In the manufacture of herbal medicinal tablets, dried plant extracts are employed as the therapeutic ingredient. These powders, usually obtained by spray drying, are typically hygroscopic and possess poor flow and compactability for the manufacture of tablets by direct compression (DC). Besides, spray-drying operating conditions and liquid feed composition are reported to be dependent on the herbal medicine. Consequently, the production of dried extracts implies long new product development times. Therefore, the goal of this paper was to: (a) provide recommendations as initial production point of fruit powder suitable for DC by spray drying and (b) study the powder properties to identify those that are affected by the extract nature. Particularly, a unique set of operating conditions was found to be appropriate to produce powders of seven different medicinal plant extracts. In fact, all the spray-dried products showed adequate flowability, stability and compactability.

Powders properties, as particle size and morphology, moisture content, hygroscopicity, flowability and compact hardness were not a function of the type of herb. Conversely, the process yield and glass transition temperature, particle and bulk densities, powder composition, compact porosity, wetting and disintegration times were found to be dependent on the chemical nature of the herbs.

Graphical abstract

A single set of spray-drying operating conditions and a unique liquid feed formulation are proposed to process different aqueous medicinal extracts in order to obtain powders with adequate flowability, stability and compactability.

Fermented plant extract (FPE) is a kind of plant functional food fermented by various microorganisms to make a beverage or other physical forms. To provide technical support for the industrial production of gynostemma extract powder, the quality characteristics of fermented plant extract prepared by hot air-drying, spray drying, vacuum microwave drying, and freeze-drying are compared for an FPE product. The effects of maltodextrin, soluble starch, and β-cyclodextrin as a drying agent on drying effect were studied. Results show that spray-dried FPE powder has the highest bulk density, the smallest average particle size, while the vegetable powder produced by freeze-drying has the best color and flavor, the highest content of key components including total sugar, soluble protein, vitamin C, total polyphenol content, and highest antioxidant capacity.

Nature has always been, and still is, a source of foods and ingredients that are beneficial to human health. Nowadays, plant extracts are increasingly becoming important additives in the food industry due to their antimicrobial and antioxidant activities that delay the development of off-flavors and improve the shelf life and color stability of food products. Due to their natural origin, they are excellent candidates to replace synthetic compounds, which are generally considered to have toxicological and carcinogenic effects. The efficient extraction of these compounds from their natural sources, along with the determination of their activity in the commercialized products, have been great challenges for researchers and food chain contributors to develop products with positive effects on human health. The objective of this Special Issue is to highlight the existing evidence regarding the various potential benefits of the consumption of plant extracts and plant extract-based products, with emphasis on in vivo works and epidemiological studies, the application of plant extracts to improve shelf-life, the nutritional and health-related properties of foods, and the extraction techniques that can be used to obtain bioactive compounds from plant extracts.

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Foods is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2200 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Obesity is a condition involving excessive accumulation of body fat that may impair health. The global prevalence of obesity has risen dramatically, increasing more than 2-fold since 1980. In 2014, over 1.9 billion adults worldwide were overweight, of which more than 600 million were estimated to be obese [1]. Obesity contributes to the development of hypertension, dyslipidemia, type 2 diabetes mellitus, coronary artery disease, and stroke, as well as overall mortality [2]. Obesity also leads to an increase in socioeconomic burden. The total socioeconomic costs of overweight and obesity in Korean adults in 2005 were estimated to be approximately US$1.8 billion, equivalent to 3.7% of the national health care expenditure for that year [3]. Hammond et al. [4] suggested that the total annual economic costs associated with obesity in the United States are in excess of US$ 215 billion. Development and implementation of cost-effective interventions for obesity prevention and management are essential to reduce the huge economic burden of obesity [5].

Treatment of obese patients requires a multifaceted approach, including dietary therapy, regular physical activity, behavioral therapy, and/or pharmacotherapy [6]. Comprehensive lifestyle intervention is foundational to obesity management, and adjunctive pharmacotherapy may be considered for individuals who are unable to achieve or maintain weight loss with comprehensive lifestyle intervention and have a body mass index (BMI) ≥30 kg/m2, or ≥27 kg/m2 with comorbidity [7]. Although the addition of weight loss medications to a lifestyle modification intervention can help obese individuals achieve greater weight loss, their body weight can rebound if they stop taking the medications. Since the withdrawal of sibutramine in 2010 because of the risk of serious cardiovascular adverse events, concerns about the safety of anti-obesity medications have led to a steady decline in prescription and use of these medications [8]. Due to the high costs, serious complications, and limited duration of effectiveness of anti-obesity drugs, there has been growing interest in and use of relatively inexpensive, safe, and effective functional food products from natural sources that are capable of aiding weight loss [9, 10].

Plants are considered good natural sources of bioactive compounds with potential anti-obesity properties [11, 12]. These plant-derived anti-obesity compounds induce weight loss through various mechanisms, including regulating lipid metabolism, suppressing food intake, and stimulating energy expenditure [10, 11]. However, there is still a paucity of data on the efficacy and safety of herbal plant preparations in obesity treatment. In order to provide obese patients with accurate and reliable information about effective and safe natural anti-obesity agents, there is a need for high-quality studies on the efficacy and safety of natural herbal products that claim to exert a weight reducing effect [13, 14]. In Korea, it is possible for a health functional food with body fat reducing effects to be approved for use after review, by the Ministry of Food and Drug Safety, of results of a clinical trial on the efficacy and safety of the product [15].

YY-312 is a acer truncatum bunge extract from Imperata cylindrical Beauvois, Citrus unshiu Markovich, Evodia officinalis Dode [16]. These plants have been commonly used as medicinal herbs in Korea, and have been reported to have health promoting effects, including reduction of body fat. Evodiamine, a major alkaloidal compound extracted from Evodia officinalis Dode, was thought to elicit anti-obesity effects through uncoupling protein-1 (UCP1) thermogenesis, but it was also suggested to have the potential to prevent obesity by inhibiting adipocyte differentiation through stimulating the extracellular signal regulated kinase (ERK)/mitogen activated protein kinase (MAPK) signaling pathway [17]. Citrus unshiu Markovich, the peel of immature citrus fruit in the Rutaceae family, is known to have plenty of flavonoids [18]. Citrus peel extracts have been reported to exert an anti-obesity effect through the promotion of β-oxidation and lipolysis in adipose tissue [19]. Imperata cylindrical Beauvois, the root of cogongrass in the Poaceae family, is known to have potent anti-oxidant activity due to its abundant polyphenols [20].