Application of ultrasound technology for functional meat products

With increasing consumer awareness of health and nutrition, the meat processing industry is eager to engage in a search for innovative ways of processing and developing novel meat products with potential health benefits. Novel processing technologies including ultrasound (US) technology can offer several benefits for versatile applications in food processing. In relation to meat processing, US technology has previously been investigated for many potential applications including accelerated brining, tenderisation, rapid cooking, faster thawing and decontamination of muscle-based food products. This thesis assesses the feasibility of employing US technology to assist in the development of functional meat products. To achieve this objective, a series of five studies were carried out. The first study investigated the efficacy of high intensity US on the fermentation profile of Lactobacillus sakei (a starter culture used for meat fermentation) in a meat model system. This study observed that both stimulation and retardation of L. sakei is possible, depending on the ultrasonic power and sonication time employed. Furthermore, to underline the fundamental mechanism influencing the behaviour of microorganisms subjected to ultrasonic frequencies of 20, 45, 130 and 950 kHz on growth kinetics, phenotypic behaviour and cell morphology were assessed in study 2. Results presented in this study showed that the physiological response of L. sakei to US is frequency-dependent and US can influence metabolic pathways. The influence of US frequency on the behaviour of L. sakei culture in a meat matrix was also studied. Additionally, this study investigated possible synergistic effects between US and L. sakei addition on drying kinetics, moisture mobility and key nutritional (fatty acid profile, protein, amino acids, and organic acids) in beef jerky samples. Given the complexity and number of parameters involved, a reliable multivariate statistical strategy was adopted. The results presented in this study showed a significant effect of US pre-treatment on various physicochemical properties as a result of employing both L. sakei and US. The individual effects of L. sakei and US were prominent compared to interactive effects. Conversely, the effect of US frequency on L. sakei culture observed in model systems (Chapter 2 and 3) was not evident when assessed in a solid meat matrix. Two specific studies were carried out to investigate US-assisted diffusion of ingredients into meat matrices with the objective of improving the nutritional profile and healthy image of meat. Results from salt diffusion studies showed improved diffusion rates for sodium salt compared to a static brining system can be obtained. However, no significant differences were observed in the case of sodium salt replacers. A second aspect of US-assisted diffusion focused on the incorporation of essential fatty acids (FA) to improve the lipid profile of pork meat. This study has demonstrated the positive effect of US application in improving diffusion of encapsulated FA into meat, thereby resulting in higher levels of essential FA compared to the static diffusion system. It can be concluded from the thesis work conducted that the effectiveness of US technology is application dependent. The commercial utilisation of US technology remains challenging for solid food applications, especially for meat products due to the complex nature of meat. However, further research is needed prior to commercial uptake of US technology for a range of applications

Investigating the influence of ultrasound pre-treatment on drying kinetics and moisture migration measurement in Lactobacillus sakei cultured and uncultured beef jerky

Low Frequency-Nuclear Magnetic Resonance (LF-NMR) was employed to elucidate changes in water distribution in cultured (Lactobacillus sakei) and uncultured beef jerky samples subjected to ultrasound pre-treatment. Ultrasound pre-treatment at frequencies of 25, 33 and 45 kHz for 30 min, followed by marination (18 h) was carried out for both cultured and uncultured jerky samples. Among the various kinetic models assessed, the Wang and Singh model provided the closest fit to the drying experimental data, with high R2 (≥0.994), low RMSE (≤0.023) and low AICc (100 ms (T22), respectively. Results presented in this study demonstrates that the ultrasound effect on drying behaviour was frequency dependent and that LF-NMR can be employed to evaluate moisture mobility and drying degree of beef jerky

Exploitation of Ultrasound Technique for Enhancement of Microbial Metabolites Production

Microbial metabolites have significant impacts on our lives from providing valuable compounds for nutrition to agriculture and healthcare. Ever-growing demand for these natural compounds has led to the need for smart and efficient production techniques. Ultrasound is a multi-applicable technology widely exploited in a range of industries such as chemical, medical, biotechnological, pharmaceutical, and food processes. Depending on the type of ultrasound employed, it can be used to either monitor or drive fermentation processes. Ultrasonication can improve bioproduct productivity via intensifying the performance of living organisms. Controlled ultrasonication can influence the metabolites' biosynthesis efficiency and growth rates by improvement of cell permeability as well as mass transfer and nutrient uptake rates through cell membranes. This review contains a summarized description about suitable microbial metabolites and the applications of ultrasound technique for enhancement of the production of these metabolites as well as the associated downstream processing

Statistical approaches to access the effect of Lactobacillus sakei culture and ultrasound frequency on fatty acid profile of beef jerky

The objective of this study was to investigate the effect of ultrasonic frequencies and drying time on fatty acid profiles of beef jerky samples possessing different microbial compositions. Beef slices were cured using curing solutions formulated both with and without Lactobacillus sakei. Curing was carried out for 18 h at 4 °C prior to hot air drying at 60 °C for 4 h. Jerky samples from both treatment groups were then subjected to ultrasonic frequencies of 25 kHz, 33 kHz and 45 kHz for 30 min. Beef jerky samples were subsequently analysed for fatty acid profile using Gas Chromatography. In the present study, beef slices showed a high level of MUFAs, which accounted for 45.6–53.8%, followed by the SFAs (36.3–47.8%) and PUFAs (4.8–13.7%), respectively. Results demonstrated a significant effect of beef jerky processing on fatty acid profile. Various correlation analyses showed that changes in fatty acid profiles were significantly affected by individual and/or interactive effects of L. sakei, drying time and ultrasonic frequency

Effect of Narrowband UV-B Irradiation on the Growth Performance of House Crickets

Indoor co-cultivation systems can answer to the need for sustainable and resilient food production systems. Rearing organisms under light-emitting diodes (LEDs) irradiation provides the possibility to control and shape the emitted light spectra. UV-B-irradiation (280–315 nm) can positively affect the nutritional composition of different plants and other organisms, whereas information on edible insects is scarce. To evaluate the potential effect of the photosynthetically active radiation (PAR) and LED-emitting LEDs on the rearing and nutritional quality of edible insects, house crickets (Acheta domesticus) were reared from the age of 21 days under controlled LED spectra, with an additional UV-B (0.08 W/m2) dose of 1.15 KJm2 d−1 (illuminated over a period for 4 h per day) for 34 days. UV-B exposure showed no harm to the weight of the crickets and significantly increased their survival by ca. 10% under narrowband UV-B treatment. The nutritional composition including proteins, fat and chitin contents of the insects was not affected by the UV-B light and reached values of 60.03 ± 10.41, 22.38 ± 2.12 and 9.33 ± 1.21%, respectively, under the LED irradiation. Therefore, house crickets can grow under LED irradiation with a positive effect of narrowband UV-B application on their survival

Evaluating an emerging technology-based biorefinery for edible house crickets

IntroductionEdible insects, specifically house crickets, are expected to play an important role in the future food systems due to their rich nutritional profile, low environmental impact and growing consumer acceptance as food. Their content of proteins, lipids, chitin and phenolics offer great potential for the valorization of their biomass into nutritional end products and fractions. Furthermore, emerging food processing technologies and green solvents are relevant for improving the valorization process.Materials and methodsHigh pressure (HP) and ultrasound (US) processing were implemented in an insect biorefinery system, where a hexane/methanol/water solvent was used to separate fat, phenolics and a solid fraction containing proteins and chitin. Subsequently, a deep eutectic solvent of betaine and urea (B/U) was used to for protein and chitin isolation.ResultsA maximum of 15% of fat was isolated, with no positive effect from the US or HP treatments. The US treatment enhanced the phenolic extraction yield by 38.69%, while HP negatively affected the antioxidant capacity. B/U was efficient in separating proteins and chitin, resulting in a protein concentrate with a protein content ≥80% and a chitinous fraction with a chitin content ≥70%.ConclusionHouse cricket biomass can be refined into valuable fractions with a quick and simple method, making the process industrially relevant

Application of chemometrics to assess the influence of ultrasound frequency, Lactobacillus sakei culture and drying on beef jerky manufacture: Impact on amino acid profile, organic acids, texture and colour

The effects of ultrasound (US) frequency, addition of Lactobacillus sakei culture and drying time on key nutritional (protein, amino acids, and organic acids) and physicochemical properties (texture and colour) of cultured and uncultured beef jerky were evaluated. Cultured and uncultured jerky samples were subjected to US frequencies of 25 kHz, 33 kHz and 45 kHz for 30 min prior to marination and drying. Principal component analysis demonstrated a significant effect of beef jerky processing conditions on physicochemical properties. Taurine content of jerky samples was found to increase with an increase in ultrasonic frequencies for cultured samples. No significant changes in colour values were observed for ultrasound pre-treated and control samples. Interactive effects of culture treatment, drying and ultrasonic frequency were observed. This study demonstrates that the nutritional profile of beef jerky can be improved through the incorporation of L. sakei

Ultrasonic-assisted incorporation of nano-encapsulated omega-3 fatty acids to enhance the fatty acid profile of pork meat

In this study, ultrasound was employed to enhance the diffusion of microencapsulated fatty acids into pork meat. Nanovesicles of fish oil composed of 42% EPA (eicosapentanoic acid) and 16% DHA (docosahexanoic acid) were prepared using two different commercial Pronanosome preparations (Lipo-N and Lipo-CAT; which yield cationic and non-cationic nanovesicles, respectively). The thin film hydration (TFH) methodology was employed for encapsulation. Pork meat (Musculus semitendinosus) was submerged in the nanovesicles suspension and subjected to ultrasound (US) treatment at 25 kHz for either 30 or 60 min. Samples were analysed for fatty acid composition using gas chromatography-flame ionisation (GC-FID). The content of long-chain PUFAs, especially omega-3, was found to increase following the US treatment which was higher for Lipo-CAT compared to Lipo-N nanovesicles. Samples subjected to Lipo-N had higher atherogenic and thrombogenic indices, indicating higher levels of saturated fatty acids compared to the Lipo-CAT. The omega-6/omega-3 ratio in pork meat was significantly reduced following the US treatment, thus indicating an improved fatty acid profile of pork