Cryogenics and its application with reference to spice grinding: a review

Mechanochemical Synthesis of Polyanilines and Their Nanocomposites: A Critical Review

The mechanochemical synthesis of polyanilines (PANIs), made by oxidative polymerization of anilines, is reviewed. First, previous knowledge of the polymerization reaction in solution is discussed to understand the effect of different parameters: oxidant/monomer ratio, added acid, oxidant, temperature and water content on the properties of the conducting polymers (molecular weight, degradation, doping/oxidation level, conductivity, and nanostructure). The work on mechanochemical polymerization (MCP) of anilines is analyzed in view of previous data in solution, and published data are critically reconsidered to clarify the interpretation of experimental results. A key factor is the production of acids during polymerization, which is often overlooked. The production of gaseous HCl during MCP of aniline hydrochloride is experimentally observed. Since some experiments involves the addition of small amounts of water, the kinetics and heat balance of the reaction with concentrated solutions were simulated. A simple experiment shows fast (<2 min) heating of the reaction mixture to the boiling point of water and temperature increments are observed during MCP in a mortar. The form and sizes of PANI nanostructures made by MCP or solution are compared. The extensive work on the production of nanocomposites by MCP of anilines together with different nanomaterials (porous clays, graphene, carbon nanotubes, metal, and oxide nanoparticles) is also described.

A Review: Sample Preparation and Chromatographic Technologies for Detection of Aflatoxins in Foods

As a class of mycotoxins with regulatory and public health significance, aflatoxins (e.g., aflatoxin B1, B2, G1 and G2) have attracted unparalleled attention from government, academia and industry due to their chronic and acute toxicity. Aflatoxins are secondary metabolites of various Aspergillus species, which are ubiquitous in the environment and can grow on a variety of crops whereby accumulation is impacted by climate influences. Consumption of foods and feeds contaminated by aflatoxins are hazardous to human and animal health, hence the detection and quantification of aflatoxins in foods and feeds is a priority from the viewpoint of food safety. Since the first purification and identification of aflatoxins from feeds in the 1960s, there have been continuous efforts to develop sensitive and rapid methods for the determination of aflatoxins. This review aims to provide a comprehensive overview on advances in aflatoxins analysis and highlights the importance of sample pretreatments, homogenization and various cleanup strategies used in the determination of aflatoxins. The use of liquid-liquid extraction (LLE), supercritical fluid extraction (SFE), solid phase extraction (SPE) and immunoaffinity column clean-up (IAC) and dilute and shoot for enhancing extraction efficiency and clean-up are discussed. Furthermore, the analytical techniques such as gas chromatography (GC), liquid chromatography (LC), mass spectrometry (MS), capillary electrophoresis (CE) and thin-layer chromatography (TLC) are compared in terms of identification, quantitation and throughput. Lastly, with the emergence of new techniques, the review culminates with prospects of promising technologies for aflatoxin analysis in the foreseeable future.

Relating Food Engineering to Cooking and Gastronomy

Modern consumers are increasingly eating meals away from home and are concerned about food quality, taste, and health aspects. Food engineering (FE) has traditionally been associated with the industrial processing of foods; however, most underlying phenomena related to FE also take place in the kitchen during meal preparation. Although chemists have positively interacted with acclaimed chefs and physicists have used foods as materials to demonstrate some of their theories, this has not been always the case with food engineers. This review addresses areas that may broaden the vision of FE by interfacing with cooking and gastronomy. Examples are presented where food materials science may shed light on otherwise empirical gastronomic formulations and cooking techniques. A review of contributions in modeling of food processing reveals that they can also be adapted to events going on in pots and ovens, and that results can be made available in simple terms to cooks. Industrial technologies, traditional and emerging, may be adapted to expand the collection of culinary transformations, while novel equipment, digital technologies, and laboratory instruments are equipping the 21st-century kitchens. FE should become a part of food innovation and entrepreneurship now being led by chefs. Finally, it is suggested that food engineers become integrated into gastronomy's concerns about safety, sustainability, nutrition, and a better food use.

Pulverizing processes affect the chemical quality and thermal property of black, white, and green pepper (Piper nigrum L.)

In this study, the effects of different pulverizing methods on the chemical attributes and thermal properties of black, white and green pepper were evaluated. Cryogenic grinding minimally damaged the lipid, moisture, crude protein, starch, non-volatile ether extract, piperine, essential oil and the typical pepper essential oil compounds of the spices. The pulverizing methods and storage significantly affected the compositions of the fatty acid in the peppers, except for palmitic acid and lignoceric acid. The amino acid contents and the thermo-gravimetric analysis curve were hardly influenced by the grinding techniques. The use of cryogenic grinding to prepare pepper ensured the highest quality of pepper products. Regardless of grinding technique, the values of moisture, piperine, unsaturated fatty acids, essential oil, monoterpenes, and the absolute concentrations of typical pepper essential oil constituents (except caryophyllene oxide) decreased, whereas the amino acid, lipid, protein, starch, and non-volatile ether extract content as well as the thermal properties were insignificantly changed after storage at 4 °C for 6 months.

Postharvest Processing and Benefits of Black Pepper, Coriander, Cinnamon, Fenugreek, and Turmeric Spices

Spices are prime source for flavor, aroma, and taste in cuisines and play an active role as medicines due to their high antioxidant properties. As medicine or food, the importance of spices cannot be overemphasized. The medicinal values of spices are very well established in treating various ailments like cancer, fever, malaria, stomach offset, nausea, and many more. A spice may be available in several forms: fresh, whole dried, or pre-ground dried which requires further processing to be utilized in the form of value-added product. This review paper deals with the cultivation, postharvesting, chemical composition, uses, health, and medicinal benefits of the selected spice viz., black pepper, coriander, cinnamon, fenugreek, turmeric, and technological advances in processing of spices viz., super critical fluid extraction, cryogenic grinding, and microencapsulation etc. This paper also focuses on issues related to utilization of spices toward its high end-product development and characterization in pharmaceuticals and other medicinal purposes. The availability of different spices and their varietal differences and location have their pertinent characters, which are much demanding to refine postharvest and processing to assure its quality in the international market.

The effect of cryogenic grinding and hammer milling on the flavour quality of ground pepper (Piper nigrum L.)

In this study, we compared the effects of cryogenic grinding and hammer milling on the flavour attributes of black, white, and green pepper. The flavour attributes were analysed using headspace solid-phase micro-extraction (HS-SPME) and gas chromatography-mass spectrometry (GC/MS), sensory evaluation and electronic nose (e-nose) analysis. Cryogenic grinding resulted in minimal damage to the colour, flavour, and sensory attributes of the spices. Cryogenic grinding was also better than hammer milling at preserving the main potent aroma constituents, but the concentrations of the main aroma constituents were dramatically reduced after storing the samples at 4 °C for 6 months. Pattern matching performed by the e-nose further supported our sensory and instrumental findings. Overall, cryogenic grinding was superior to hammer milling for preserving the sensory properties and flavour attributes of pepper without significantly affecting its quality. However, we found that the flavour quality of ground pepper was reduced during storage.