Ropiness in Bread-A Re-Emerging Spoilage Phenomenon

Isolation and Characterization of a Bacillus amyloliquefaciens Bacteriophage JBA6 and Its Endolysin PlyJBA6

Bacillus amyloliquefaciens is a Gram-positive, aerobic, spore-forming bacteria usually found in soil. Despite its probiotic potential, B. amyloliquefaciens has been identified as a cause of food spoilage, including the development of off-odors, rope formation, and the production of viscous substances in a wide range of foods. To control B. amyloliquefaciens, we isolated three B. amyloliquefaciens bacteriophages TBA3, JBA3, JBA6, and characterized one representative JBA6 endolysin, PlyJBA6. Transmission electron microscopy and genomic analysis demonstrated that all three phages belong to the Salasmaviridae family, characterized by short, non-contractile tails with linear dsDNA genomes ranging from 18.7 to 19.1 kb. PlyJBA6 contains a glycoside hydrolase family 24 domain (PF00959) at the N-terminus and two LysM domains (PF04176) at the C-terminus. While JBA6 has a narrow host range, infecting only 7 out of 9 tested strains of B. amyloliquefaciens, PlyJBA6 exhibits extended lytic range beyond the Bacillus genus. Interestingly, PlyJBA6 lyses Gram-negative bacteria such as Escherichia coli, Yersinia enterocolitica and Cronobacter sakazakii without other additives to destabilize bacterial outer membrane. We assume that JBA6 might be a useful component for a phage cocktail to control B. amyloliquefaciens and that PlyJBA6 can provide insights into the development of novel biocontrol agents against various food-borne pathogens.

Foodborne spore-forming bacteria: Challenges and opportunities for their control through the food production chain

Foodborne spore-forming bacteria represent a significant challenge within the food production chain due to their widespread occurrence and resistance to various processing methods. In addition to their role in food spoilage, these bacteria exhibit pathogenic properties, posing risks to public health. A comprehensive understanding of the impact of unit operations along the food production continuum, from farm or field to fork, is essential for ensuring both the safety and quality of food products. This chapter explores the factors influencing the growth, inactivation, and persistence of these bacteria, as well as the challenges and opportunities for their control. The discussion encompasses preventive measures, control strategies at the farm and field levels, and processing operations, including both thermal and non-thermal methods. Post-processing controls, such as storage and distribution practices, are also addressed. Furthermore, consumer behavior, education, and lessons learned from past outbreaks and product recalls contribute to a broader understanding of how to manage spore-forming bacteria within the food production chain. By assessing and quantifying the effects of each processing step, it becomes possible to implement effective control measures, thereby ensuring microbiological safety and enhancing the quality of food products.

Supernatant of plant-associated bacteria potency against biofilms formed by foodborne pathogen and food spoilage bacteria

OBJECTIVES

Food products are often contaminated by pathogens and spoilage bacteria. Most of them can form biofilms, a community of cells embedded in protective extracellular matrix layers resistant to harsh conditions, including antibiotics. Therefore, alternative antibiofilm agents are required to overcome biofilm formation. This study aims to determine and quantify the antibiofilm activity of supernatants from plant-associated bacteria against biofilms of foodborne pathogen and food spoilage bacterium, namely Bacillus cereus and Bacillus subtilis.

RESULTS

Plant-associated bacteria (PAB) have shown promising antibiofilm activities against biofilm-forming pathogens in previous studies. Thirteen PAB isolated from Ternate, Indonesia were used in this study. Supernatants of PAB were subjected to antimicrobial activity and quorum quenching detection, both using the well diffusion method. Four supernatants inhibited the growth of B. subtilis, but none affected the growth of B. cereus. Eight supernatants were able to disrupt the quorum sensing system of an indicator bacterium, wild-type Chromobacterium violaceum. Biofilm inhibition and destruction were quantified using 96-well microplates. The highest biofilm inhibition and destruction activities of PAB supernatants against each of B. cereus and B. subtilis biofilms were > 76%, and were later confirmed by light microscope and scanning electron microscope. Brine shrimp lethality assay (BSLA) was conducted and revealed that the selected PAB supernatants were non-toxic. The 16S rRNA gene of PAB were sequenced and they showed similarities to Bacillus, Priestia, and Chryseobacterium. Compounds in the supernatants were determined by GC-MS which revealed contents of fatty acids, ethyl esters, and diketopiperazines. Therefore, PAB supernatants have potential as antibiofilm agents against biofilm formed by Bacillus cereus and Bacillus subtilis.

Microbiological Quality Assessment of Some Commercially Available Breads

Bread is a staple, energy-rich food for people of all ages, so quality is important to consumers. In our region, most of the commercially available bread, whether packaged or unpackaged, is produced by local bakeries, so monitoring microbial levels and the types of microbes present on bread can help to draw attention to protect the final product. It can also help to ensure the food safety, quality, and shelf life of bread. The freshly baked product is microbiologically sterile. Post-process contamination affects the microbial load of bread. In this study, the microbial load of 30 different commercial bread crumbs and crusts was determined. The different types of bread with different compositions were analyzed for total viable bacteria, Escherichia coli, Staphylococcus aureus, aerobic and anaerobic spore-forming bacteria, and culturable microscopic fungi. The K-means clustering algorithm was used to cluster the different types of bread based on the number of aerobic mesophilic bacteria. Significant differences (p < 0.05) were found in the total viable bacterial count for bread crusts and crumbs. The bacterial count of bread varied between 10.00 ± 0.00-395.00 ± 52.4 CFU/g for bread crusts and 10.00 ± 0.0-310.67 ± 94 CFU/g for bread crumbs. The results of 16S rDNA sequence analysis showed that the most frequently occurring bacterial species belonged to the genus Bacillus, but species of the genus Staphylococcus were also present. Chryseobacterium spp. predominated on multigrain bread, Marinilactobacillus spp. on rustic potato bread, and Staphylococcus warneri on sliced brown potato bread. The results contribute to a better understanding of the microbial dynamics in locally produced breads from the Eastern Carpathians of Transylvania, with the aim of improving food safety, quality control, and consumer protection.

Enhancing food safety: A low-cost biosensor for Bacillus licheniformis detection in food products

To enhance food safety, the need for swift and precise detection of B. licheniformis, a bacterium prevalent in various environments, including soil and food products, is paramount. This study presents an innovative and cost-effective bioassay designed to specifically identify the foodborne pathogen, B. licheniformis, utilizing a colorimetric signal approach. The biosensor, featuring a 3D-printed architecture, incorporates a casein-based liquid-proof gelatine film, selectively liquefying in response to the caseinolytic/proteolytic activity of external enzymes from the pathogen. As the sample liquefies, it progresses through a color layer, causing the migration of dye to an absorbent layer, resulting in a distinct positive signal. This bioassay exhibits exceptional sensitivity, detecting concentrations as low as 1 CFU/mL within a 9.3-h assay duration. Notably, this cost-efficient bioassay outperforms conventional methods in terms of efficacy and cost-effectiveness, offering a straightforward solution for promptly detecting B. licheniformis in food samples.

Psyllium and okra mucilage as co-carrier wall materials for fenugreek oil encapsulation and its utilization as fat replacers in pan bread and biscuit production

This study aimed to investigate the potential use of okra and psyllium mucilage as co-carrier wall materials with whey protein and gum Arabic polymers for encapsulation of fenugreek oil to mask its undesirable flavor and promote their health benefits. Particle size, zeta potential, encapsulation efficiency, morphological properties and fatty acid profiles of crude and encapsulated oils were examined using zeta-sizer, SEM and GC-MS techniques. Crude and encapsulated fenugreek oils were added as functional ingredients during production of pan bread and biscuits. The quality characteristics (baking quality, color and organoleptic properties) of bread and biscuits as well as microbiological properties of bred samples were evaluated. Results showed that the forming microcapsules had sphere particles with the size of 5.05 and 31.64 μm for okra and pysillium mucilage, respectively and had smooth continuous surfaces with no holes or fractures. Fatty acids analysis showed that fenugreek oil is superior functional edible oil, rich in unsaturated fatty acids. The organoleptic properties of products were improved when fat replaced with encapsulated fenugreek oil with okra or psyllium mucilage. Likewise, encapsulated fenugreek oil showed antimicrobial activity in bread samples during storage period. On contrary, Bread and biscuits incorporated with crude fenugreek oil gained the lowest scores for all organoleptic parameters. Regarding these results, encapsulated fenugreek oil presents good fat alternatives in dough formulations with acceptable technological, sensory and antimicrobial properties. However, further investigations still needed regarding the biological activity of encapsulated fenugreek oil and its utilization as a food supplement in other food products.

Microbial ecology and metabolite dynamics of backslopped triticale sourdough productions and the impact of scale

Triticale (X Triticosecale Wittmack) is a hybrid of wheat (Triticum aestivum L.) and rye (Secale cereale L.), combining the positive attributes of both cereals. However, it has not been exploited for sourdough production yet. Further, the effect of scale on sourdough production has not been investigated systematically up to now. The aims of the present study were to assess the microbial ecology and metabolomic output of eleven spontaneously fermented, backslopped sourdough productions made with triticale flour on a scale of 100, 200, 500, and 1000 g. The acidification profile [pH and total titratable acidity (TTA)], microbial diversity (culture-dependent and culture-independent), metabolite dynamics, and appropriate correlations were determined. After ten fermentation steps, different species of Lactobacillaceae were prevalent in the mature sourdoughs, in particular Latilactobacillus curvatus, Limosilactobacillus fermentum, and Pediococcus pentosaceus. The microbial diversity could be traced back to the grains and was also present in the milling fractions (flour, bran, and shorts). Furthermore, thanks to the use of Illumina-based high-throughput sequencing and an amplicon sequence variant (ASV) approach, the presence of undesirable bacterial groups (bacilli, clostridia, and enterobacteria) during the initial steps of the backslopping cycle was revealed, as well as a finetuned taxonomic diversity of the LAB genera involved. Small sourdough productions (100 and 200 g) selected for a lower species diversity and reached a stable consortium faster than large ones (500 and 1000 g). Although a comparable final pH of 3.6-4.0 was obtained, the TTA of small sourdoughs was lower than that of large ones. Regarding the metabolic output, the simultaneous production of mannitol and erythritol, beyond ethanol and glycerol, could be linked to sourdoughs in which Liml. fermentum was the sole LAB species present. Further, the use of the arginine deiminase pathway by P. pentosaceus and Liml. fermentum was obvious. An appropriate extraction method followed by liquid injection gas chromatography coupled to triple quadrupole tandem mass spectrometry allowed the quantification of interesting volatile organic compounds, such as ethyl lactate. These findings support the inclusion of triticale as a viable alternative to wheat or rye for the production of sourdoughs that can be integrated into bread-making production schemes.

Microbiological quality of some packed and unpacked bread products in Alexandria, Egypt

BACKGROUND

Bakery products are important food snacks consumed by people of all ages and economic groups. The growth of unwanted microorganisms that deteriorate products such as bacteria, moulds, and fungi in these foodstuffs may offer risks to consumers' health and generate considerable economic losses. This work aimed to assess the microbiological quality of some packed and unpacked bread products in Alexandria, Egypt.

METHODS

This cross-sectional comparative study involved 168 local and branded bakery products that were collected randomly from 2 districts in Alexandria. Hygienic practices such as covering of the bread and wearing gloves during handling were observed and recorded. All bread samples were tested to determine the total plate count (TPC), presence/absence of Staphylococcus aureus (S. aureus), total yeasts and moulds in CFU/g and total coliform count (TC) in MPN/g.

RESULTS

The mean of the total yeasts and moulds and TC in the packed bread was lower than that of the unpacked bread (3.40 × 103 CFU/g and 3.25 MPN/g versus 6.37 × 103 CFU/g and 31.61 MPN/g, respectively). However, the mean of TPC in the packed bread was higher than that of the unpacked bread (1.39 × 106 versus 2.07 × 105 CFU/g, respectively). The mean TPC, total yeasts and moulds and TC was higher in the studied flatbread than Fino bread and toast (3.4 × 106, 1.14 × 104 CFU/g and 24.6 MPN/g, respectively). The presence of S. aureus was higher in flat, unpacked bread, bread displayed outside the shop and handled without gloves.

CONCLUSION

Bread produced by local bakeries showed lower standards in packaging and microbial quality. Better manufacturing, packaging, storage, and handling initiatives should be introduced to avoid related food safety concerns in the future. The formal authorities should define and clarify standards and rules on bread safety.

Linking microbial contamination to food spoilage and food waste: the role of smart packaging, spoilage risk assessments, and date labeling

Ensuring a safe and adequate food supply is a cornerstone of human health and food security. However, a significant portion of the food produced for human consumption is wasted annually on a global scale. Reducing harvest and postharvest food waste, waste during food processing, as well as food waste at the consumer level, have been key objectives of improving and maintaining sustainability. These issues can range from damage during processing, handling, and transport, to the use of inappropriate or outdated systems, and storage and packaging-related issues. Microbial growth and (cross)contamination during harvest, processing, and packaging, which causes spoilage and safety issues in both fresh and packaged foods, is an overarching issue contributing to food waste. Microbial causes of food spoilage are typically bacterial or fungal in nature and can impact fresh, processed, and packaged foods. Moreover, spoilage can be influenced by the intrinsic factors of the food (water activity, pH), initial load of the microorganism and its interaction with the surrounding microflora, and external factors such as temperature abuse and food acidity, among others. Considering this multifaceted nature of the food system and the factors driving microbial spoilage, there is an immediate need for the use of novel approaches to predict and potentially prevent the occurrence of such spoilage to minimize food waste at the harvest, post-harvest, processing, and consumer levels. Quantitative microbial spoilage risk assessment (QMSRA) is a predictive framework that analyzes information on microbial behavior under the various conditions encountered within the food ecosystem, while employing a probabilistic approach to account for uncertainty and variability. Widespread adoption of the QMSRA approach could help in predicting and preventing the occurrence of spoilage along the food chain. Alternatively, the use of advanced packaging technologies would serve as a direct prevention strategy, potentially minimizing (cross)contamination and assuring the safe handling of foods, in order to reduce food waste at the post-harvest and retail stages. Finally, increasing transparency and consumer knowledge regarding food date labels, which typically are indicators of food quality rather than food safety, could also contribute to reduced food waste at the consumer level. The objective of this review is to highlight the impact of microbial spoilage and (cross)contamination events on food loss and waste. The review also discusses some novel methods to mitigate food spoilage and food loss and waste, and ensure the quality and safety of our food supply.

Microbial and Qualitative Traits of Quinoa and Amaranth Seeds from Experimental Fields in Southern Italy

Quinoa and amaranth are of special interest since they are increasingly used for the development of new bakery products with enhanced nutritional value. The aim of the study was to evaluate the agronomic, microbiological, and nutritional characteristics of quinoa and amaranth seeds grown in Southern Italy. For this reason, quinoa Titicaca and three amaranth accessions (5, 12, and 14) were cultivated in different experimental fields in the Campania Region and analyzed for the cultivation aspects, chemical composition, and microbiological quality of the seeds. All seeds showed a good adaptability to cultivation in the experimental areas of the Mediterranean basin. Quinoa seeds were characterized by their higher protein, fat, and ash content than the amaranth seeds, which were characterized by their higher value in dietary fiber. All seeds, regardless of the geographical area of production, were contaminated with yeasts, moulds, and spore-forming bacteria, mainly Bacillus cereus, B. licheniformis, B. safensis and B. subtilis, as identified by 16S rRNA sequencing analysis. So, the detection of Bacillus spp. must be strongly monitored, as quinoa and amaranth seeds could be used in bread production, where they can cause ropiness, resulting in great economic losses for the industries.

Breadsticks Flavoured with Olives and Onions: One-Year Shelf Life

In this work, we compared breadsticks (known as Treccine) flavoured with onions and olives and prepared with olive pomace oil (OPO) or with extra virgin olive oil (EVOO). The effect on one-year shelf life was also studied. The following physical, chemical and sensory analyses were conducted on the breadsticks: water activity, moisture content, colour, texture and sensory analysis (appearance, colour, flavour, taste, texture and overall acceptability). For the oil extracted from the Treccine, we determined acidity, peroxide value, spectrophotometric parameters, ABTS and DPPH assay on the hydrolitic fraction, DPPH on the lipid fraction, and fatty acids. We detected a progressive deterioration in the quality of breadsticks with a decrease in shelf life after 4-6 months in relation to each studied parameter. In the analysed breadsticks, water activity was 0.342 (OPO recipe) and 0.387 (EVOO recipe) after one-year storage; in the same storage period, the moisture content was 6.34 times (OPO) and 5.32 times (EVOO) greater. Appearance and colour were the only two sensory parameters which, after 12 months, remained above or equal to five stated as the minimum quality value. In the extracted oil, Free acidity increased from 0.35 to 0.56% (OPO) and from 0.71 to 0.98% (EVOO); Peroxide value ranged between 6.10 and 102.89 meq/kg oil (OPO) and between 4.41 and 20.91 meq/kg oil (EVOO). K232 was highest in OPO (2.43-3.70) and lowest in EVOO (1.76-2.92), K268 was 1.32-1.580 (OPO recipe) and 0.570-0.640 (EVOO recipe). Treccine prepared with extra virgin olive oil showed better biological properties and longer shelf life.

Exploring the Inhibitory Activity of Selected Lactic Acid Bacteria against Bread Rope Spoilage Agents

In this study, a wide pool of lactic acid bacteria strains deposited in two recognized culture collections was tested against ropy bread spoilage bacteria, specifically belonging to Bacillus spp., Paenibacillus spp., and Lysinibacillus spp. High-throughput and ex vivo screening assays were performed to select the best candidates. They were further investigated to detect the production of active antimicrobial metabolites and bacteriocins. Moreover, technological and safety features were assessed to value their suitability as biocontrol agents for the production of clean-label bakery products. The most prominent inhibitory activities were shown by four strains of Lactiplantibacillus plantarum (NFICC19, NFICC 72, NFICC163, and NFICC 293), two strains of Pediococcus pentosaceus (NFICC10 and NFICC341), and Leuconostoc citreum NFICC28. Moreover, the whole genome sequencing of the selected LAB strains and the in silico analysis showed that some of the strains contain operons for bacteriocins; however, no significant evidence was observed phenotypically.

Food grade nanoemulsion development to control food spoilage microorganisms on bread surface

In this study, the effect of emulsifier mixture and their concentrations on the development of nanoemulsion was studied. The impact of sonication and microfluidization processing conditions on the physicochemical properties and in vitro antimicrobial activity was also evaluated. The optimal nanoemulsion formulation was then evaluated on bread surface against B. subtilis. Results showed that a hydrophilic-lipophilic balance HLB = 12 and emulsifier: oil ratio of 1:1 allowed the formation of stable nanoemulsion. Also, both microfluidization and sonication allowed the formation of nanoscale-emulsion. Sonication treatment for 10 min allowed a maintain the total flavonoid content and a slight reduction of total phenol content. Furthermore, employing sonication resulted to the lowest polydispersity index suggesting more stable nanoemulsion. Nanoscale-emulsion showed a good in vitro antimicrobial activity against L. monocytogenes and E. coli. The application of nanoemulsion on bread surface inoculated with B. subtilis showed a delay of the decay.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-022-05660-5.