The process protocol for chocolate peanut cream (CPC) was as described by C. A. Chu and A. Resurreccion (2004). Chocolate peanut cream was produced from the Bulgarian “Kalina” peanut cultivar. Raw medium peanut kernels were heated in a roaster (MPK-20I, “Interbis” Ltd. – Bulgaria) at 163°C in 4.5 kg batches for 3–5 min to obtain a medium roast (visual assessment). Peanuts were air-cooled at room temperature; passed through a dry peanut blancher (model EX, Ashton Food Machinery Co. Inc. – USA) twice; hand sorted to inspect and discard foreign material or damaged nuts; then passed through the blancher a third time. Blanched cool peanuts were then passed through a colloid mill (model Type T2, Koruma - Germany) twice to grind the peanuts to a paste. Chocolate syrup (25%), sugar (30%) and stabilizer (Grindsted® PS 105K, Danisco Cultor, USA, Inc) were added to the peanut paste (45%) and passed through a colloid mill. The product was rapidly cooled to 40°C (instant cooling by placing in ice bath), filled into clean jars and stored.

The week before the testing, cocoa powder (Nestle^TM ), nonfat dry milk (Clever^TM ), corn oil (Clever^TM) and powdered sugar (Clever^TM) were purchased from the local supermarket food chain “Billa”. Imitation vanilla flavor and lecithin both were provided by P.I.C.Co, Plovdiv, Bulgaria. The chocolate syrup consisted of cocoa powder (12%), nonfat dry milk (12%), corn oil (38%), powdered sugar (36%), lecithin (1%), and imitation vanilla flavor (1%). The dry ingredients (sugar, nonfat dry milk and cocoa) were blended together in a mixer (Laboratory mixer, Hran-Mash Ltd., Stara Zagora, Bulgaria) on low speed for 2 min. With the mixer maintaining the same speed, vanilla, corn oil, and lecithin were added in that order and mixed for 5 min. The speed was then increased to medium speed for an additional 5 min to obtain a smooth liquid.

The CLT for consumer acceptance was conducted over five consecutive days in commercial booths during an industrial fair in Plovdiv, Bulgaria, in 2005. A total of 152 panelists were recruited and screened for specific criteria as follows.

Untrained consumers were randomly selected, screened, and only the qualified consumers were asked to participate in the test being conducted at a fair booth. The screening process ensured that each consumer panelist was qualified to participate in the test by eliminating individuals with known allergies to peanuts, chocolate, sugar or milk. Regional Center for Scientific and Applied Services (RCSAS) employees or retirees, as well as non-Bulgarian citizens were also excluded from the tests. In addition, participating consumers must have consumed chocolate, peanuts, peanuts and chocolate together, commercial chocolate-peanut cream, peanut products or peanut flavored food at least once a month and be at least 18 years old. During recruitment, an effort was made to include an equal number of participants representing gender and age group.

Before evaluating the samples, consumers participating in the chocolate peanut cream test were asked to complete a demographic questionnaire that requested information concerning their age, gender, ethnic group, marital status, educational background, employment, income of the household, and their consumption patterns for chocolate, Nutella type of products and peanuts, peanut products or peanut flavored food eaten along with chocolate.

Consumers were asked to evaluate one sample (15 g) of CPC in a 50 ml plastic cup with lid. Nine-point scales, were used to rate intensities of the spreadability, chocolate, peanut and overall flavors; and texture. Nine-point JAR scales were used to assess spreadability, aroma, chocolate, peanut and overall flavors as well as texture; while a nine-point hedonic scale was used for overall acceptance. All questions were administered by a trained interviewer who asked questions, one at a time, and recorded panelist responses on individual ballots. The sample evaluated was presented to each consumer by interviewers seated in partitioned booths. Each panelist was asked to evaluate the sample then indicate their answer to each specific question by pointing to a category on large nine-point intensity, JAR or hedonic scales. After the sample was tested, the consumer was dismissed. Evaluations were carried out in three adjacent partitioned booths.

Intensity scale categories were as follows: spreadability (1  =  extremely unspreadable, 5  =  neither spreadable nor unspreadable, 9  =  extremely spreadable), chocolate, peanut and overall flavor (1  =  extremely weak, 5  =  neither weak nor strong, 9  =  extremely strong), and texture (1  =  extremely smooth, 5  =  neither crunchy nor smooth, 9  =  extremely crunchy). The Just-about-right (JAR) scale categories were as follows: spreadability (1  =  very much less spreadable, 2  =  much less spreadable, 3  =  slightly less spreadable, 4  =  very slightly less spreadable, 5  =  just-about-right, 6  =  very slightly more spreadable, 7  =  slightly more spreadable, 8  =  much more spreadable, 9  =  very much more spreadable). Aroma, chocolate, peanut and overall flavors were rated as follows (1  =  very much weaker, 2  =  much weaker, 3  =  slightly weaker, 4  =  very slightly weaker, 5  =  just-about-right, 6  =  very slightly stronger, 7  =  slightly stronger, 8  =  much stronger, 9  =  very much stronger), and texture (1  =  very much smoother, 2  =  much smoother, 3  =  slightly smoother, 4  =  very slightly smoother, 5  =  just-about-right, 6  =  very slightly crunchier, 7  =  slightly crunchier, 8  =  much crunchier, 9  =  very much crunchier). Hedonic scale categories for overall acceptance were 1  =  dislike extremely, 5  =  neither like nor dislike, and 9  =  like extremely for each attribute evaluated.

Most consumers rated spreadability of the chocolate peanut cream high in intensity (7.7) and also rated the product optimal for spreadability (Fig. 1). Some consumers who rated spreadability high gave it JAR rating of being more spreadable than optimal.

A slightly “slightly weak” (4.8) intensity rating for chocolate flavor was given to the sample. This intensity corresponded to a less than optimal spreadability rating. To increase acceptance of the peanut cream, more chocolate flavor should be perceived (Figure 2).

Intensity ratings for peanut flavor were equivalent to “neither weak nor strong” (5.8). This corresponded to an optimal peanut flavor (Figure 3).

Intensity ratings were equivalent to “neither weak nor strong” for overall flavor (5.4) and corresponded with optimal ratings (Figure 4).

Texture was rated 4.3 or “slightly smooth,” however, a slightly crunchier texture was considered optimal by more consumers than a smoother product. Consumers who rated the product as smoother also rated the product less than optimal in texture (Figure 5).

Aroma of the peanut cream was rated optimal by consumers (data not presented).

Mean consumer ratings for overall acceptance of chocolate peanut cream are shown in Table 3. Overall acceptance of the treatment formulation was rated high (x  =  7.3 or like moderately). The frequencies of hedonic ratings for overall acceptance are also shown in Table 3. Over 50% of consumers rated the peanut cream either like very much or like extremely. The percentage of consumers that rated the overall acceptance of chocolate peanut cream as like moderately or better (x≥7) was 90.0%.

Overall, JAR ratings showed that all attributes were rated just about right by over 50 % of consumers, except for chocolate flavor (42%) indicating the need for increased perception of chocolate flavor intensity.

A central location test involving 152 respondents has indicated that Bulgarian consumers rated overall acceptance of chocolate peanut spread product as “like moderately”. The results demonstrated that Bulgarian consumers preferred a high degree of spreadability and a medium intensity of peanut and overall flavors. A higher intensity of chocolate flavor and texture than rated in the sample was preferred by consumers. Intensity of chocolate flavor and texture of CPC formulation needs to be increased to be perceived as optimal. Aroma was rated as optimal.