Microbiology of day-old chicks: a Philippines street food

Ma. Patricia V. Azanza, Melba P. Ortega

Department of science and nutrition, college of home economics, university of the Philippines, diliman 1101, quezon city, Philippines

Received 29 september 2002: received in revised form 14 march 2003: accepted 17 march 2003

Abstract

The microbiology of Philippines street-vended chicken hatching, candidly terned as day-old chicks, and it sauces was studied. The various cooking stages in the preparation of the street food were considered points for microbial controls in the street vendings of day-old chick. Presence of coagulase positive staphylococci and salmonella spp. In the day-old chick and sauce samples obtained from the various stages of food preparation and vending were established. The microbial profile of fried day-old chick during vending was: <102-104 cfu/g tpc; ≤101 MPN/g coliform count; ≤102 MPN/g coagulase-positive staphylococci and; presense of salmonella spp. Per 25 g sample.

© 2003 Elseiver Ltd. All right reserved.

Keywords: day-old chick; Microbial contamination; poultry

1. Introduction

The Philippine street food terned as day-old chick is chicken hatchling that has been dressed, seasoned, and orange-dyed prior to deep oil friying. Rejects of poultry hatcheries, either as unhatched but mature embryo, newly hatched chicks or seasoned ready to cook day-old chicks, are used as the starting materials for this street food by vendors. Basis for rejection of shell-on mature chick embryo may include abnormalities that are considered to impede hatchability (moreng & avens, 1985). Illnesses, deformities, inferior size and gender are also considerations for rejections of newly hatched chicks.

The emergence of day-old chick s a Philippine street food was reported to be prompted by the need to make use of an abundant supply of male chicken hatchlings (fernandes, 1994). Previously, a significant portion of rejected male chicks was just discarded as waste since these were considered not profitable to rear. Male chicks are said not to fatten as well as female stocks. Also, less male chicks are needed for breeding purpose. Rejected chicks were originally ingenuously converted into a food dish by an enterprising cook from Pampanga, a province in the outskirts of the greater manila area (GMA) that is well known for development of a number of exotic Philippine dishes (Fernandez, 1994). The original dish was then developed as an accompaniment of alcoholic beverages. Since then, fried day-old chick has evolded as a popular street food snack item being peddled in populated areas and centers of trade, both in the rural and urban parts of the country.

The microbial risks associated with the consumption of street vended foods have been widely studied (Aabdussalam & Kaferstein, 1993; Dawson & Canet, 1991; Freese, Romeo-Abal, Solomons, & Gross, 1988; Umoh & Odoba, 1999). In the Philippines, case of local foodborne outbreaks implicating street food in the transmission of foodborne pathogens have long been reported (Diez, 1995; Rocces et al, 2000). The continuing prevalence of street food vending in the country and the accompanying health risks support the sustained interest in the microbial quality of street vended foods. For poultry based food products like the street food day-old chick, the inherent microbial risks like salmonellosis and other foodborne diseases may be expected (Jay et al., 1997; Johnston & Tompkin, 1992). This study was conducted to established the microbial contaminants as ssociated with the preparation and vending of the emerging Philippine street food day-old chick. Results of study could be used by both government food regulatory agencies and the street food vendors themselves in their efforts to ensure the wholesomeness of this emerging street food.

Table 1

Basic steps and specifications for preparation, storage and vending of fried day-old chick

Steps specifications1. Recceipt of raw materials

2. Pre-processing of shell-onEmbryo and newly hatched chicks

3. Pre-cooking of seasoned day-old chick

4. Frying 5. Hold-on display of fried

day-old chick6. Re-frying

Shell-on chicken embryo- Shellstocks bought in corrugated carton or plastic molded trays by the hundreds from

agricultural depots or poultry hatcheries- Shellstocks ready for hatching, most eggs with visible cracks and leaks- Eggs mostly rejects from poultry farms based on defects detected on the developing

embryo Newly hatched live chicks

- Chicks bought contained in plastic crates or chicken wire cages sold by the hundreds- Purchased newly hatched from main agricultural depots or directly from poultry hatcheries- Rejected based on gender, inferior size, deformities and illnesses

Seasoned ready to cook day-old chick- Bought already dressed, seasoned, chilled and ready to cook contained in plastic packaging

materials- Purchased from poultry hatcheries or second party contract food processor

Manual de-shelling of shell-on chicken embryo Slaughtering/bleeding

- Slitting of jugular vein- Subsequent washing with water

Seasoning: orange food color, salt/flavor intensor, pepper, garlic, sugar Cooking options were parboiling and pre-frying

(1) Parboiling in water for 1-2 min, and subsequent refrigerated or iced storage, maximum 8-12 h

(2) Pre-frying in oil, 2 min, and subsequent ambient hold-on, maximum 8-12 h Vegetable oil temperature: 120-165 oC, 2-4 min Optional operation Ambient temperature, maximum of 12 h vending Optional operation Vegetable oil temperature: 120-165 oC, 2-4 min

Reduced aw recorded for seasoned day-old chicks may be attributed to the effect of solutes present in the seasoning mixture that was added to the fresh meat. Pre-cooked day-old chick, both parboiled and pre-fried samples, had a w readings between 0.86and 0.96. pre-frying procedure proved more effective in reducing the aw of seasoned day-old chick samples may be attributed to the desiccation effect of high temperatures attained during cooking. Frying has also been previously shown to cause desiccation in other deep-fried commodities like the street-vended fish balls (Azanza & Gedaria, 1998) and fastfood milkfish rellenado (Azanza, Ortega, & Valdezco, 2001). The fresh and cooked day-old chick samples had pH values in the range of 5.41-6.98 (Table 2). These values are quite proximate to previously reported pH values for poultry product varying from 5.7-6.4 depending on the part (Barnes, mead, &Impey, 1979).

3.3. Microbiological Characteristics

Total plate and coliform counts: the microbial quality profile of day-old chick samples is presented in Table 3. The TPCs and coliform counts for both dressed and seasoned day-old chick samples were 108-109 cfu/g and 104 MPN/g, respectively. These values exceeded the microbial guideline values set for TPC and coliform counts of raw poultry meat which is about 10 5-107 cfu/g and ≤103

MPN/g, respectively (NAS, 1985).

The defeathering procedure for day-old chick was done by scalding in boiled water for 1 min. The method of defeathering facilitied by scalding or semi scalding was reported to be capable of making poultry meat more susceptible to microbial contamination as compared to dry plucked birds (Frazier & Westhoff, 1988). The integument off scalded poultry meat has a greater tendency to be broken, thus making it more susceptible to contamination. Attachment of S. typhimurium to skin of turkey that has been defeathered by scalding was attributed to the possible microbial attachment to collagenous dermal surface with epidermal damage (Kim & Doores, 1993).

The maximum TPCs and coliform counts recorded for pre-cooked day-old chick samples were: (1) parboiled, 10 8 cfu/g and 103

MPN/g and; (2) pre-fried, 106 cfu/g and <100 MPN/g, respectively. Both parboiling and pre-frying procedures were effective in reducing coliform counts to acceptable levels cited for coliform counts of 10 3 MPN/g for ready cooked meals which need further heathing or cooking prior to consumption

Table 2

Pysico-chemical characteristics of street vended fried day-old chick obtained from various stages of production, vending and storagea

Sampling point Temperature (oC) Aw pH1. Chilled and seasoned dressed chick2. Pre-cooked chick

(a) Parboiled methodb Chicks during parboilingCooled parboiled chicks(b) Pre-fried methodd Chicks during fryingCooled pre-fried chicks

3. Completely fried chick4. Re-fried chicks after 5 h hold-on display at ambient conditions

17-19

94-10221-23

84-9231-3686-93

96-101

0.95-0.96

ndc

0.95-0.96

nd0.86-0.940.86-0.93

0.92

5.80-6.51

nd6.76-6.98

nd5.41-6.385.78-6.195.63-6.15

aAnalyses were conducted in three trialsbParboiled method, boiling water (100 oC).cNot determineddPre-fried method, vegetable oil (120-163 oC).

Table 3

Microbiological quality profile of street vended fried day-old chick obtained from various stages of production, storage and vendinga

Food sample TPC (log cfu/g) Coliform (log MPN/g)

Coagulase positive staphylococci (log MPN/g)

Salmonella spp.(± per 25 g)b

1. dressed day-old chick2. chilled seasoned day-old chick3. pre-cooked day-old chick Chilled parboiled day-old chick Pre-fried day-old chick4. fried day-old chick 0 h vending 5 h vending5. spiced vinegar sauces (0 h) 0 h vendng 5 h vending

9.35.3-84

8.0-8.2<2.0-6.2

<2.0-3.9<2.0

<2.0-4.43.1-4.4

4.4<0.5-4.4

3.4-3.7<0.5

<0.5-1.4<0.5

<0.5<0.5

<0.5<0.5-3.4

3.4<0.5

<0.5-2.0<0.5-1.4

1.0-3.01.0-3.4

++

++

++

++

aAnalyses were done in three trials, representing three discrete days of vending operations.b±, positive or negative for salmonella spp. Per 25 g sample.

(NAS, 1985). However, only pre-frying was effective in decreasing TPC levels within the cited guideline value range for pre-cooked meals of about 105-106 cfu/g (NAS, 1985). This is quite expected since the high internal temperatures between 84 and 92 oC for 2-4 min was maintained during the pre-frying process. On the other hand, although final internal temperatures as high as 94-102 oC was recorded for day-old chick samples during parboiling, the actual heating time was only maintained for 1-2 min.

The final frying process was able to reduce further the microbial contamination of the pre-cooked day-old chick by at least 2-4 log units, and 2 log units for TPC and coliform counts, respectively. The completely fried and re-fried day-old chick samples were found to have maximum total plate and coliform counts of 104 cfu/g and 101 MPN/g, respectively. These counts were within the reported guideline values for TPC and coliform count for ready to eat meals of 10 4 cfu/g and 101 MPN/g (NAS, 1985). The efficacy of the frying process to effectively reduce microbial countsof the fried samples may be attributed to the adequate heating applied to the pre-cooked foods. The internal temperatures of the newly fried day-old chick samples were recorded to be between 86 and 101 oC.

Coagulase-positive staphylococci count: dressed day-old chick samples had coagulase-positive staphylococci count <100

MPN/g which is the acceptable limit for staphylococci count for raw poultry meat of (NAS, 1985) (Table 3). With seasoning, however, maximum staphylococci count increased up to about 3 log units. Possible sources of staphylococci contamination were