Lipid production from sweet sorghum bagasse through yeast fermentation

Cryptococcus curvatus has great potential in fermenting unconditioned hydrolysates of sweet sorghum bagasse. With hydrolysates obtained by enzymatic hydrolysis of the solid pretreated by microwave with lime, the maximal yeast cell dry weight and lipid content were 10.83 g/l and 73.26%, respectively. For hydrolysates obtained in the same way but without lime, these two parameters were 15.50 g/l and 63.98%, respectively. During yeast fermentation, glucose and xylose were consumed simultaneously while cellobiose was released from the residual bagasse. The presence of lime, on one hand, made cellulose more accessible to enzymes as evidenced by higher total reducing sugar release compared to that without during enzymatic hydrolysis step; on the other hand, it caused the degradation of sugars to non-sugar chemicals during pretreatment step. As a result, higher lipid yield of 0.11 g/g bagasse or 0.65 ton/hectare of land was achieved from the pathway of microwave pretreatment and enzymatic hydrolysis while 0.09 g/g bagasse or 0.51 ton/hectare of land was attained from the process of lime-assisted microwave pretreatment followed by the same enzymatic saccharification.     

Wavelet Analysis of Signals in Agriculture and Food Quality Inspection

Food quality and safety have become the top priorities for agriculture and food processing industry due to the increasing consumer demand for high-quality healthy food. The food processing industry is currently focusing on using fast, precise, and nondestructive automated quality inspection techniques. Near-infrared spectroscopy, image processing, hyperspectral imaging, X-rays, and ultrasonic techniques have been researched and shown to have high potential for automated inspection. The biggest challenge in the automated inspection systems deals with signal pre-processing, denoising, feature extraction, and its re-synthesis for classification purposes. Several research studies have established that the technique of wavelet analysis can very well resolve these issues of signal processing in many systems used for quality inspection of agricultural and food products. The objective of this paper is to discuss the theory of wavelet analysis and review its application in signal processing and feature extraction for quality monitoring of agricultural and food products.     

Nanoencapsulation and immobilization of cinnamaldehyde for developing antimicrobial food packaging material

Use of antimicrobial coatings on food packaging is one of the important technologies of active packaging for improving food safety. There is growing demand for natural antimicrobials because of fear of adverse health effects of synthetic preservatives. The objectives of this study were to compare antibacterial properties of free and nanoencapsulated cinnamaldehyde in solution; polylactic acid (PLA) surfaces cast with cinnamaldehyde; and glass and PLA surfaces coated with cinnamaldehyde nano-liposomes. Cinnamaldehyde was nano-encapsulated by lipid bilayers of polydiacetylene – N-hydroxysuccinimide (PDA–NHS) nano liposomes and immobilized on glass slides and PLA films. Glass surfaces immobilized with nano-encapsulated cinnamaldehyde showed significant antibacterial activity against Escherichia coli W1485 and Bacillus cereus ATCC 14579, with reductions of 2.56 log₁₀ CFU/ml and 1.59 log₁₀ CFU/ml respectively in 48 h. PLA films cast with cinnamaldehyde also showed significant antibacterial activities against E. coli W1485 (2.01 log₁₀ CFU/ml reduction) and B. cereus (4.81 log₁₀ CFU/ml reduction). However, when the liposomal encapsulated cinnamaldehyde was immobilized on PLA films, it did not show any antibacterial activity. Glass surfaces coated with nano-encapsulated cinnamaldehyde may be used as an active packaging material in preserving liquid foods; however, further study is required to improve antimicrobial activities of PLA surfaces.     

UV-C treatment of soymilk in coiled tube UV reactors for inactivation of Escherichia coli W1485 and Bacillus cereus endospores

Coiled tube UV reactors were used to investigate the influence of tube diameter (1.6 mm ID, and 3.2 mm ID) and Reynolds number (Re) to inactivate Escherichia coli W1485 and Bacillus cereus spores in raw soymilk (RSM). Four levels of Re (343, 686, 1029 and 1372) were tested in RSM inoculated separately with each bacterium and treated in the UV reactors at a constant residence time of 11.3 s with UV-C dose of 11.187 mJ/cm² at 253.7 nm. Inactivation efficiency of both microorganisms increased with Re. Maximum reductions of 5.6 log₁₀ CFU/ml of E. coli and 3.29 log₁₀ CFU/ml of B. cereus spores were achieved in the 1.6 mm ID UV reactor. Inactivation efficiency was higher in the 1.6 mm ID UV reactor than the 3.2 mm ID UV reactor for both the organisms. Effect of UV-C light on lipid oxidation of untreated RSM, measured as malondialdehyde and other reactive substances (MORS) content, was much higher (95 nmol/ml) than the UV-treated (58 nmol/ml) and thermally pasteurized (55 nmol/ml) RSM during the storage period of 7 days. The UV-C treatment can be effectively used for reducing E. coli cells and B. cereus spores in soymilk without compromising its quality.