Effects of heat, processing time and pH on the microflora, aflatoxin content and storability of “wara”, a soft, white cheese

Abstract

SummaryEmploying crude coagulants from sodom apple Calotropis procera, processing conditions of 65 -85 "C for 40-65 min and reduced pH, reductions in microbial population were found in a locallyproduced soft, white cheese "wara". The finished product "wara" did not keep well under ambient conditions (RH 75 5%, temp. 26 _+ 2 "C). From some selected critical control points along the line of processing, Bacillus spp., coliforms, staphylococci and moulds Aspergillus and Mucor spp. were isolated. Aflatoxin B, (AFB,) and aflatoxin M, (AFM,) levels of samples examined ranged from 4.8-5.3 pg/kg and 6.4-7.5 pg/kg, respectively. During production, protein and fat contents of the soft, white cheese showed three-to six-fold and three-to four-fold increases, respectively. ZusammenfassungEinfluB von Temperatur, Bearbeitungszeit und pH-Wert auf Mikroflora, Aflatoxingehalt und Lagerfahigkeit von ,,Wara", einem weichen WeiBkase Bei Anwendung von rohen Koagulantien aus dem ,,sodom apple" Caforropis procera, ProzeDbedingungen von 65 -85 "C fur 40 -65 min und reduziertem pH-Wert wird in dem lokal produzierten weichen Weirjkase ,,Wara" eine verminderte mikrobielle Population festgestellt. Das Endprodukt ,,Wara" ist unter normalen Umgebungsbedingungen (rel. Luftfeuchte 75 5%, Temperatur 26 _+ 2 "C) nicht gut lagerfahig. An einigen ausgewahlten, kritischen Kontrollpunkten wahrend der ProzeDzeit werden Bacillus ssp., Coliforme, Staphylokokken und die Schimmelpilze Aspergillus und Mucor ssp. isoliert. Die Gehalte an Aflatoxin B, (AFB,) und Aflatoxin M, (AFM,) der gepruften Proben liegen im Bereich von 4,8 -$3 pg/kg bzw. 6,4-7,5 pg/kg. Wahrend der Herstellung des weichen WeiBkases erhohen sich die Protein-und Fettgehalte auf 3-bis 6fache bzw. auf 3-bis 4fache Werte.

Production of wara, a West African soft cheese using lemon juice as a coagulant

“…At this point, the populations of total aerobes, Enterobactericeae, psychrotrophs, and mold and yeast decreased to the undetectable level except for the total aerobic counts in the milk inoculated with 10 1 CFU ml À1 of L. monocytogenes which was approximately 1.30 Log 10 CFU ml À1 (Table 1). Adegoke et al (1992) observed a similar decrease in the population of total aerobes at the cooking point during wara manufacture. The inoculated L. monocytogenes was not found at the curdling point (Table 1) and throughout the 5 d storage period at 28 and 15 1C in this study (data not shown).…”

“…Other researchers have isolated Penicillium and Aspergillus spp. from wara in earlier studies (Adegoke et al, 1992). The results of this study suggest that without efficient preservation, the recommended holding time of wara cheese should be significantly shortened.…”

“…The pH of 1-d-old wara cheese manufactured by the leaf extract of C. procera was approximately 5.70-6.90 (Adegoke et al, 1992) and 6.15-6.43 (Adetunji, Alonge, & Chen, Unpublished), whereas the wara cheese manufactured with lemon juice in this study had a pH range of 5.53-5.68 (Table 2). Although the pH of the wara cheese fluctuated throughout the 5 d storage period, storage temperature and storage time did not seem to have a significant influence on the pH of wara ( Table 2).…”

“…Wara has an average shelf life of 2-3 d when stored in whey at ambient temperature (approximately 28 1C) (Adegoke, Nse, & Akanni 1992;Belewu, Belewu, & Nkwunonwo, 2005;Umoh & Solomon, 2001) or 4-5 d when placed in cool well water (approximately 15 1C). The cheese is usually deep fried in vegetable oil near the end of its shelf life in order to further preserve the cheese.…”

Potentials of Coconut Milk as a Substitute for Cow Milk in Cheese Making

“…[5]. In many parts of tropical Africa, milk and milk products are scarce and unaffordable by the majority of the populace [6]. The high and unaffordable cost of milk in some developing countries like Nigeria has made it necessary to source less expensive plant products that could be used as substitutes for milk products or to augment the use of milk products for effectiveness in fighting protein malnutrition.…”