3D printing: trends and approaches toward achieving long-term sustainability in the food industry.

Global food security has recently been under serious threat from the rapid rise in the world's population, the problems brought on by climate change, and the appearance of new pandemics. As a result, the need for novel and innovative solutions to solve the existing problems and improve food sustainability has become crucial. 3D printing is expected to play a significant role in providing tangible contributions to the food industry in achieving sustainable development goals. The 3D food printing holds the potential to produce highly customized food in terms of shape, texture, flavor, structure and nutritional value and enable us to create new unique formulations and edible alternatives. The problem of whether the cost of the printed meal and 3D printing itself can be sustainably produced is becoming more and more important due to global concerns. This review intends to provide a comprehensive overview of 3D printed foods with an overview of the current printing methodologies, illustrating the technology's influencing factors, and its applications in personalized nutrition, packaging, value addition, and valorization aspects to fully integrate sustainability concerns thus exploring the potential of 3D food printing.

Ultrasonic processing: effects on the physicochemical and microbiological aspects of dairy products.

Dairy products that are contaminated by pathogenic microorganisms through unhygienic farm practices, improper transportation, and inadequate quality control can cause foodborne illness. Furthermore, inadequate storage conditions can increase the microflora of natural spoilage, leading to rapid deterioration. Ultrasound processing is a popular technology used to improve the quality of milk products using high-frequency sound waves. It can improve food safety and shelf life by modifying milk protein and fats without negatively affecting nutritional profile and sensory properties, such as taste, texture, and flavor. Ultrasound processing is effective in eliminating pathogenic microorganisms, such as Salmonella, Escherichia coli, Staphylococcus aureus, and Listeria monocytogenes. However, the efficiency of processing is determined by the type of microorganism, pH, and temperature of the milk product, the frequency and intensity of the applied waves, as well as the sonication time. Ultrasound processing has been established to be a safe and environmentally friendly alternative to conventional heat-based processing technologies that lead to the degradation of milk quality. There are some disadvantages to using ultrasound processing, such as the initial high cost of setting it up, the production of free radicals, the deterioration of sensory properties, and the development of off-flavors with lengthened processing times. The aim of this review is to summarize current research in the field of ultrasound processing and discuss future directions.

Nutritional, antioxidant, and antimicrobial assessment of carrot powder and its application as a functional ingredient in probiotic soft cheese.

Carrots (the main source of carotenoids) have multiple nutritional and health benefits. The objectives of this study were to evaluate the compositional, antioxidant, and antimicrobial properties of carrot powder and to examine its effect on the sensory characteristics, chemical properties, and microbial viability of probiotic soft cheese at a rate of 0.2, 0.4, and 0.6%. The carrot was turned into powder before being analyzed and incorporated as an ingredient in making probiotic soft cheese. Probiotic soft cheese was made from buffalo milk. The buffalo milk (∼6.9% fat, 4.4% protein, 9.2% milk solids not fat, and 0.7% ash) was pasteurized at 75 ± 1°C for 5 min and cooled to 40-42°C. The milk was then divided into 4 aliquots. Sodium chloride (local market, Assiut, Egypt) was added at a ratio of 5% followed by starter cultures. The carrot powder (4.5% moisture, 4.8% ash, 2.7% fat, 8.2% protein, 11.9% fibers, and 72.3% carbohydrate) was added at a rate of 0.2, 0.4, and 0.6%, followed by addition of 0.02 g/kg rennet. The cheese was cut again into cubes, pickled in jars filled with whey, and stored for 28 d at 6 ± 1°C. The results of this study illustrated the nutritional and antioxidant properties of carrot powder. Incorporation of carrot powder in probiotic soft cheese affected the moisture and salt content at 0 d. The total bacteria count decreased from 7.5 to 7.3 log cfu/g in the cheese when carrot powder was used at a rate of 0.6%. The reduction of total bacteria count was noticed during the 28 d of storage by adding carrot powder. Furthermore, lactic acid bacteria and Bifidobacterium longum counts elevated with adding carrot powder during the 28 d of storage.

A fluorescence spectroscopic method for rapid detection of bacterial endospores: Proof of concept.

Current spore detection methods rely on culture techniques, with limitations of time, efficiency, and sensitivity. The bacterial spore coat contains calcium dipicolinic acid (CaDPA) as a major constituent, which could serve as a biomarker for bacterial endospores. We report proof of concept for a rapid and sensitive technique for the detection of bacterial endospores by using ratiometric fluorescence-based sensors. This method is based on the detection of CaDPA, which enhances the luminescence of lanthanide ions when complexed with a semiconducting polymer. A CaDPA standard curve was generated at an excitation-emission wavelength (λ) of λ275-λ544 by using a spectrophotometer. The intensity was recorded after chelating semiconducting fluorescent polyfluorene (PFO) dots with terbium (lanthanide) ions, sensitized by different volumes of CaDPA (0.1 µM). The resultant standard curve showed a linear relationship (R2 = 0.98) in the experimental concentration range of 2.5 to 25 nM CaDPA, with corresponding intensity (arbitrary units) of 545 to 2,130. Endospores of the aerobic sporeformer Bacillus licheniformis ATCC 14580 were produced at 37°C for 15 d on brain heart infusion agar plates. The efficiency of sporulation was evaluated by spore staining and plating techniques. Total CaDPA content on spores was estimated after suspending decreasing concentrations of spores (logs 9.0 through 1.0 cfu/mL, at 1-log intervals) in HPLC-grade water (to serve as control) and skim milk samples. In HPLC-grade water, for higher spiking levels such as (mean ± SD) 9.2 ± 0.03, 8.4 ± 0.05, 7.1 ± 0.13, and 6.3 ± 0.02 logs, the corresponding mean CaDPA from the standard curve were 9.4, 7.2, 6.2, and 5.3 nM, respectively. For lower spiking levels of 4.2 ± 0.05, 3.1 ± 0.04, 2.0 ± 0.11, and 1.36 ± 0.09 logs, we observed mean CaDPA contents of 3.8, 3.3, 2.2, and 1.3 nM, respectively. For raw skim milk spiked with B. licheniformis ATCC 14580 spores, the mean CaDPA content on spores was approximately 2.5, 3.8, and 5.0 nM for spiking levels of 5.21, 6.39, and 9.47 log cfu/mL, respectively. Trials were conducted in replicates of 3 and means were compared. Trials conducted using HPLC-grade water showed a linear relationship for the CaDPA content of endospores and for endospore counts with the standard CaDPA concentration curve. For skim milk-spiked samples, we observed reduced fluorescence detection, which was 5 times lower than that of spiked samples in HPLC-grade water. The reduced fluorescence in skim milk could be due to the turbidity of the solution or to interference from proteins, amino acids, and other ions in milk. This study thus provides proof of concept for a potential application of this technique to rapidly detect bacterial endospores in the dairy and food industry. Further work is required to remove the interference of ionic components in milk to improve detection limits in milk and other dairy product matrices such as cheese, whey proteins, and reconstituted powders.

Influence of probiotic adjunct cultures on the characteristics of low-fat Feta cheese.

There are different methods that have been recently applied to develop a process to manufacture low-fat Feta cheese (LFC) with acceptable flavor and texture. The objective of this study was to produce LFC from skim buffalo's milk (SBM) using Streptococcus thermophilus (ST) and Lactobacillus bulgaricus (LB) as control LFC (T1) incorporated with other probiotic adjunct cultures (PAC), such as Lactobacillus casei (LBC) in T2, Bifidobacterium bifidum (BB) in T3, and Lactococcus lactis subsp. lactis (LL) in T4. The SBM was pasteurized and inoculated with 3% of starter cultures; then, 0.4% of rennet and 3% of salt were added. After coagulation, the cheese was cut, packed, and stored at 4°C. The chemical, microbiological, and sensory characteristics of LFC were monitored during 14 days of storage. The moisture, acidity, total protein (TP), salt, and fat of LFC were approximately 75.0%, 1.0%, 17.0%, 3.0%, and 1.2%, respectively, after 14 days of storage at 4°C. The viability of PAC was high (5-7 log cfu/g) at the end of storage, which makes LFC a functional product with a valuable source of probiotic. Moreover, the adjunct cultures improved (p < .05) the sensory characteristics of LFC, including the texture and flavor.

Sporulating behavior of Bacillus licheniformis strains influences their population dynamics during raw milk holding.

To understand the role of strain variability, population dynamics of 2 strains of Bacillus licheniformis, ATCC 6634 and ATCC 14580, were modeled as a function of temperature (4.0-12.0°C) and duration (0-72 h) using regression analysis. Based on the initial spiking of vegetative cells (approximately 4.0 log cfu/mL) and spores (approximately 2.0 log cfu/mL), regression equations, elucidating B. licheniformis growth behavior during raw milk holding at low temperature, were obtained. Contour plots were developed to determine the time-temperature combinations, keeping the population changes to less than 1.0 log. In vegetative cell spiking study of B. licheniformis ATCC 6634 (S1), cell population changes remained below 1.0 log up to 72 h at 8°C. For B. licheniformis ATCC 14580 (S2), 1.0 log shift was not observed only after 80 h at 8°C, indicating higher multiplication potential of S1 as compared with S2. As S2 was a readily sporulating strain, the vegetative spiking study showed spore formation at different storage temperatures. Evidence of some parallel germination was observed for this strain at 8°C or higher, when raw milk samples were spiked with spores. The experimental values obtained for sporeformers and spore counts were validated with contour plot-generated values. Overall, for raw milk samples predominated by the low sporulating strain, the contour plots suggested holding at 8°C or below for up to 72 h. In the case of the readily sporulating strain (S2), raw milk could be held at 8°C for 80 h, where little or no sporulation is observed. Sporulation behavior, germination and multiplication ability, strain variability, and temperature and duration of holding raw milk influenced the population dynamics of Bacillus species. However, in the presence of equivalent numbers of both types of sporulating strains in raw milk, despite strain variability, holding milk at 8°C for not more than 72 h would keep any cell population changes below 1.0 log. In addition, under these storage conditions, the population would remain as vegetative cells that are likely to be inactivated by pasteurization. The contour plots, so generated, would help predict the population shifts and define optimum holding conditions for raw milk before further processing.