Vanillin biotechnology: the perspectives and future

The biotechnological production of fragrances is a recent trend that has expanded rapidly in the last two decades. Vanillin is the second most popular flavoring agent after saffron and is extensively used in various applications, e.g., as a food additive in food and beverages and as a masking agent in various pharmaceutical formulations. It is also considered a valuable product for other applications, such as metal plating and the production of other flavoring agents, herbicides, ripening agents, antifoaming agents, and personal and home-use products (such as in deodorants, air fresheners, and floor-polishing agents). In general, three types of vanillin, namely natural, biotechnological, and chemical/synthetic, are available on the market. However, only natural and nature-identical (biotechnologically produced from ferulic acid only) vanillins are considered as food-grade additives by most food-safety control authorities worldwide. In the present review, we summarize recent trends in fermentation technology for vanillin production and discuss the importance of the choice of raw materials for the economically viable production of vanillin. We also describe the key enzymes used in the biotechnological production of vanillin as well as their underlying genes. Research to advance our understanding of the molecular regulation of different pathways involved in vanillin production from ferulic acid is still ongoing. The enhanced knowledge is expected to offer new opportunities for the application of metabolic engineering to optimize the production of nature-identical vanillin. © 2018 Society of Chemical Industry     

Effects of different vanilla extraction methods on sensory and colour properties of vanilla ice creams during storage

The effects of enzyme assisted vanilla extract (EAVE), traditional vanilla extract made from the same mature vanilla beans and commercial vanilla extract, adjusted to 0.1% vanillin concentration, on the sensory and colour properties of vanilla ice cream were studied. For the production of 1 kg of ice cream, vanilla extracts contributed 5 mg of vanillin but each extract contributed different amounts of non‐vanillin flavour compounds. Flavour and odour parameters of ice creams did not show changes during 3 weeks of storage while colour parameters decreased in ice cream made with EAVE from the first day of manufacture. When EAVE was used, it produced a whiter colour in the ice cream, which was found to be less stable from the second week of storage. This observation was confirmed with the measurement of L and chroma colour parameters.     

Effect of Tissue Disruption by Different Methods Followed by Incubation with Hydrolyzing Enzymes on the Production of Vanillin from Tongan Vanilla Beans

Vanilla is one of the most popular and valuable flavorings worldwide. Natural vanilla is extracted from the cured vanilla pods of Vanilla planifolia. The main aromatic compound in vanilla is vanillin, a phenolic aldehyde, which is produced by enzymatic hydrolysis of glucovanillin during the curing process. Although the amount of glucovanillin in the uncured green bean is present at the level of 10–15%, only an average of about 2% vanillin yield results from the traditional curing process. Therefore, the aim of the experiment was to increase the vanillin yield by obtaining the maximum conversion of glucovanillin. This was obtained by the addition of exogenous cellulase, pectinase, and beta glucosidase enzymes and cellular-damaging techniques on green Tongan vanilla beans to enhance the interaction between glucovanallin substrate and enzymes and successfully achieved vanillin production ranging from 4.25 to 7.00% on a dry weight basis. These techniques may be further refined and translated into industrial curing practices for improvement of natural vanillin yield from vanilla beans.     

Effects of killing conditions of vanilla (Vanilla planifolia,Andrews) pods during the curing process on aroma composition of pod ethanol extract

The effects on the aroma compositions of ethanol extracts obtained by traditional and enzyme‐assisted methods from seven killing conditions used in vanilla pod curing were studied. Two procedures of vanilla pod killing consisted of either freezing pods at ?10 °C for 24 h or immersing pods in 80 °C water for 10 s each of three times with 30 s intervals resulted in the highest vanillin values in terms percentage of dry weight of the bean (2.84 and 2.96), 4‐hydroxybenzaldehyde (0.18 and 0.20), vanillyl alcohol (0.56 and 0.57) and vanillic acid (0.18 and 0.19 respectively) when traditional vanilla ethanol extraction was used. When this extract was aged for 3 months it showed improvement in flavour compounds. Enzyme‐assisted vanilla ethanol extraction showed a higher content of flavour compounds than traditional extract, for example vanillin 4.38% and 2.96% respectively. Only vanillic acid levels were improved after ageing of the enzyme‐assisted extracts.     

Analysis of the inhibition of food spoilage yeasts by vanillin

The antimicrobial potential of vanillin, the major component of vanilla flavour, was examined against the growth of three yeasts associated with food spoilage, Saccharomyces cerevisiae, Zygosaccharomyces bailii and Zygosaccharomyces rouxii. Minimum inhibitory concentration (MIC) values of 21, 20 and 13 mM vanillin were determined for the three yeast strains, respectively. The observed inhibition was found to be biostatic. During fermentation, the bioconversion of sub-MIC levels of vanillin in the culture medium was demonstrated. The major bioconversion product was identified as vanillyl alcohol, however low levels of vanillic acid were also detected. Neither the vanillyl alcohol nor the vanillic acid was found to be antagonistic to yeast cell growth. The results indicate the importance of the aldehyde moiety in the vanillin structure regarding its antimicrobial activity and that the bioconversion of vanillin could be advantageous for the yeasts, but only at levels below MIC. These bioconversion activities, presumably catalysed by non-specific dehydrogenases, were shown to be expressed constitutively. It was observed that increased vanillin concentrations inhibited its own bioconversion suggesting that the activity required intact cells with metabolic capacity.     

Extraction and purification of ferulic acid from flax shives,wheat and corn bran by alkaline hydrolysis and pressurised solvents

Extraction of ferulic acid and vanillin from flax shives, wheat bran and corn bran were carried out using two extraction methods, non-pressurised alkaline hydrolysis (0.5 M NaOH) and pressurised solvents (0.5 M NaOH, water, ethanol and ammonia). There were no differences in the content of products extracted with non-pressurised and pressurised 0.5 M NaOH solution yielding mostly ferulic acid, p-coumaric acid and small amounts of vanillin. Pressurised low-polarity water (PLPW), pressurised aqueous ethanol (PAE) and pressurised aqueous ammonia (PAA) were efficient in the one-step production of vanillin from ferulic acid in flax shives (guaiacyl-rich), wheat bran and corn bran (ferulic acid-rich). Vanillin was produced from the bound-ferulic acid via cleavage of the aliphatic double bond under the pressurised conditions. Higher content of ferulic acid in the corn bran yielded higher amounts of vanillin compared to wheat bran and flax shives. A simple and efficient purification procedure for ferulic acid from the alkaline extracts is presented. This procedure exploits the solubility of ferulic acid at different ethanol concentrations.     

Utilisation of corn (Zea mays) bran and corn fiber in the production of food components

The milling of corn for the production of food constituents results in a number of low‐value co‐products. Two of the major co‐products produced by this operation are corn bran and corn fiber, which currently have low commercial value. This review focuses on current and prospective research surrounding the utilization of corn fiber and corn bran in the production of potentially higher‐value food components. Corn bran and corn fiber contain potentially useful components that may be harvested through physical, chemical or enzymatic means for the production of food ingredients or additives, including corn fiber oil, corn fiber gum, cellulosic fiber gels, xylo‐oligosaccharides and ferulic acid. Components of corn bran and corn fiber may also be converted to food chemicals such as vanillin and xylitol. Commercialization of processes for the isolation or production of food products from corn bran or corn fiber has been met with numerous technical challenges, therefore further research that improves the production of these components from corn bran or corn fiber is needed. Published 2010 by John Wiley & Sons, Ltd.     

GC–MS and GC–olfactometry analysis of aroma compounds in a representative organic aroma extract from cured vanilla (Vanilla planifolia G. Jackson) beans

Volatile compounds from cured vanilla beans were extracted using organic solvents. Sensory analysis showed that the aromatic extract obtained with a pentane/ether (1/1 v/v) solvent mixture provided the extract most representative of vanilla bean flavour. Sixty-five volatiles were identified in a pentane/ether extract by GC–MS analysis. Aromatic acids, aliphatic acids and phenolic compounds were the major volatiles. By GC–O analysis of the pentane/ether extract, 26 odour-active compounds were detected. The compounds guaiacol, 4-methylguaiacol, acetovanillone and vanillyl alcohol, found at much lower concentrations in vanilla beans than vanillin, proved to be as intense as vanillin.     

Guaiacol production from ferulic acid, vanillin and vanillic acid by Alicyclobacillus acidoterrestris

Alicyclobacilli are thermophilic, acidophilic bacteria (TAB) that spoil fruit juice products by producing guaiacol. It is currently believed that guaiacol is formed by Alicyclobacillus in fruit juices as a product of ferulic acid metabolism. The aim of this study was to identify the precursors that can be metabolised by Alicyclobacillus acidoterrestris to produce guaiacol and to evaluate the pathway of guaiacol production. A. acidoterrestris FB2 was incubated at 45°C for 7days in Bacillus acidoterrestris (BAT) broth supplemented with ferulic acid, vanillin or vanillic acid, respectively. The samples were analysed every day to determine the cell concentration, the supplement concentration using high performance liquid chromatography with UV-diode array detection (HPLC-DAD) and the guaiacol concentration, using both the peroxidase enzyme colourimetric assay (PECA) and HPLC-DAD. The cell concentration of A. acidoterrestris FB2 during the 7days in all samples were above the critical cell concentration of 10(5)cfu/mL reportedly required for guaiacol production. The guaiacol produced by A. acidoterrestris FB2 increased with an increase in vanillin or vanillic acid concentration and a metabolic pathway of A. acidoterrestris FB2 directly from vanillin to guaiacol was established. The high concentration of vanillic acid (1000mg/L) resulted in an initial inhibitory effect on the cells, but the cell concentration increased after day 2. Guaiacol production did not occur in the absence of either a precursor or A. acidoterrestris FB2 and guaiacol was not produced by A. acidoterrestris FB2 in the samples supplemented with ferulic acid. The presence of Alicyclobacillus spp. that has the ability to produce guaiacol, as well as the substrates vanillin or vanillic acid is prerequisite for production of guaiacol.     

Improved rapid authentication of vanillin using δ13C and δ2H values

Vanilla still remains one of the most important and widely used flavours in the food industry and is also extensively employed by fragrance and pharmaceutical manufacturing companies. Natural vanilla flavour, extracted from the pods of the tropic orchid vanilla, is considerably more expensive than synthetic vanillin. The disparity of prices between natural vanillin and that derived from other sources has given rise to many cases of fraudulent adulteration, and for more than 30 years, strenuous efforts have been made to authenticate sources of vanillin. Stable isotope analysis is one of the most powerful analytical tools to distinguish between natural vanillin and that originating from other sources. Recently, a rapid and precise method for analysis of both δ¹³C and δ²H values of plant methoxyl groups has been published. Here, we report an application of the method for the control of authenticity of vanillin. Carbon and hydrogen stable isotope values of the vanillin molecule and vanillin methoxyl groups of vanillin samples of different origins including authentic and synthetic samples were measured. The results clearly show that use of this approach provides a rapid and reliable authenticity assessment of vanillin. The technique used for these studies is robust and rapid, involves minimum sample preparation and requires only a small amount of vanillin sample, usually 1 mg for stable carbon and 4 mg for stable hydrogen analysis.     

Ferulic acid: pharmaceutical functions,preparation and applications in foods

Ferulic acid (4‐hydroxy‐3‐methoxycinnamic acid), an effective component of Chinese medicine herbs such as Angelica sinensis, Cimicifuga heracleifolia and Lignsticum chuangxiong, is a ubiquitous phenolic acid in the plant kingdom. It is mainly conjugated with mono‐ and oligosaccharides, polyamines, lipids and polysaccharides and seldom occurs in a free state in plants. Ferulic acid is a phenolic acid of low toxicity; it can be absorbed and easily metabolized in the human body. Ferulic acid has been reported to have many physiological functions, including antioxidant, antimicrobial, anti‐inflammatory, anti‐thrombosis, and anti‐cancer activities. It also protects against coronary disease, lowers cholesterol and increases sperm viability. Because of these properties and its low toxicity, ferulic acid is now widely used in the food and cosmetic industries. It is used as the raw material for the production of vanillin and preservatives, as a cross‐linking agent for the preparation of food gels and edible films, and as an ingredient in sports foods and skin protection agents. Ferulic acid can be prepared by chemical synthesis and through biological transformation. As polysaccharide ferulate is a natural and abundant source of ferulic acid, preparation of ferulic acid from plant cell wall materials will be a prospective pathway. Copyright © 2004 Society of Chemical Industry     

基于感官导向的香荚兰特征风味物质分析及重构

采用顶空固相微萃取结合气相色谱-质谱联用法分析香荚兰提取物挥发性香气成分组成。以感官为导向,利用嗅觉阈值、香气活性值（odour active value,OAV）及香气重组实验研究香荚兰提取物特征风味物质并进行重构。结果表明,香荚兰提取物中共检出83种香气成分,与香荚兰提取物特征风味密切相关的奶香、甜香、酸香、膏香、焦香、豆香和辛香香韵特征成分共有34种。基于OAV判断香兰素、4-(乙氧基甲基)苯酚、愈创木酚、乙酸、4-乙烯基愈创木酚、香草醇乙醚等14种化合物为香荚兰提取物特征风味的关键贡献成分。14种关键贡献成分的重组样品具有香荚兰样的奶香、甜香、烟熏香和酸香,香荚兰特征香气风格辨识度明显,与香荚兰特征风味天然香原料的感官相似度达92.33%。香兰素、4-(乙氧基甲基)苯酚、愈创木酚、乙酸、4-乙烯基愈创木酚、香草醇乙醚、乳酸乙酯等14种化合物被鉴定为香荚兰特征风味物质,可作为香荚兰特征风味天然香原料质控的关键指标,也可为复配重构香荚兰特征风味添加剂提供物质基础。     

饮料酒中香草醛的研究进展

香草醛是饮料酒中一种非常重要的香气化合物,因其具有令人愉悦的甜香及香荚兰豆香草香气,同时具有一定的生理功能而被广泛关注。香草醛具有很强的极性且在酒中含量甚微,常规的检测方法难以有效检出饮料酒中香草醛的含量,探究酒中香草醛的分析方法一直是研究的课题。饮料酒的原辅料细胞壁中含有丰富的木质素、阿魏酸等,是形成香草醛的重要前驱物质,它可以通过真菌、细菌等微生物经非氧化脱羧反应等代谢途径在酿造过程中转换成香草醛。本文从饮料酒中香草醛的分析方法、香气贡献、含量差异及形成机理等方面进行综述,以期为我国饮料酒中香草醛的研究提供理论参考。     

Process engineering for bioflavour production with metabolically active yeasts – a mini‐review

Flavours are biologically active molecules of large commercial interest in the food, cosmetics, detergent and pharmaceutical industries. The production of flavours can take place by either extraction from plant materials, chemical synthesis, biological conversion of precursor molecules or de novo biosynthesis. The latter alternatives are gaining importance through the rapidly growing fields of systems biology and metabolic engineering, giving efficient production hosts for the so‐called 'bioflavours', which are natural flavour and/or fragrance compounds obtained with cell factories or enzymatic systems. Yeasts are potential production hosts for bioflavours. In this mini‐review, we give an overview of bioflavour production in yeasts from the process‐engineering perspective. Two specific examples, production of 2‐phenylethanol and vanillin, are used to illustrate the process challenges and strategies used. Copyright © 2014 John Wiley & Sons, Ltd.     

微生物转化法生产香兰素

实验室保藏的一株链霉菌L1 93 6,能以阿魏酸和香兰素为唯一碳源生长 ,并能将阿魏酸转化为香兰素。研究中发现 ,阿魏酸是生产香兰素的较佳底物 ,添加量可达每升数克。发酵至 1 6h后添加阿魏酸 ,此时链霉菌L1 93 6对阿魏酸的转化能力最强。此株链霉菌不仅能耐受高浓度的香兰素 ,而且具有一种与其他菌株完全不同的代谢流。在转化阿魏酸时 ,当香草酸的积累量达到 2 0 0mg/L时 ,就开始积累香兰素作为代谢的主要过量合成产物。流加 2次底物阿魏酸使之浓度达 1 3g/L ,产物浓度达到 7 1 2g/L。相应的摩尔转化率为 69 9%。     

Utilization of Fish Processing By-Products in the Gelatin Industry

Since the bovine spongiform encephalopathy crisis, there has been a growing interest for finding an alternative source of raw materials for gelatin production. Gelatin produced from fish processing by-products is a potential alternative to mammalian gelatin. Fish processing generates solid wastes that can be as high as 50–80% of the original raw material. These wastes are an excellent raw material for preparation of high protein foods. About 30% of the wastes consists of skin and bone with a high collagen content. Fish gelatin can be obtained by hydrolysis of collagen the principal protein found in skin and bone. Fish skin and bone gelatin can be prepared with bloom strength similar to that obtained from mammalian sources. Fish gelatin has numerous applications, particularly, in the food, pharmaceutical, and photographic industries due to its unique chemical and physical properties. This review presents how fish processing by-products can be utilized in the manufacture of gelatin.     

Bioutilisation of agro‐industrial waste for lactic acid production

With the advancement in science and technology, the importance of bioconversion of industrial waste into value‐added products through biotechnological route has been realised. Moreover, to make the process economic and environment responsive, agro‐industrial waste/by‐products can be used as substrates in fermentation processes as an inexpensive raw material. In the field of food biotechnology, organic acids represent the third largest category among the biological products, which can be produced chemically or by fermentation process. Among organic acids, lactic acid holds an important position because of its multivariate applications in food, pharmaceutical, cosmetics, textiles and other industries. Traditionally, lactic acid was produced from pure substrates, but agricultural feedstocks and industrial by‐products have evoked the interest of researchers to use them as raw materials for the biotechnological production of lactic acid. The utilisation of biomass has gained major attention due to environmental hazards, scarcity of fossil fuels and meet the increasing world food and feed demand. Integrated biorefinery approaches have also been adopted for the production of lactic acid along with primary product to minimise the cost. This review provides comprehensive information on the recent advances in biotechnological production of lactic acid utilising agro‐industrial waste/by‐products.     

Enzyme-Assisted Process for Production of Superior Quality Vanilla Extracts from Green Vanilla Pods Using Tea Leaf Enzymes

Vanilla planifolia Andrews is a perennial tropical vine and is an orchid grown for its pleasant flavor. There is an increasing trend world over for using natural flavors. Vanilla being an important food flavoring ingredient, the demand for natural vanilla extract is increasing. Hence, the aim of the present study was to prepare vanilla extract from green beans without going through the elaborate and time-consuming conventional curing process. Vanilla beans after size reduction were mixed in a suitable proportion with tea leaf enzyme extract (TLEE) and incubated to facilitate action of enzymes on vanilla flavor precursors. The beans mix was squeezed, and the filtrate was treated with ethanol to extract the vanilla flavor. TLEE-treated extracts had higher vanillin content (4.2%) compared to Viscozyme extract (2.4%). Also, it had higher intensity of vanilla flavor, sweet, and floral notes. Further, electronic nose analysis confirmed the discrimination between extracts. It was concluded that the use of TLEE is very much useful to obtain higher yield of vanilla extract and superior quality vanilla flavor, which avoids the traditional laborious and time-consuming curing process.     

乳酸菌对真菌毒素的减毒研究进展

真菌毒素是由多种真菌产生的有毒次生代谢产物，它们对食品和饲料的污染已经给人和动物的健康造成了潜在的危害。乳酸菌作为去除真菌毒素的一种替代策略，在大规模、低成本的食品减毒方面显示出良好的潜力。本文总结了食品中几种主要真菌毒素的特征，从乳酸菌对真菌毒素产生的抑制、体外吸附、体内毒性缓解等方面概述相关国内外研究进展，并关注乳酸菌减毒在食品体系中的应用，以期为乳酸菌在食品和饲料中作为真菌毒素天然清除剂的应用提供理论参考。