Valorization of tea waste: Composition, bioactivity, extraction methods, and utilization.

Tea is the most consumed beverage worldwide and has many health effects. Although there are many different types of tea, black tea and green tea comprise 98% of total tea production in the world. Tea waste production consists of withering, crushing, fermentation, drying and finally packaging processes. All of the waste generated during this production line is called tea waste. Tea production results in a significant amount of waste that cannot be effectively used for value creation. This waste contains many different components including protein, fiber, caffeine, and polyphenols. Due to its rich composition, it can be revalorized for different purposes. In this study, the general composition and bioactive compounds of tea waste were reviewed. Despite the fact that there have been few studies on the bioactivity of tea waste, those studies have also been discussed. The extraction techniques that are used to separate the compounds in the waste are also covered. It has been indicated that these valuable compounds, which can be separated from tea wastes by extraction methods, have the potential to be used for different purposes, such as biogas production, functional foods, food additives, silages, soluble packaging materials, and adsorbents. Although there are some studies on the revalorization of tea waste, new studies on the extraction of bioactive compounds are necessary to improve its utilization potential.

Effect of de-phenolization on protein-phenolic interactions of sunflower protein isolate.

Proteins and phenolic compounds are significant components of foods that can interact, and this interaction can impact the functional properties of proteins and the bioactivity of phenolic compounds. Sunflower meal, which has a high potential to be an important alternative protein source, contains phenolic compounds mostly bonded with proteins. In this study, the interaction between proteins and phenolic compounds which naturally exist in sunflower and prone to oxidation during alkaline treatment (for protein isolation) was investigated. There was a significant decrease up to 96.21% in the content of total phenolics by methanol washing. Chlorogenic acid, cryptochlorogenic acid and caffeic acid were detected in the phenolic extract obtained from sunflower protein isolate, and they exhibited different levels of reduction after methanol washing. For the total antioxidant capacity analysis, a decrease by 50% was observed after 4hwashing with methanol solution, and there was no significant decrease afterwards. In addition, the fluorescence intensity of sunflower protein was diminished with reduced washing time, which was mostly attributed to the protein-phenolic interaction. According to hydrodynamic parameters, the main force of the sunflower protein-phenolic complex formation was assumed to be hydrophobic attraction. The Stern-Volmer plot indicated that the main quenching mechanism was only static at all temperature conditions.

Phenolic compounds as natural microbial toxin detoxifying agents.

Despite the abundance of promising studies, developments, and improvements about the elimination of microbial toxins from food matrices, they are still considered as one of the major food safety problems due to the lack of their complete avoidance even today. Every year, many crops and foodstuffs have to be discarded due to unconstrained contamination and/or production of microbial toxins. Furthermore, the difficulty for the detection of toxin presence and determination of its level in foods may lead to acute or chronic health problems in many individuals. On the other hand, phenolic compounds might be considered as microbial toxin detoxification agents because of their inhibition effect on the toxin synthesis of microorganisms or exhibiting protective effects against varying damaging mechanisms caused by toxins. In this study, the effect of phenolic compounds on the synthesis of bacterial toxins and mycotoxins is comprehensively reviewed. The potential curing effect of phenolic compounds against toxin-induced damages has also been discussed. Consequently, phenolic compounds are indicated as promising, and considerable natural preservatives against toxin damages and their detoxification potentials are pronounced.

Pressurized pyrolysis of dried distillers grains with solubles and canola seed press cake in a fixed-bed reactor.

Pressurized pyrolysis of biomasses was carried in a fixed bed reactor to obtain gases, bio-oils and chars at elevated temperatures. The products were characterized by GC-MS, FTIR, viscometer, SEM, BET and EDXRFS methods. Experiments were performed at 1, 5 and 10 bar pressure and 400, 500 and 600°C temperatures. The experimental results show that in all the experimental condition the yield of bio-oil from DDGS as higher than that of canola. Yield of non-condensable gases and chars increased, while that of liquid products decreased by pressure. Increasing pressure favoured the formation of low molecular weight gas, such as H2. Maximum surface area of chars was obtained at atmospheric pressure and the surface areas decreased rapidly with increasing pressure. GC/MS results shows that the amount of fatty acids in bio-oils was increased by increasing pressure and bio-oils showed non-Newtonian behavior. Based on EDXRFS results, bio-oils and char contained lots of elements.