AbstractThis study describes a new method to produce clarified sweet sorghum juice using filter-aid and vacuum filteration system. The juice is clarified and processed into syrup. The syrup is innovatively used as a sugar replacement or ingredient in developing value-added food products, developed as per the Indian food regulations. Evaluation of these food products showed that the samples were acceptable to the consumers and rated at par with commercially available samples. These products are ready for commercialization.

Introduction X Sweet Sorghum [Sorghum bicolor (L.) Moench] belongs to kingdom Plantae, family Poaceae and genus

Sorghum. Sweet sorghum is a smart crop as it has multiple uses.

X Sweet sorghum juice, obtained from low water consuming, short duration and seed-propagated sweet sorghum plant, is a suitable source of syrup.

X Sweet sorghum syrup can be used in the preparation of food products.

X The syrup is thus a natural source for effective sugar replacement in bakery items, energy bars, breakfast cereals, sugar confectionery, fruit and vegetable- based products and beverages.

X Cultivation of sweet sorghum and further value addition offers farmers an excellent opportunity to improve farm income and productivity in the semi-arid-tropics.

X A study was undertaken to explore and demonstrate the innovative usage of sweet sorghum juice in the food industry, which focused both on improving the processing of juice to food-grade syrup and the development of value-added sweet sorghum syrup-based food products.

Processing

Extraction of sweet sorghum juice X Sweet sorghum variety ICSV 25274, grown in postrainy season during the year 2009 at

ICRISAT farm was harvested at physiological maturity.

X Juice was extracted from its stalks using a horizontal three roller crusher (Jagadish No. 6, Gujarat, India).

X The collected juice was pre-heated for about 20 minutes to 70°C, then cooled down to 40°C.

X The juice was clarified using vacuum filtration – A filter cloth was cut to size and placed on the the Buchner funnel.

X A uniform bed of Celite® was prepared on the filter cloth,

X The juice was then poured on the Celite® bed and filtered under vacuum. This process resulted in clarified sweet sorghum juice.

X The juice was concentrated to syrup by heating and slow evaporation. This was carried out under uniform heating conditions with continuous stirring.

X As concentration proceeded, the boiling point increases. Hence it is important to heat under a low flame to avoid charring.

X Scum formed was continuously removed.

X Heating was stopped when the concentrated juice (syrup) was 72° to 76° Brix (Fig. 1).

Innovative Use of Sweet Sorghum Juice in the Food Industry

Saikat Datta Mazumdara*, A Poshadria, Ch Ravinder Reddyb, P Srinivasa Raob, and Belum VS Reddyb

aNutriPlus Knowledge Program, Agri-Bussiness and Innovation Platform (AIP), International Crops Research Institute for Semi-Arid Tropics (ICRISAT), India, bResearch Program – Dryland Cereals, International Crops Research Institute for Semi-Arid Tropics (ICRISAT), India.

*Corresponding author: Tel: +919000686852; Fax: +914030713785; E-mail: s.dattamazumdar@cgiar.org

Advantages in product development X The syrup obtained from sweet sorghum juice contains biologically active substances and micro-nutrients.

X It is a rich source of calcium, potassium and iron, and of natural antioxidants (ascorbic acid and other carotenoids).

X It does not easily crystallize into sugar because of its relatively higher content of reducing sugars as compared to cane sugar.

X Product developers can therefore explore the use of sweet sorghum syrup in applications where crystallization is an issue.

X The study proves that Sweet sorghum syrup can be used in the preparation of a number of food products without compromising on their sensory quality.

Sweet sorghum syrup is shelf-stable: X As the syrup contains 70% or more of sugar, it is shelf-stable and does not ferment. The sugars present in syrup

bind most of the available free water thus reducing the water activity (aw), leaving very little water for microbial growth.

X It is also an acidic food (pH<4.6). Thus sweet sorghum syrup with aw between 0.6 to 0.65 and pH 3.75-4.00, is a shelf-stable product without need for preservatives or refrigeration.

Sweet sorghum syrup for the pharmaceutical industry:Sweet sorghum syrup can be used as an ingredient in Neutraceutical formulations, Medicated sweets, Blended powders, Syrups, Elixirs, Tablets, Lozenges and Capsules.

Sweet sorghum syrup based products

Jan 2011

Harvesting the sweet sorghum crop (proper

stage of maturity)

Crushing of sweet sorghum stalks and

primary filtration

Pre- heating of juice (70°C)

Clarification (Vacuum filtration/ Filter press with

filter aid Celite®)

Clear clarified sweet sorghum juice

Concentration to Syrup (75°Brix)

Value-added sweet sorghum syrup based

products

Fig. 1. Steps involved in processing of sweet sorghum juice to syrup for further value-addition.

Conclusion X Efforts are focused on establishment and promotion of small-scale decentralized sweet sorghum crushing and

syrup making enterprises in rural areas.

X The aim is to reduce poverty and improve livelihoods of smallholder farmers. Through this study, NutriPlus Knowledge Program, Agri-Bussiness and Innovation Platform (AIP)@ICRISAT has successfully developed sweet sorghum syrup-based food products with complete or partial replacement of sugar with sweet sorghum syrup.

X NutriPlus shall further conduct workshops and entrepreneur development programs on establishing and managing commercial sweet sorghum syrup enterprises and partner with the public and private sector to promote these products.

Ready-To-Serve (RTS) Sweet sorghum-based

beverage

Sweet sorghum-based waffle syrup

Tamarind- Sweet Sorghum Sauce

Sweet sorghum-based energy bar

Sweet sorghum based granola bar

Sweet sorghum-based tomato sauce

Multi-grain cookies with sweet sorghum syrup

Sweet sorghum-based mixed-fruit jam

Sweet sorghum-based toffee Sweet sorghum crispies

Analysis

Physico-chemical characteristics: X Total soluble solids (°Brix) and pH of juice, syrup and the developed beverages were measured with a digital

pocket refractometer and pH meter, respectively.

X Acidity was calculated by titrating against 0.1 N NaOH and expressed as percentage of citric acid. Water activity (aw) was measured using a water activity meter (Table 1).

Table 1.Sweet Sorghum products º Brix Water activity (aw) PH Acidity

(as % citric acid)

Juice 18.0±0.05 0.99±0.01 5.17±0.02 0.28±0.36

Syrup 73.0±0.07 0.65±0.02 3.75±0.034 2.34± 0.13

Squash 40.0±0.03 0.95±0.02 2.54±0.052 1.2± 0.43

RTS beverage 10.0±0.06 1.0±0.00 4.00±0.01 0.4±0.02

Nutritional analysis: X Crude protein, total ash, ascorbic acid content, reducing sugars and total sugars were determined (Table 2) using

approved AOAC methods

Table 2.

Samples Protein(%)

Ash(%)

Reducing sugars (%)

Total sugars(%)

Ascorbic acid (mg/100g)

Sorghum juice 1.12±0.1 0.92±0.02 2.95±0.02 18.50±0.1 10.8±0.9Sorghum syrup 5.61±0.1 4.17±0.2 18.53±0.6 72.53±0.1 28.06±0.5Squash 1.35±0.06 0.97±0.05 3.33±0.4 41.23 ±0.7 12.12±0.4RTS beverage 0.30±0.02 0.20±0.01 0.90±0.1 9.80±0.7 1.4 ±0.3

Sensory analysis: X The sensory assessments were conducted at the Research and Development laboratory of NutriPlus Knowledge

Program, Agri-Bussiness and Innovation Platform (AIP)@ICRISAT. A panel of 12 persons consisting of staff members and intern students of ICRISAT evaluated the products.