Vetch is a low-cost legume commonly grown in Pakistan with seeds that resemble lentils. Its primary use is as an animal feed, and it is used as a foodstuff by rural populations mainly at times of food shortage. Yet while vetch has a high protein level, of between 26.5 and 28.7 percent, fat content is only 1.36 percent. Moreover, the protein is said to be of a superior quality to that found in cereals. "The use of vegetable extracts/proteins in developing new dairy products like frozen desserts, cheese, yogurt etc is increasing day by day," wrote the research team from Pakistan's University of Agriculture in Faisalabad and the University of Strathclyde in Galsgow, UK, in the International Journal of Food Science and Technology (early online). Moreover, they noted research linking high intake of full-fat dairy to mortality from coronary heart disease as a factor in driving consumers towards low fat dairy alternatives.
"The growing demand for 'healthy' foods is also stimulating innovations and new product development in the food industry throughout the world," they wrote. Prior to conducting their assays on physicochemical, functional properties of vetch-bovine milk blends, and subsequent sensory evaluations, the researchers had to overcome a significant hurdle - safety. Vetch seeds contain a neurotoxin called beta-N-oxalyl-L-alpha-beta-diaminopropionic acid, which can cause a sudden, irreversible disease called lathrysm that paralysis the lower limbs. To avoid this eventuality, the researchers removed a "substantial amount" of the toxin by steeping the vetch in double quantities of water for eight hours at temperatures of 60 to 70 degrees, changing the water seven times. After draining, the vetch was dried in the sun.
Further preparatory steps were also required. The dried vetch was treated with waster at pH4 at 90 degrees C in order to reduce the beany flavor. It was then dried and milled to a fine flour, and the seed coat was separated out. Finally, the researchers prepared four blend of vetch and skimmed cow's milk powder. Blend one contained 12.5 percent vetch flour and 87.5 percent milk powder; blend two was 25 percent vetch and 75 percent milk; blend three was 37.5 percent vetch and 62.5 percent milk; and blend four was 50 percent vetch and 50 percent milk. Cheese was prepared from these blends using 2.5 percent lactic acid bacterial culture of streptococcus thermophillus and streptococcus bulgaricus and rennet. The researchers then tested the four cheeses for physico-chemical properties, such as moisture, total solids, lactose, ash, fat, titratable acidity and pH. Commercial mozzarella cheese was used as a control.
Sensory evaluations of both the cheese and pizza made using the cheese were carried out at day zero, day seven and day 14. Over this 14-day period, the cheese was stored at four degrees, before being used as a pizza topping. This storage period was seen to considerably improve the stretchability and meltability of the cheese. Overall, the best performing cheese on sensory and functional characteristics was seen to be that containing 12.5 per cent vetch. This, the team concluded, could be used for a pizza topping with "desirable characteristics".
"Such a dairy-like product would provide an alternative to consumers seeking foods with low animal fat and lactose." Source: International Journal of Food Science and Technology (early online) DOI: 10.111/j.1365-2621.2006.01512.x Title: Pizza cheese made from vetch-bovine milk
Authors: Salim-ur-Rehman et al.