit determine macroscopic firmness. Young's modulus (YM) of apple tissue obtained by atomic force microscopy (AFM) at cellular level and its correlation with other macroscopic physical parameters are used to evaluate ripening when apples were stored at 25 °C during 40 days. The YM of the tissue decreased from 0.96 ± 0.42 MPa (first day) to 0.11 ± 0.06 MPa (last day). The best linear correlation of YM was obtained with firmness (F) which decreased from 21.15 ± 0.79 N to 12.74 ± 0.34 N. Also various physical parameters obtained as peel color difference (ΔE) from 57.80 ± 0.97 to 66.51 ± 0.71, environmental electron microscopy (ESEM) such as entropy: Ent (from 8.67 ± 0.12 to 9.60 ± 0.17) and fractal dimension: FD (from 2.67 ± 0.05 to 2.75 ± 0.03) changed as well. Significant correlations (P < 0.05) were found between YM, F, ΔE, Ent and FD using Pearson analysis. Predictive models to evaluate YM from F, ΔE, Ent, FD were obtained by multiple linear regression, R² > 0.95 was found.Industrial relevanceThe study of the nanomechanical properties of fruit cells by AFM may provide insight into internally fruit properties and how changes in these properties over time influence the quality of the fruit. The determination of cell/tissue mechanics could be used to follow changes in the nanomechanical properties that occur during the processing and storage of climacteric fruits such as apples. The study of the nanomechanical properties of plant cells as well as their correlation with other useful food properties such as firmness, peel color and image texture could lead to a better understanding of the ripening process. Mathematical models to predict cell mechanical properties at the nanometric level through food quality parameters could be an innovation in food engineering and be a novel tool in evaluating the quality of apples. Benefits of the methods herein could be extended to address current issues, such as extending the storage life of other climacteric fruits and predicting nanostructural modifications to the cells when they are physically modified or chemically treated.     

Investigation of the effects of commercial carcass suspension (24 and 48 h) on meat quality in high oxygen modified atmosphere packed beef steaks during chill storage

Hanging for 24 or 48 hours (h) of intact carcasses in the chill store cooler prior to further processing occurs periodically at processor level due to demand for product. The aim of the study was to investigate the effects of commercial carcass suspension (24 and 48 h) on meat tenderness attributes in modified atmosphere packed beef steaks during chill storage. A secondary objective was to investigate protein oxidation reactions occurring and the subsequent meat tenderness consequences. Carcasses were hung for 24 or 48 h in order to reproduce commercial short term storage of meat at processor level. Experimental gas atmospheres used in packs consisted of; 40%, 50%, 60%, 70% and 80% oxygen, with all packs containing 20% CO₂ and the remainder being provided by the filler gas N₂. Steaks from the 24 h suspended carcasses were tougher than those from 48 h suspended muscle. Additionally, packaging systems with high oxygen had a negative influence on tenderness (instrumental) and consumer determined juiciness in cooked beef steaks. The carbonyl content and TBARS numbers increased to the greatest extent in high oxygen packed samples. Protein oxidation was directionally and significantly correlated (P < 0.01) to the higher O₂ treatments. Protein and lipid oxidation also occurred to a greater extent in the samples from the 48 h treatment, possibly due to physical matrix differences in the meat compared to the 24 h treatment. Meat from the 48 h treatment appeared less red than meat from the 24 h treatment.     

Effect of pre-incubation conditions on growth and survival of Staphylococcus aureus in sliced cooked chicken breast

In this work, the effect of pre-incubation conditions (temperature: 10, 15, 37 °C; pH 5.5, 6.5 and water activity, a_w: 0.997, 0.960) was evaluated on the subsequent growth, survival and enterotoxin production (SE) of Staphylococcus aureus in cooked chicken breast incubated at 10 and 20 °C. Results showed the ability of S. aureus to survive at 10 °C when pre-incubated at low a_w (0.960) what could constitute a food risk if osmotic stressed cells of S. aureus which form biofilms survive on dried surfaces, and they are transferred to cooked meat products by cross-contamination. Regarding growth at 20 °C, cells pre-incubated at pH 5.5 and a_w 0.960 had a longer lag phase and a slower maximum growth rate. On the contrary, it was highlighted that pre-incubation at optimal conditions (37 °C/pH 6.5/a_w 0.997) produced a better adaptation and a faster growth in meat products what would lead to a higher SE production. These findings can support the adoption of management strategies and preventive measures in food industries leading to avoid growth and SE production in meat products.