Grinding characteristics of Asian originated peanuts (Arachishypogaea L.) and specific energy consumption during ultra-high speed grinding for natural peanut butter production

Roasted peanuts of China and India origin were ground in a commercial ultra-high speed grinder operated at 20,000 rpm for 2.0–5.0 min for natural peanut butter production. Grinding characteristics of both peanuts were evaluated in terms of specific energy consumption, Esc with respect to its grinding time and mean particle size. The Esc increased with grinding time with China peanuts having higher Esc than India peanuts. The specific energy consumption modeled to the size reduction ratio of China and India peanuts was predicted more accurately using a linear and exponential model respectively compared to the classical models by Bond, Rittinger and Kick. From the comparison of Bond’s working index, Wi, the ultra-high speed grinder is said to be more energy efficient than other comminutors in terms of its capability to produce finer particle size in shorter time than the rest

Quality changes of stabilizer-free natural peanut butter during storage

The storage stability of preservative-free peanut butter was evaluated for changes in physicochemical quality including moisture content and water activity, microbiological properties, oxidative stability and textural quality in terms of spreadability and firmness. The study was conducted for 16 weeks at storage temperature of 10, 25 and 35 °C on natural and pure peanut butter produced from two varieties of peanuts, the Virginia and Spanish TMV-2 varieties of China and India origin, respectively. The peanuts were ground using a high speed grinder for 2.5 and 3.0 min to produce peanut butter without addition of other ingredient. The natural peanut butter exhibited stability and had acceptable microbial count during storage. Storage at 10 °C gave similar textural quality with commercial product until week 8 and without appreciable loss in oxidative stability until week 12. At higher storage temperatures of 25 and 35 °C, oxidative stability was shortened to 4 weeks of storage. Among the factors of storage temperature and time, grinding time and peanut variety, storage temperature had the most significant effects on quality changes of natural peanut butter

Particle size distribution of natural peanut butter and its dynamic rheological properties

This study compared the dynamic rheological properties of natural peanut butter with commercial peanut butter at 25°C. The natural peanut butter was produced using ultra-high speed grinding (˜20,000 rpm) at different grinding times (2–5 min) from peanuts of China and India. Multimodal particle size distribution was observed for all the samples. The linear viscoelastic region obtained from stress sweep test of the peanut butter produced at 2–3 min fell within the linear viscoelastic region of commercial peanut butter of 0.1–11 Pa. Longer grinding time (3.5–5 min) produced a shorter and lower linear viscoelastic region of 0.03–3 Pa. The storage modulus, G′ is an increasing function of particle size distribution. All peanut butter samples exhibited elastic properties