Band 15, Heft 10 -

The agricultural products are perishable in nature and possesses short shelf/storage life under ambient conditions. The temperature and humidity control systems are required to enhance to storage life of the products with optimum quality, quantity and nutritive attributes. In this regard, the significance of air-conditioning in storage application is highlighted along with the conventional storage options. The implications of compressor-based refrigeration and air-conditioning systems regarding low-cost and energy efficient air-conditioning systems are discussed in detailed. It is concluded that thermally driven air-conditioning systems can be used on top priority for the short-term storage of fresh agricultural products. Moreover, the long-term storage of products at freezing temperature can be made through hybrid systems instead of standalone conventional compressor based vapor compression refrigeration and/or air-conditioning systems. Finally, the air-conditioning systems are proposed for the optimum storage of different categorize of the food products.

Haematococcus pluvialis ( H. pluvialis ) can naturally accumulate high amounts of astaxanthin – a powerful antioxidant. However, complete recovery of astaxanthin from the cysts of H. pluvialis is challenging because of the presence of a robust acetolysis resistant cell wall. Herein, a simple and effective planetary ball-milling pretreatment was developed to rupture the cells to attain an almost complete recovery of astaxanthin from H. pluvialis , using a supercritical CO 2 and conventional organic solvent-based extraction. An optimized pretreatment using planetary ball mill under very mild conditions (150 rpm, 60 min) allowed the recovery of 31.4 mg/g dry weight of astaxanthin from H. pluvialis , while slightly harsh milling (500 rpm) was found to be detrimental toward astaxanthin. The extracts in acetone exhibited higher antioxidant activity in 1-diphenyl-2-picrylhydrazyl assay than those in dichloromethane. These mild conditions were safe and highly effective for the complete extraction of astaxanthin along with the others extractables. This study opens a new avenue for the efficient recovery of valuable thermolabile ketocarotenoid species from microalgae, which can be applied to the development of economically viable biorefineries.

Volatile profiling was carried out during heating through vacuum-assisted headspace solid-phase microextraction combined with gas chromatography-mass spectrometry to better understand the flavor forming mechanism of flour products. Ninety-two volatile compounds were detected and identified, including aldehydes (25), ketones (15), alcohols (9), nitrogen- and sulfur-containing compounds (6), benzene derivatives (15), furans (10), and acids and esters (12). The formation temperature of each volatile was also determined. Results showed that temperature played an important role in the formation and content of volatile compounds. In the low-temperature range (60 °C–100 °C), the flavor composition of flour was mainly composed of C6–C10 volatile aldehydes and alcohols. At temperatures exceeding 100 °C, especially at 120 °C, many long carbon chain aldehydes and alcohols, furans, acids, esters, nitrogen- and sulfur-containing compounds were formed. The formation rate of most identified volatile compounds increased during heating, especially from 90 °C to 130 °C.

In this study, sugar-free dark chocolate was produced from isomalt and maltitol by β V seeding technique as an alternative to conventional tempering process. The effect of β V seed concentrations on the particle size distribution, textural, rheological and melting properties of the end products was studied, and the results were compared with those of conventional sugar-free dark chocolates. For this aim, conched dark chocolates were melted and crystallized with β V seeds added at different concentrations (0.5, 0.6, 0.7, 0.8, 0.9 and 1.0 %, m/m). Conventional tempering process was performed by using temper machine (47–27–32 °C). Brightness, chroma, whiteness index and tetramethyl pyrazine content (as marker compounds of dark chocolate volatile compound) were not influenced by seeding technique compared to conventional tempering method. The water activity of the dark chocolate samples was substantially affected by β V seed level according to used bulk sweetener. However, all the values were determined below 0.4 which is critical limit for chocolate. Regarding overall acceptability, sugar-free dark chocolates tempered by β v seeds had very close scores compared with conventional one, implying that sugar-free chocolates can be produced by β v crystals with desired quality characteristics similar to conventional samples. Results of this study showed that it is possible to produce sucrose-free dark chocolates by using β V seeds with desired quality similar to chocolate produced by using conventional tempering.

In this study, air deflector plates were used in order to increase the air elapsed time in the chamber. The air flow pattern was simulated using computational fluid dynamics. The geometry of the chamber was produced in 2D and meshed by triangular and quadrilateral elements, boundary conditions were defined and the governing equations solved. Modeling of flow without any deflectors depicted the air flowed to the chamber conducted to the outlet without any distortion. Air vortices were generated when the deflectors defined in model. To evaluate the influence of deflectors on drying period, constructed plates installed in the dryer chamber and melon slices were dried when deflectors used or not. Simulation results showed magnitude of the air velocity was increased and temperature uniform distribution developed on the surface of trays. The outlet temperature was also decreased up to 10 % and drying time reduced to 22 % when the deflectors were employed.

This study aimed to investigate the effect of low-pressure dielectric barrier discharge (DBD) plasma on microwave-assisted hydrodistillation of lemon peel oil extraction. Microwave pre-treated lemon peel powder was exposed to plasma treatment (1.0, 1.5, 2.0, and 2.5 kV) for 10 min. The treated lemon peel powders were subjected to hydrodistillation to extract the essential oil and the extraction yields were calculated. The extracted oil was analyzed for chemical composition with gas chromatography-mass spectrometry (GC-MS). Effect of plasma on the surface morphology of the lemon peel was observed in a scanning electron microscope (SEM) which revealed the formation of fissures and cracks owing to the higher extraction yield. Plasma treatment at 2.5 kV was observed higher extraction yield than conventional hydrodistillation (149.34 % rise) and the chemical composition of plasma treated sample essential oil remains significantly unchanged. Thus, DBD plasma could be a promising technique to enhance the lemon peel essential oil extraction.

The study was performed to develop a non-culture method to quantify viable loads of Lactobacillus acidophilus NCFM using RNA-based molecular technique. The ‘growth curve’ and ‘cycle threshold curve’ were developed respectively by plate counting and using cycle threshold (C T ) values. ‘Standard curve’ was constructed using cells per milliliter and relative C T values. A maximum viable count (1.5 ± 0.15) × 10 10  cells/mL with a minimum C T value 20.18 ± 0.56 was achieved following 18 h of growth. The two parameters were inversely proportional to each other over the exponential growth. The ‘standard curve’ corresponded to equation y = 2E + 28e −2.034x (y = cells/mL, x = C T value; R 2  = 0.993), and no sample showed significant difference between ‘plate count’ and relative ‘PCR count’ following the validation process. Industrial adaptation of this method in dairy processing could potentially contribute to a faster enumeration of viable L. acidophilus NCFM compared to plate counting.