Microbial Shelf Life Research Articles

Brining as an effective method to stabilise sea lettuce (Ulva fenestrata) -impact on colour, texture, chemical characteristics and microbial dynamics

Brining as a cost-effective stabilising method to preserve the quality of fresh Ulva fenestrata was studied. The brines contained from 0 to 25 % (w/w) of sodium chloride or from 0 to 50 % sucrose and were combined with seaweed at a ratio of 1: 10 (w/v) prior to storage at 4 °C for up to 3 months. During this storage, the water activity of U. fenestrata was reduced from 0.94 to ≤0.89 with ≥15 % salt brines, which kept the microbial load <7 log (CFU/g) for 78 days. Among the sucrose brines, 50 % provided microbial shelf life <7 log (CFU/g) for 48 days. Further, 25 % salt or 50 % sucrose brines effectively retained the greenness (a*) of the U. fenestrata blades (< −20 a*-value for 80 days), while the tensile strength was only retained with 25 % salt brine (>3 Newton for 80 days). There was a time-dependent loss of crude proteins and fatty acids during storage, especially for 50 % sugar brined seaweed, where 58 % and 28 %, respectively, were lost after 20 days. Nutrients were best preserved in the 5 % salt-brine. Overall, the results indicate that brining with 25 % salt or 50 % sugar yields microbial stability and maintained colour of U. fenestrata for at least 48 days, with the former even exceeding 78 days at 4 °C, however, at a cost of nutritional value.

Development of active chitosan film containing bacterial cellulose nanofibers and silver nanoparticles for bread packaging.

The objective was to develop an active chitosan-based coating and to evaluate its effect on the shelf life and microbial safety of bread. Bacterial cellulose nanofibers (BCNF) and various levels (0.5%, 1%, and 2%) of silver nanoparticles (AgNPs) were in the chitosan (CS) film. Characterization of films was determined by analyzing WVP, ultraviolet barrier, and opacity as well as FTIR, XRD, DSC, TGA, and SEM. The water vapor permeability (WVP) of CS was remarkably (p < .05) decreased from 3.75 × 10-10 to 0.85 × 10-10 g/smPa when filled with BCNF and 2% AgNPs. Thermal and structural properties were enhanced in nanoparticle-included films. Applying CS/BCNF/AgNPs coatings for bread samples demonstrated a significant improvement in moisture retention and a decrease in the hardness (from 10.2 to 7.05 N for CS and CS/BCNF/1% AgNPs coated samples, respectively). Moreover, microbial shelf life of bread sample increased from 5 to 38 days after packaging with CS/BCNF/2% AgNPs film. After a storage period of 15 days at 25°C, no fungal growth was detected in bread samples which were coated with nanocomposite suspensions containing 1% and 2% AgNPs. However, at the same condition, yeast and mold counts was 7.91 log CFU/g for control sample. In conclusion, the CS/BCNF/2% AgNPs film might have the potential for use as active packaging of bread.

Extension of chicken fillets shelf life using genetically improved probiotic strain and chitosan

Fresh poultry meat products are perishable and need to be protected from spoilage. New or modified preservation techniques are needed to overcome the limitations of the traditional techniques. Therefore, six different coating solutions were evaluated to extend the shelf life of chicken fillets under refrigeration condition. The novel chitosan-based mix (T6) containing a bacteriocins-hyperproducer fusant, EDTA and sodium acetate was the treatment of choice since it improved film properties such as the reduction of water vapor permeability and the enhancement of the antimicrobial effect. Coating chicken fillets with the T6 mix resulted in improving both of the quality and shelf life of fillets. T6 recorded the lowest TBA value (1.25) compared to 4.77 mg malondialdehyde Kg−1 of the control at the end of the cold storage. Also, it extended the microbial shelf life up to 35 days by extending both of the lag phase and generation time of spoilage microorganisms by 6 days and 44.31 h, respectively. At the same time, T6 samples exhibited the highest sensory scores. It is strongly believed that such novel preservation system could be easily applied to extend the shelf life of many of the fresh foods since it was successfully applied to extend the shelf life of fresh chicken fillets by more than 31 days compared to control with high quality.

Variations in quality attributes of pulsed light-treated table grape juice during refrigerated storage (4°C) and ambient conditions (25°C).

Pulsed light (PL) pasteurization is being explored as a substitute for the conventional thermal pasteurization of juices in recent times due to better retention of nutrients and overall quality. However, the long-term stability of the PL-pasteurized juice must be investigated to promote its application by the industry. The effect of PL treatment (effective fluence of 1.15 J·cm-2) and thermal treatment (90°C for 60 s) on microbial quality, enzyme activity, bioactive compounds, sensory acceptance, and color profile of table grape juice during storage at 4 and 25°C was investigated in this study. The PL pasteurization enhanced the microbial shelf-life of the juice (<6 log10cfu·mL-1) from 5 to 35 days at 4°C. The PL and thermally-pasteurized juice demonstrated a shelf-life of only 10 days when stored at 25°C. The total soluble solids and titratable acidity did not alter significantly throughout the storage period. The peroxidase, polyphenol oxidase, and pectin methylesterase activities were below 10% for the PL and thermally-treated beverage when stored at 4°C. The sensory acceptability of the PL-pasteurized juice after 35 days of refrigerated storage (6.9±0.3) was close to the untreated juice (7.2±0.3) and greater than thermally-treated juice (6.2±0.2). After the 35th day of storage at 4°C, PL-treated grape juice retained 55%, 12%, and 15.3% more phenolics, flavonoids, and antioxidant capacity, respectively, than the thermally-pasteurized juice. Hence, PL pasteurization can effectively prolong the shelf-life of table grape juice while achieving microbial and enzymatic stability, along with high sensory and nutritional appeal. PRACTICAL APPLICATION: Exploring non-thermal methods like pulsed light (PL) pasteurization as a substitute for conventional thermal methods is gaining recognition for its ability to retain nutrients and improve overall juice quality. However, the industry's adoption depends on understanding the shelf-stability of PL-pasteurized juice. This study specifically investigates the practical applications of PL treatment in comparison with conventional thermal treatment in enhancing microbial safety and enzymatic stability in table grape juice. The findings contribute insights into optimizing the shelf life of table grape juice and preserving its quality, supported by microbial, enzymatic, and sensory evaluations.

The effect of rosemary, ginger, or garlic on microbial shelf life and sensory acceptability of nutritionally enriched cassava-based pancake (Kabalagala)

Iron and vitamin A contents of Cassava-based pancake (Kabalagala), a delicacy among children in northern Uganda have recently been improved through the addition of biofortified iron-rich beans and orange-fleshed sweet potato. The nutritionally improved product (NIK) was designed as a strategy to address iron and vitamin A deficiencies which are endemic challenges among children in Uganda. However, the NIK had a lower microbial shelf life (24 h) than the original product (72 h). The objective of this study was to investigate the potential of the spices; rosemary, ginger, and garlic to improve the microbial shelf life of the NIK. Each of the spices was used individually to prepare NIK at a rate of 0.5, 0.75, and 1 %. The resultant products were evaluated for counts of total microbial load, Enterobacteriaceae, lactic acid bacteria, yeasts and molds as well as consumer sensory acceptability during storage at ambient temperature. Results of One-way Analysis of Variance (ANOVA) showed that all the spices exhibited potency against the microbial groups investigated only when included in the NIK at 0.75 % or 1 % (p < 0.05). The microbial shelf life of the NIK based on total microbial count increased from 24 to 72 h depending on the spice type and concentration. The spice, 1 % ginger resulted in Enterobacteriaceae and yeast and molds counts within acceptable microbial threshold for the entire storage time (72 h) with a maximum load of 3.41 and 2.82 log10 CFU/g, respectively. The NIK containing ginger or garlic at 0.75 or 1 %, was more accepted and the extent of acceptability increased with storage time (p < 0.05). Based on the overall acceptability, the consumer acceptability varied from 1 % garlic >0.75 % garlic >1 % ginger >0.75 % ginger >0.5 % ginger in decreasing order. Spearman's correlation analysis revealed a strong association between the sensory parameters examined (appearance, aroma, texture, taste) and the overall acceptability of the products (p < 0.05). The magnitude of association between appearance, aroma, texture, taste and overall acceptability varied between 0.396–0.703, 0.504–0.679, 0.452–0.589, and 0.498–0.698, respectively. This study has demonstrated that ginger or garlic when applied at 0.75–1 % improves microbial shelf life of NIK concomitant with better consumer sensory acceptability. Therefore, ginger or garlic can be applied at 0.75–1 % to produce microbiologically and sensorially acceptable NIK for use to improve intake of vitamin A and iron among children in Uganda.

The Use of Predictive Microbiology for the Prediction of the Shelf Life of Food Products.

Microbial shelf life refers to the duration of time during which a food product remains safe for consumption in terms of its microbiological quality. Predictive microbiology is a field of science that focuses on using mathematical models and computational techniques to predict the growth, survival, and behaviour of microorganisms in food and other environments. This approach allows researchers, food producers, and regulatory bodies to assess the potential risks associated with microbial contamination and spoilage, enabling informed decisions to be made regarding food safety, quality, and shelf life. Two-step and one-step modelling approaches are modelling techniques with primary and secondary models being used, while the machine learning approach does not require using primary and secondary models for describing the quantitative behaviour of microorganisms, leading to the spoilage of food products. This comprehensive review delves into the various modelling techniques that have found applications in predictive food microbiology for estimating the shelf life of food products. By examining the strengths, limitations, and implications of the different approaches, this review provides an invaluable resource for researchers and practitioners seeking to enhance the accuracy and reliability of microbial shelf life predictions. Ultimately, a deeper understanding of these techniques promises to advance the domain of predictive food microbiology, fostering improved food safety practices, reduced waste, and heightened consumer confidence.

Microbacterium represents an emerging microorganism of concern in microfiltered extended shelf-life milk products

Growing interest in the manufacture of extended shelf-life (ESL) milk, which is typically achieved by a high temperature treatment called ultra-pasteurization (UP), is driven by distribution challenges, efforts to reduce food waste, and more. Even though high temperature, short time (HTST) pasteurized milk has a substantially shorter shelf-life than UP milk, HTST milk is preferred in the United States because consumers tend to perceive UP milk as less desirable due to the "cooked" flavor associated with high-temperature processing. While ESL beyond 21 d may be possible for HTST, the survival and outgrowth of psychrotolerant aerobic spore-forming bacteria can still be a limitation to extending shelf-life of HTST milk. Microfiltration (MF) is effective for reducing vegetative microorganisms and spores in raw milk, but it is unclear what the effects of membrane pore size, storage temperature, and milk type (i.e., skim vs whole) are on the microbial shelf-life of milk processed by both MF and HTST pasteurization. To investigate these factors, raw skim milk was MF using different pore sizes (0.8 μm or 1.2 μm), and then MF skim milk and standardized whole milk [MF skim with heat-treated (85°C for 20 s) cream] were HTST pasteurized at 75°C for 20 s. Subsequently, milk was stored at 3, 6.5, or 10°C and total bacteria counts were measured for up to 63 d. An ANOVA indicated that mean bacterial concentrations between storage temperatures were significantly different from each other, with mean maximum observed concentrations of 3.67, 5.33, and 8.08 log10 cfu/mL for storage temperatures 3, 6.5, and 10°C, respectively. Additionally, a smaller difference in mean maximum bacterial concentrations throughout shelf-life was identified between pore sizes (<1 log cfu/mL), but no significant difference was attributed to milk type. An unexpected outcome of this study was the identification of Microbacterium as a major contributor to the bacterial population in MF ESL milk. Microbacterium is a psychrotolerant, thermoduric gram-positive, non-spore forming rod with a small cell size (∼0.9 μm length and ∼0.3 μm width), which was able to permeate the membranes used in this study, survive HTST pasteurization, and then grow at refrigeration temperatures. While spores continue to be a key concern for the manufacture of MF, ESL milk, our study demonstrates the importance of other psychrotolerant, thermoduric bacteria such as Microbacterium to these products.

Coagulation temperature and smoking time determine product quality and shelf life of the acid-heat coagulated Circassian cheese.

This study examined the effects of process parameters on acid-heat coagulated Circassian cheese. For this purpose, cheeses were produced at coagulation temperatures of 70°C and 90°C, and smoked for 0, 2.5, and 6 h in both summer and winter. Microbiological, textural, proteolytic, and sensorial changes were observed for 90 days at 30-day intervals. According to the results, coagulation at 90°C instead of 70°C formed a firmer structure. Six-hour smoking time instead of 2.5-h provided higher dry matter, reduced proteolysis rates, and extended the microbial shelf life. In addition, higher (6 h) smoking decelerated sourness while resulting in intense smoke flavor and higher lipolytic activity. In conclusion, seasonal changes in milk and applied the process conditions revealed significant differences in the quality parameters and shelf life of acid-heat coagulated Circassian cheese.

The usage of sourdough powder as the natural preservative and glycemic index lowering agent in salty muffins

PurposeThe article aimed to use sourdough powder as a natural preservative against mould growth and a glycemic index reducer agent.Design/methodology/approachIn this study, muffin production was carried out with sourdough powder addition at the rate of 0, 15 and 30%. To obtain the sourdough powder, sourdough was fermented by using Lactobacillus fermentum, Lactococcus lactis (previously isolated from spontaneous sourdough) and Saccharomyces cerevisiae.FindingsThe specific volume, number of crumb pores and total pore area were not adversely affected by the addition of 15% or 30% sourdough powder (p > 0.05). The sourdough addition reduced the L* values of the muffin crust, while the b* value of the muffin crumb with 30% sourdough powder decreased compared to the control (p < 0.05). The addition of sourdough powder decreased eGI and RDS values and increased SDS content of samples (p < 0.05). In storage, the mould growth was observed in the control group and samples containing 15% sourdough powder on the 5th day, while the samples containing 30% sourdough powder were moulded on the 7th day. The sourdough powder increased the hardness and chewiness values of samples (p < 0.05), while it had no significant effect on springiness, cohesiveness and resilience (p > 0.05).Originality/valueThe sourdough powder provides a lower glycemic index and longer microbial shelf life that makes the product advantageous in consumer demand. This is the first time sourdough powder has been used to achieve this purpose.

A Systematic Review: Current Technology of Solid Carrier Formulation to Improve Viability and Effectiveness of Nitrogen-Fixing Inoculant

Biofertilizers are a promising alternative solution to reduce the long-term adverse effects of chemical fertilizers and are increasingly important for promoting sustainable agriculture. Unfortunately, biofertilizers have a relatively short shelf life, and microbial effectiveness often decreases during storage and application. Therefore, innovation is needed regarding the formulation of biological fertilizer carriers that have the potential to maintain microbial viability and effectivity during storage. The comprehensive study was carried out using Systematic Literature Review (SLR) method by the search engine to evaluate and assess the current status of solid carrier formulation to improve the viability and effectiveness of biofertilizers inoculants. The results of a systematic review of scientific literature were obtained from as many as 149 articles from ScienceDirect and Scopus, and a total of 10 articles were chosen for further review. Several carrier materials have been reported can increase the viability and effectiveness of N-fixing inoculant. Each carrier material provides various benefits, such as increased microbial shelf life, microbial activity, and plant growth. Some carrier materials have the potential for further development in Indonesia.

Digital twins for selecting the optimal ventilated strawberry packaging based on the unique hygrothermal conditions of a shipment from farm to retailer

Berries are one of the most challenging products to preserve after harvest due to their high perishability and short shelf life. Ventilated packaging plays a key role in maintaining fruit quality along the supply chain. However, every supply chain is composed of different unit operations, and every shipment encounters unique hygrothermal conditions such as air temperature fluctuations over time, sub-optimal humidity conditions, and the risk of condensation. Therefore, every supply chain has an optimal packaging that provides the best hygrothermal climate and ventilation to the fruit. Given the vast space of potential supply chain scenarios and packaging configurations, in-silico studies are an attractive alternative for selecting this optimal packaging. In this study, we developed physics-based digital twins for ventilated packaging of strawberries. We utilized measured air temperature and humidity data from an actual supply chain from the farm to the retail store. With these digital twins, we mimicked in-silico how the strawberries evolve hygrothermally, physiologically, and microbiologically along the supply chain inside 21 different types of ventilated packaging. We predicted actionable metrics of fruit quality and shelf life for these 21 packages. These metrics include total mass loss, risk of putative mold infection due to Botrytis cinerea, retention time of condensate, and remaining shelf life based on respiration, transpiration, and mold growth. In addition, we analyzed the impact of package-related metrics, such as total vent area, degree of filling, pressure drop across the package, and seven-eighths cooling time, on fruit quality metrics. With this approach, we pinpointed the critical quality loss points in the supply chain for every package. We identified the package that performs best in balancing the three-way trade-off between the respiration-driven biochemical shelf life, transpiration-driven physical shelf life, and mold growth-driven microbial shelf life of fruit. Our findings showed that the performance of open trays is comparable to ventilated clamshells, as long as a high humidity is maintained along the supply chain. Flow-wrapped packages presented the highest risk of condensation and microbial growth. We also quantified the spatial heterogeneity in fruit quality within the packages and highlighted the most vulnerable locations for quality loss inside each packaging type. Our study presents a novel, holistic approach to select the optimal ventilated packaging of strawberries from farm to retailer based on its measured hygrothermal fingerprint. This approach can help reduce food loss and contribute towards making supply chains smart and efficient.

Assessing the Protein-Ligand Interaction and Thermally Induced Quality Changes in Tomato-Based Pineapple Beverage

The intake of tomato in its natural form is comparatively restricted due to its limited shelf-life. Thereby, we investigated the willingness of consumers and optimized the proportions of beverages on the basis of the overall liking of the sensory panel. Further, molecular docking was also performed to evaluate the protein-ligand interactions of vitamin C, lycopene, and β-carotene against CR protein. These compounds showed great interactions with the protein targets leading to the enhancement of antioxidant activity. The most acceptable combination (S4 = 50:50 tomato and pineapple juices) was subjected to thermal processing at 70, 80, and 90 °C, respectively. Biochemical parameters such as acidity, vitamin C, non-enzymatic browning, antioxidant capacity, and total phenolics were found to be optimum in the beverage samples treated at 80 °C. It was revealed that the microbial shelf-life of beverages enhanced with an increase in processing temperatures. The untreated beverage samples could only retain a shelf-life of 4 days, however, samples treated at 80 °C for 60 s were rendered fit for 40 ± 2 days. Therefore, with the help of molecular docking, this manuscript assessed the protein-ligand interaction with the thermally induced quality changes in tomato-based beverages.

Nutritionally Enriched Muffins from Roselle Calyx Extract Using Response Surface Methodology.

Hibiscus sabdariffa, often called Roselle, is a flowering plant with a variety of traditional medicinal uses. Its calyx, with a bright and attractive red color, produces a tart and pleasant acidic taste. The purpose of this study was to develop a Roselle muffin and assess the acceptability, nutrition, and shelf life of the muffin using its ingredients. The muffin was developed using different formulations in different proportions resulting from Response Surface Methodology (RSM). Sensory parameters were used to assess the muffin's acceptability. According to the findings, the combination of extract volume 45.37 mL, citric acid 1.11 g, and sodium bicarbonate 1.67 g produces the best muffin, with the panelist's sensory scores reaching up to 84%. The outcome of the study suggests muffins baked with the Roselle calyx extract have high antioxidant (12.53 ± 0.13)%, anthocyanin (126.63 ± 1.96) mg Cyn-3-glu/100 g, phenolic (12.91 ± 0.69) mg GAE/100 g, and ascorbic acid (12.10 ± 0.89) mg/100 g contents. The microbial shelf life of the developed muffin is estimated to be 6 days at room temperature. The study findings can therefore be utilized in the development of foods containing Roselle calyx extract.

Responsive packaging based on imine-chitosan films for extending the shelf-life of refrigerated fresh-cut pineapple

Reversible imine chemistry has been employed to stabilize antimicrobial liquid volatiles trans-2-hexenal (HX) and salicylaldehyde (SL) to the surface of chitosan films. The reactivity of both aldehydes to amine groups of chitosan was high and the synthesis of imine bonds was assessed by ATR-FTIR. The hydrolysis of the bonds and the release of the aldehydes depended on the pH of the medium. Films exerted in vitro microbiocidal effect against E. coli, S. cerevisae and pineapple wild yeast when were immersed at pH 3.6. Finally, films were incorporated in the double-bottom of plastic containers filled with fresh-cut pineapple maintained at 4 °C for 18 days. Juice leakage from pineapple pieces triggered the release of aldehydes to the headspace of the package. Both aldehydes extended microbiological shelf-life of fruit and slowed down browning. SL increased juice leakage from fruit and affected firmness negatively. • Responsive antimicrobial packages prolonged microbial shelf-life of pineapple pieces. • Imine-chitosan films based on reversible covalent grafting of bioactive aldehydes. • Pineapple exudate triggers the hydrolysis of imine bond and release of antifungals. • Effective triggering mechanism for the release of hexenal and salicylaldehyde from films. • Hexenal and salicylaldehyde delayed browning of pineapple pieces.

English

In Senegal, traditional baobab (Adansonia digitata L.) fruit nectar (T-BFN) is the most popular drink from baobab fruit pulp and its consumption helps to fight poverty, malnutrition and generate income along the Senegalese value chain of non-timbered forest products. However, for a better competitiveness in the local market, traditional baobab fruit nectar must be microbiologically stable with an attractive visual aspect. The aim of this study is to evaluate the microbial quality during storage, and the impact of some treatments like homogenization on the visual appearance of traditional baobab fruit nectar processed in Senegal. The microbial shelf-life of pasteurized traditional baobab fruit nectar and the effect of homogenization at 0, 5, 8, 12, 13 and 14 MPa on the stability of visual appearance during storage have been studied. Pasteurized traditional baobab fruit nectar could be stored up to 190 days at 4&deg;C without microbial spoilage. Homogenization at 14MPa stabilized the visual appearance of traditional baobab fruit nectar without sedimentation of the pulp or clarification for days at 4&deg;C. In combination with pasteurization, homogenization may be addressed as an effective tool to prevent pulp sedimentation in traditional bottled baobab fruit nectar. &nbsp; Key words: Baobab fruit nectar, microbial quality, visual appearance, storage, homogenization pressure, pulp sedimentation.

Microbial quality of gamma-irradiated dried Roselle (Hibiscus sabdariffa L.) calyx powder

The influence of gamma irradiation on the microbial shelf life of Hibiscus sabdariffa (Roselle) calyx powder was determined in this study. Roselle calyx powder samples were procured from a local market, packaged in high-density polyethylene bag, irradiated at 0, 2, 4, 6, 8 and 10 kGy and then stored at ambient temperature (27 ± 3 °C) for 3 months. During the storage period, samples were taken at 0, 1, 2 and 3 months for microbial analysis. Gamma irradiation doses (2, 4 and 6 kGy) significantly reduced the microbial load of the dried calyx powder. Microbial counts were not detected in samples irradiated at 8 and 10 kGy. This implies that gamma irradiation doses of 8 and 10 kGy completely eliminated microorganisms in the samples. Decontamination using gamma irradiation improves the microbial shelf life of Roselle calyx powder.

Melissa officinalis essential oil as an antimicrobial agent against Listeria monocytogenes in watermelon juice

The burden of foodborne illness has a negative effect on public health, but also in countries' economy. Melissa officinalis is an aromatic plant known for its biological properties, including antioxidant and antimicrobial effects. This work highlighted M. officinalis essential oil's antioxidant potential and antimicrobial activity against L. monocytogenes, presenting a bactericidal action and being able to inhibit some virulence attributes, such as biofilm formation. The pre-exposure of the bacterium to subinhibitory levels of essential oil (0.125 μL/mL) did not induce high tolerance to stresses (such as high temperature, low pH, osmotic stress and desiccation) or cross-resistance with antibiotics, while not modifying the invasion ability to Caco-2 cells. When applied in food model media (lettuce, chicken and milk) and watermelon juice, the essential oil showed to have antimicrobial activity in a lettuce leaf model medium, further diminishing L. monocytogenes contamination and inhibiting the natural microbiota present in watermelon juice. M. officinalis essential oil shows potential to be used as control of L. monocytogenes in watermelon juice, while increasing the food's microbial shelf life.

Improving the microbial and nutritional quality of skim milk using microfiltration combined with thermal and nonthermal techniques

The effectiveness of microfiltration (MF), alone or combined with high temperature short time (HTST) pasteurisation, ultraviolet-C (UV-C), and ultrasonication (US) in improving the microbial and nutritional quality of skim milk was evaluated in comparison with commercial ultra-pasteurisation (UP). Compared with untreated skim milk, MF combined with UV-C and US retained more bioactive proteins, which made these techniques superior to MF combined with HTST. Almost no bioactive proteins survived after UP. MF alone reduced the bacterial load by 2.5 log; however, MF combined with HTST (MH), UV-C (MUV), or US (MUS) can reduce the bacterial load to an undetectable level and extend the microbial shelf-life of skim milk to 40 days. In addition, MUV and MUS did not induce significant protein oxidation. Even though the skim milk after MUV or MUS showed only minor microbial growth, the shelf-life was limited by proteolysis through plasmin activity.

Changes in quality attributes of pulsed light and thermally treated mixed fruit beverages during refrigerated storage (4 °C) condition

The effect of batch pulsed light (PL) irradiation (3000 J cm−2) on the shelf-life of the beverage blend comprising apple ber (Indian jujube), carambola (star fruit), and black table grapes was investigated. The equivalent thermally treated beverage (90 °C|5 min) exhibited greater stability from microbial and enzymatic spoilage but retained 27% less antioxidants and 14% less vitamin C than PL-treated juice. Thermally and PL-treated blends possessed sensory scores of 5.8 and 7.2, respectively. The beverage's microbial shelf-life (population ≤ 6-log10 cfu/mL) was extended to 45 days at 4 °C after the PL treatment. The PL exposure did not alter the pH and soluble solids during storage. The PL-treated juice, after 45 days, was placed on par with the freshly prepared juice by the sensory panel. The PL-treated juice preserved 61% more antioxidants, 38.8% more phenolics, and 68.2% more vitamin C than the thermally pasteurized beverage after 45 days of refrigerated storage. Industrial relevanceWhile the fruit processing industry demands microbial safety and enzymatic stability, today's consumer demands juices of high nutritional quality. This study utilizes under-explored fruits like apple ber (Indian jujube) and carambola (star fruit) to make a shelf-stable mixed fruit beverage. This study will help the industry understand the potential of PL treatment in accomplishing microbial safety, enzymatic stability, and nutritional quality, along with the utilization of under-explored fruits.

Fate of natural bacterial flora, and artificially inoculated Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica in raw ground chicken meat with added oregano oil or tannic acid alone or combined

The antibacterial effect of oregano oil and tannic acid (TA) on the aerobic plate count (APC), Enterobacteriaceae (ENT), Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica in raw ground chicken breast meat (RGCBM) held at 4 °C and 10 °C was studied. Five treatments including i) control (no antimicrobial), ii) 200 ppm oregano oil, iii) 10 ppm TA, iv) 200 ppm oregano oil + 10 ppm TA, and v) 5 ppm butylated hydroxy anisole (BHA) were prepared. Oregano oil, TA, and BHA inhibited increases in the APC when used separately (P < 0.05). Oregano oil + TA exhibited a higher (P < 0.05) antibacterial effect on APC during storage of RGCBM at 4 °C and 10 °C. Also, that same combination significantly (P < 0.05) inhibited growth of E. coli O157:H7, L. monocytogenes, S. enterica, and ENT in the meat irrespective of storage temperature. However, from a practical perspective, pathogen inhibition is unlikely to be deemed effective. Based on these results, the antibacterial activity of oregano oil is improved by TA, and the oregano oil + TA combination has good potential for controlling growth of native bacterial flora to enhance the microbial shelf-life of RGCBM.