Technology for Wine and Beer Production from Ipomoea batatas

Sandeep Kumar Panda

• Publisher: CRC Press
• Year: 2019
• ISBN:
  9780429614781
• Edition: 1
• Topic: Art
• Subtopic: Culinary Arts

Purple sweet potato (PSP) is a special type of sweet potato with high concentration of anthocyanin pigment in the root. It is rich in starch, sugar, minerals, vitamins and antioxidants like phenolics, ? -carotene, and has a strong prospect as substrate for alcoholic fermentation. The low cost of sweet potato and its prospective usage in the production of alcoholic beverages make it viable for commercialization.

The book reviews the use of the roots of PSP for the production of three novel products, i.e. anthocyanin rich wine (red wine), herbal/medicinal sweet potato wine, and anthocyanin rich beer which have higher health benefit than other wines and beers. The book elucidates the use of novel technologies in the preparation of this non-conventional wine and beer, processing, biochemical and organoleptic quality of the finished products and health implications. It will be of interest to innovators, researchers and students. The novel technologies in wine and beer making described in the book will set a precedence for production of other alcoholic beverages from starchy sources.

1

Introduction

Sweet potato (Ipomoea batatas L.; Family: Convolvulaceae) ranks as the seventh most important food crop of the world (Ray and Ward 2006). Annual sweet potato production worldwide varied from 101.81 million metric tons to 112.84 million metric tons during the year 2012 to 2017 (FAO 2017). China leads in sweet potato production, followed by Malawi and India ranks 10th in the global sweet potato production (http://www.fao.org/faostat/en/#rankings/countries_by_commodity). China alone contributes around 64% of the global sweet potato production during 2017 (Fig. 1.1).

Forty out of the eighty two (82) developing countries of Africa, Asia and Latin America, where sweet potato is grown, considers it as one of the first five most significant food crops produced yearly (Ray and Balagopalan 1997). India is regarded as one amongst the prime producers of sweet potato in the globe with generation of 1.46 million tons of roots during 2017. Sweet potato is generally planted in poorly fertile, marginal lands with inadequate water availability; still it is observed to produce more calories per area per day as compared to other food crops (Horton et al. 1989). Roots of sweet potato enlarge to produce tuberous roots (storage roots) whereas some roots cannot become storage roots and they remain as pencil roots and absorb water and nutrients from the soil. The tuberous roots are the edible part of the sweet potato plant. Henceforth, sweet potato ‘storage roots’ would be mentioned as ‘roots’ instead of tuber (Nedunchezhiyan and Ray 2010) in this book. The fleshy storage roots (Fig. 1.2) are rich in starch content (DW, 50–80% and FW, 7–28%) and the sugar content varies from 4 to 15% on dry weight basis (Li et al. 1994). The roots are also enriched with vitamin C, pro-vitamin A, vitamin B and iron (Ray and Tomlins 2010). Presence of colourful pigments in the storage roots are the characteristic features of some special varieties of sweet potato. Mostly β-carotene and anthocyanin are found to impart colour in these special cultivars (Fig. 1.3) (Woolfe 1992; Ray and Tomlins 2010).

Figure 1.1. Sweet potato production country wise.

Figure 1.2. Sweet potato storage roots.

Alcoholic fermentation for wine, beer and other alcoholic beverages is generally carried out by the application of yeast. During the fermentation, glucose is converted into ethanol and carbon dioxide. The entire reaction occurring in the yeast cell is very intricate and the general reaction is presented as:

${\text{C}}_{\text{6}}{\text{H}}_{\text{12}}{\text{O}}_{\text{6}}{\text{====> 2(CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{OH) + 2(CO}}_{\text{2}})+\text{Energy}\text{(which}\text{is}\text{stored}\text{in}\text{ATP)}$

The chemical representation shows that one mole of glucose translates to two moles of ethyl alcohol and carbon dioxide each, though actually the process is more complex than it appears. Apart from ethyl alcohol and carbon dioxide as principal products, the glucose is biochemically transformed to several byproducts like dead yeast cell mass, glycerol and organic acids like pyruvic acid, ketoglutaric acid, lactic acid, etc. The body of wine is imparted by glycerol. In order to prepare fuller bodied wine and beer, fermentation specialists in wineries and breweries optimize certain physiochemical conditions to generate higher concentration of glycerol as byproduct in the fermentation medium. The sugars used by the yeasts are only the reducing sugars such as glucose, fructose, sucrose and maltose. So the sugars in other complex forms should be first converted to the reducing sugars before allowing fermentation.

Figure 1.3. Anthocyanin rich sweet potato variety

Color version at the end of the book

Natural anthocyanins are known for their protective properties in oxidative stress, microbial infection, non-communicable diseases and many others (Khoo et al. 2017). Several researchers have reported about the high content of anthocyanins with peonidin and cyanidin in purple sweet potatoes. The anthocyanin content differs significantly among various purple sweet potato varieties. A study conducted by Teow et al. (2007) observed a variation in anthocyanin contents (17–531/kg roots) in 19 genotypes. Similarly, another researcher found the anthocyanin content of one cultivar of purple sweet potato to be as high as 1820 mg/kg roots in fresh weight basis (Cevallos-Casals and Cisneros-Zevallos (2003). In a comparative study conducted by Rodriguez-Saona and Wrolstad (2001) it was made out that the anthocyanin content in purple potatoes (Solanum tuberosum L.) ranged between 20 to 400 (mg/kg fw) for thirty three varieties. Similarly, the anthocyanin imparted in coloured fruits and vegetables were found to have anthocyanin content in a range of 20–6000 mg/kg fw (Wrolstad 2000). The health promoting potential of purple sweet potato anthocyanins has been depicted in several studies. Saigusa et al. (2005) have demonstrated about the free radical scavenging property of purple sweet potato anthocyanins. Likewise, attenuation of hepatic dysfunction (Han et al. 2007), enhancement of memory (Wu et al. 2008), fall of high glucose level in blood and insulin resistance (Ray and Tomlins 2010) and anti-proliferative attribute against malignant cells (Wang et al. 2006) were the most important and health promoting features of purple sweet potato anthocyanin. Furthermore, anthocyanin pigments of purple sweet potato are of different types, and the specialty exists with the high content of acylated anthocyanins in comparison with its counterparts. The purple sweet potato anthocyanin has a potential to be used in food and beverage processing as the anthocyanin of purple sweet potato is comparatively stable in high temperature and light (Hayashi et al. 2003; Hayashi et al. 1996). Keeping the above health beneficial attributes of purple sweet potato anthocyanin in mind and further studies on animal models by different researchers have proved it as a potential nutraceutical (Khoo et al. 2017). Lim et al. (2013) demonstrated the protective action of anthocyanin rich sweet potato against colorectal cancer in both in-vitro and in-vivo model as it ceases cell cycle due to anti-proliferative property and apoptosis. Anthocyanin rich sweet potato has been bio-processed to several value added products like curd, lacto-pickle and lacto-juice (Mohapatra et al. 2007; Panda et al. 2009a,b). There are evidences of fermentation of purple sweet potato (rich in anthocyanin) to various alcoholic beverages like wine and beer traditionally in certain areas of Japan and China (Nelson and Elevitch 2011; Odebode et al. 2008). Sweet potato, being rich in starch, vitamins, minerals and anti-oxidants like phenolics, β-carotene and anthocyanin (in some varieties), is highly potential for alcoholic fermentation into wine and beer.

This book deals with:

•  Review of production and application of fermented sweet potato food products, fermented biocommodities and unfermented sweet potato products, especially purple sweet potato, throughout the globe.

•  Alcoholic fermentation of purple sweet potato into anthocyanin rich wine (red wine) by using Saccharomyces cerevisiae as the starter culture.

•  Alcoholic fermentation of purple sweet potato along with medicinal and herbal plant parts into herbal wine using S. cerevisiae as the starter culture.

•  Preparation of beer by using purple sweet potato flakes in different concentrations along with grist (ground malt prepared from barley grains) and hops.

•  Biochemical, multivariate statistical and consumer sensory evaluation of purple sweet potato fermented products in the laboratory.

•  Technoeconomical feasibility study of anthocyanin rich wine and anthocyanin rich beer developed from purple sweet potato.

2

Review of Sweet Potato and Its Fermented Products

2.1 Root and Tuber Crops in Food Perspective

Roots and tuber crops include cassava (Manihot esculenta C.), sweet potato (Ipomoea batatas L.), elephant foot yam (Amorphophallus paeoniifolius), potato (Solanum tuberosum), aroids and other minor root crops such as African yam bean (Sphenostylis stenocarpa) and East Indian arrowroot (Tacca leontopetaloides). Such crops are reported to serve as an important part of the diet of 2.2 billion people throughout the globe (https://www.nri.org/development-programmes/root-and-tuber-crops-in-development/overview). Root and tuber crops are the cheapest source of dietary energy in terms of carbohydrates in developed countries. Most tuber crops are rich in starch (Moorthy 2004), for example the starch content of sweet potato varies from 12–30% depending upon the variety and the environmental and cultivation methods. Potatoes and yam contain a high amount of protein among other root crops. However, methionine and cystine limit amino acids in tuber crop protein. Several researchers have depicted the nutritional and health beneficial properties of root and tuber crops for example as antioxidative, hypoglycemic, hypocholesterolemic, antimicrobial and immunodialatory activities (Chandrasekara and Kumar 2016). Further, the aforesaid health beneficial potentials of tuber crops may be attributed to several bioactive molecules present in root crops, such as phenolics, saponins and phytic acid. Cassava, sweet potato and yam contain ascorbic acid and some varieties of sweet potato are rich in pigments such as β-carotene and anthocyanin, which impart colour as well as a functional property to the root crop. Innumerable recipes using tuber crops are formulated across the globe. These formulations maybe carried out through cooking or fermentation and are associated with the culture and traditions of a particular region. The popular fermented food products prepared from cassava are gari, fufu, lafun, etc. (Panda and Ray 2016). Similarly shochu is a traditional alcoholic beverage of Japan prepared from sweet potato, described in the Section 2.4.4. Other fermented foods from sweet potato include lactic acid fermented juice, cubes and yoghurt. Acidophilus milk and vinegar are also successfully prepared by using sweet potato as substrate (please see Section 2.4.2.1.4 and Section 2.4.2.2.1).

2.1.1 Sweet potato

Sweet potato is a tropical tuber crop belonging to the family Convolvulaceae. The sweet potato plant is an herbaceous perennial vine having alternate round, triangular or cordate leaves and mid-sized sympetalous flowers. Sweet potato is the 7th most significant crop cultivated on earth and among the root and tuber crops; it follows cassava (Ray and Ravi 2005). Sweet potato was initially illustrated by Linnaeus as Convolvulus batatas in 1753. But in 1791 Lanmark classified it in the genus of Ipomoea on the criteria of stigma shape and the surface of pollen grains. For t...

Table of contents

• Cover
• Title Page
• Copyright Page
• Preface
• Table of Contents
• List of Abbreviations
• 1. Introduction
• 2. Review of Sweet Potato and Its Fermented Products
• 3. Unfermented Food Products from Sweet Potato
• 4. Review on Analysis of Wine and Beer
• 5. Materials and Methods for the Preparation of Sweet Potato Alcoholic Beverages
• 6. Materials and Methods for Biochemical and Technoeconomical Feasibility (Large Scale) Studies
• 7. Results and Discussion: Biochemical, Sensory, Statistical and Infrared Studies
• 8. Results and Discussion: Technoeconomical and Cost Economics Report for Industrial Scale Production
• 9. Summary and Conclusion
• 10. References
• Index
• Color Plate Section